TC 3-97.61 (FM 3-97.61)

Military Mountaineering

July 2012

Headquarters, Department of the Army
DISTRIBUTION RESTRICTION:
distribution is unlimited.

Approved

for

public

release;

This publication is available at Army Knowledge Online
(https://armypubs.us.army.mil/doctrine/index.html).

*TC 3-97.61 (FM 3-97.61)
Headquarters
Department of the Army
Washington, DC, 26 July 2012

*Training Circular
No. 3-97.61

Military Mountaineering
Contents
Page
PREFACE.............................................................................................................................................. xi
Chapter 1

MOUNTAIN TERRAIN, WEATHER, AND HAZARDS ............................................. 1-1
Section I. MOUNTAIN TERRAIN ............................................................................. 1-1
Definition .................................................................................................................... 1-1
Composition ............................................................................................................... 1-1
Rock and Slope Types .............................................................................................. 1-1
Rock Classifications .................................................................................................. 1-2
Mountain Building ...................................................................................................... 1-4
Route Classification ................................................................................................... 1-5
Cross-Country Movement.......................................................................................... 1-9
Cover and Concealment .......................................................................................... 1-10
Observation ............................................................................................................. 1-10
Fields of Fire ............................................................................................................ 1-10
Section II. MOUNTAIN WEATHER ........................................................................ 1-10
Considerations for Planning .................................................................................... 1-11
Mountain Air ............................................................................................................ 1-11
Weather Characteristics .......................................................................................... 1-11
Wind......................................................................................................................... 1-12
Humidity ................................................................................................................... 1-13
Cloud Formation ...................................................................................................... 1-14
Types of Clouds....................................................................................................... 1-14
Fronts....................................................................................................................... 1-19
Temperature ............................................................................................................ 1-20
Weather Forecasting ............................................................................................... 1-21
Recording Data ........................................................................................................ 1-21
Section III. MOUNTAIN HAZARDS ....................................................................... 1-23
Subjective Hazards.................................................................................................. 1-23
Objective Hazards ................................................................................................... 1-24
Weather Hazards..................................................................................................... 1-25
Avalanche Hazards ................................................................................................. 1-25

Chapter 2

MOUNTAIN LIVING .................................................................................................. 2-1
Section I. SURVIVAL ............................................................................................... 2-1
Water Supply ............................................................................................................. 2-1

Distribution Restriction. Approved for public release; distribution is unlimited.
*This manual supersedes FM 3-97.61, dated 26 August 2002.
i

Contents

Nutrition ..................................................................................................................... 2-2
Personal Hygiene and Sanitation .............................................................................. 2-6
Section II. ACCLIMATIZATION AND CONDITIONING ........................................... 2-7
Symptoms and Adjustments ...................................................................................... 2-7
Physical and Psychological Conditioning .................................................................. 2-8
Section III. MEDICAL CONSIDERATIONS ........................................................... 2-10
Illness and Injury ...................................................................................................... 2-10
Treatment and Evacuation ...................................................................................... 2-10
Solar Injuries ............................................................................................................ 2-10
Cold-Weather Injuries .............................................................................................. 2-11
Heat Injuries ............................................................................................................ 2-21
Acute Mountain Sickness ........................................................................................ 2-23
Chronic Mountain Sickness ..................................................................................... 2-23
Understanding High-Altitude Illnesses .................................................................... 2-23
High-Altitude Pulmonary Edema ............................................................................. 2-24
High-Altitude Cerebral Edema ................................................................................. 2-25
Hydration in HAPE and HACE ................................................................................ 2-26
Chapter 3

MOUNTAINEERING EQUIPMENT ........................................................................... 3-1
Section I. EQUIPMENT DESCRIPTION AND MAINTENANCE .............................. 3-1
Footwear .................................................................................................................... 3-1
Clothing...................................................................................................................... 3-2
Climbing Software ..................................................................................................... 3-8
Climbing Hardware .................................................................................................. 3-11
Snow and Ice Climbing Hardware ........................................................................... 3-20
Sustainability Equipment ......................................................................................... 3-24
Section II. EQUIPMENT PACKING ....................................................................... 3-28
Choice of Equipment ............................................................................................... 3-28
Tips on Packing ....................................................................................................... 3-32

Chapter 4

ROPE MANAGEMENT AND KNOTS....................................................................... 4-1
SECTION I. PREPARATION, MAINTENANCE, INSPECTION,
TERMINOLOGY ........................................................................................................ 4-1
Preparation ................................................................................................................ 4-1
Care and Maintenance .............................................................................................. 4-1
Inspection .................................................................................................................. 4-3
Terminology ............................................................................................................... 4-3
Section II. COILING, CARRYING, THROWING ...................................................... 4-5
Coiling and Carrying the Rope .................................................................................. 4-5
Throwing the Rope .................................................................................................... 4-7
SECTION III. KNOTS ................................................................................................ 4-8
Square Knot ............................................................................................................... 4-8
Fisherman’s Knot....................................................................................................... 4-9
Double Fisherman’s Knot .......................................................................................... 4-9
Figure-Eight Bend.................................................................................................... 4-10
Water Knot ............................................................................................................... 4-11
Bowline .................................................................................................................... 4-11
Round Turn and Two Half Hitches .......................................................................... 4-12

ii

TC 3-97.61

26 July 2012

Contents

Figure-Eight Retrace (Rerouted Figure Eight)......................................................... 4-13
Clove Hitch .............................................................................................................. 4-14
Wireman’s Knot ....................................................................................................... 4-15
Directional Figure Eight ........................................................................................... 4-17
Bowline-on-a-Bight (Two-Loop Bowline) ................................................................. 4-18
Two-Loop Figure Eight ............................................................................................ 4-18
Figure-Eight Loop (Figure Eight-On-A-Bight) .......................................................... 4-19
Prusik Knot .............................................................................................................. 4-20
Bachman Knot ......................................................................................................... 4-21
Bowline-on-a-Coil .................................................................................................... 4-22
Three-Loop Bowline ................................................................................................ 4-23
Figure-Eight Slip Knot.............................................................................................. 4-24
Transport Knot (Overhand Slip Knot/Mule Knot) ..................................................... 4-24
Kleimhiest Knot ........................................................................................................ 4-25
Frost Knot ................................................................................................................ 4-26
Girth Hitch ................................................................................................................ 4-27
Munter Hitch ............................................................................................................ 4-28
Rappel Seat ............................................................................................................. 4-28
Guarde Knot ............................................................................................................ 4-30
Chapter 5

ANCHORS................................................................................................................. 5-1
Section I. NATURAL ANCHORS ............................................................................. 5-1
Trees.......................................................................................................................... 5-1
Boulders..................................................................................................................... 5-2
Chockstones .............................................................................................................. 5-2
Rock Projections........................................................................................................ 5-3
Tunnels and Arches................................................................................................... 5-4
Bushes and Shrubs ................................................................................................... 5-4
Slinging Techniques .................................................................................................. 5-4
Section II. ANCHORING WITH THE ROPE............................................................. 5-6
Rope Anchor .............................................................................................................. 5-6
Tensionless Anchor ................................................................................................... 5-6
Section III. ARTIFICIAL ANCHORS ........................................................................ 5-6
Deadman ................................................................................................................... 5-6
Pitons ......................................................................................................................... 5-7
Chocks ....................................................................................................................... 5-9
Spring-Loaded Camming Device ............................................................................ 5-11
Bolts ......................................................................................................................... 5-11
Equalizing Anchors .................................................................................................. 5-12

Chapter 6

CLIMBING ................................................................................................................. 6-1
Section I. CLIMBING FUNDAMENTALS................................................................. 6-1
Route Selection ......................................................................................................... 6-1
Terrain Selection for Training .................................................................................... 6-1
Preparation ................................................................................................................ 6-2
Spotting...................................................................................................................... 6-2
Climbing Technique ................................................................................................... 6-2
Safety Precautions .................................................................................................... 6-7

26 July 2012

TC 3-97.61

iii

Contents

Margin of Safety ........................................................................................................ 6-8
Section II. USE OF HOLDS...................................................................................... 6-8
Climbing with Feet ..................................................................................................... 6-8
Use of Hands ........................................................................................................... 6-11
Combination Techniques ......................................................................................... 6-16
Section III. ROPED CLIMBING .............................................................................. 6-23
Tying into Climbing Rope ........................................................................................ 6-23
Presewn Harnesses ................................................................................................ 6-23
Improvised Harnesses ............................................................................................. 6-24
Section IV. BELAY TECHNIQUES ........................................................................ 6-28
Procedure for Managing the Rope .......................................................................... 6-28
Choosing a Belay Technique .................................................................................. 6-30
Establishing a Belay ................................................................................................ 6-33
Setting Up a Belay ................................................................................................... 6-34
Top-Rope Belay ....................................................................................................... 6-37
Section V. CLIMBING COMMANDS...................................................................... 6-37
Verbal Commands ................................................................................................... 6-37
Rope Tug Commands ............................................................................................. 6-38
Section VI. ROPED CLIMBING METHODS .......................................................... 6-39
Top-Roped Climbing................................................................................................ 6-39
Lead Climbing .......................................................................................................... 6-39
Aid Climbing ............................................................................................................ 6-47
Three-Man Climbing Team ...................................................................................... 6-50
Chapter 7

ROPE INSTALLATIONS........................................................................................... 7-1
Section I. FIXED ROPE ............................................................................................ 7-1
Installation ................................................................................................................. 7-1
Utilization ................................................................................................................... 7-1
Retrieval..................................................................................................................... 7-2
Fixed Rope with Intermediate Anchors ..................................................................... 7-2
Section II. RAPPELLING ......................................................................................... 7-5
Selection of Rappel Point .......................................................................................... 7-5
Installation of Rappel Point ........................................................................................ 7-5
Operation of Rappel Point ......................................................................................... 7-6
Recovery of Rappel Point .......................................................................................... 7-7
Types of Rappels....................................................................................................... 7-8
Section III. ONE-ROPE BRIDGE ........................................................................... 7-14
Site Selection ........................................................................................................... 7-15
Installation Using Transport Tightening System ...................................................... 7-15
Installation Using Z-Pulley Tightening System ........................................................ 7-16
Utilization ................................................................................................................. 7-17
Hauling Line ............................................................................................................. 7-19
Retrieval................................................................................................................... 7-20
Section IV. SUSPENSION TRAVERSE ................................................................. 7-21
Site Selection ........................................................................................................... 7-21
Installation ............................................................................................................... 7-21
Retrieval................................................................................................................... 7-24

iv

TC 3-97.61

26 July 2012

Contents

Section V. VERTICAL HAULING LINE .......................................................... 7-25
Site Selection .................................................................................................... 7-25
Installation ........................................................................................................ 7-25
Retrieval............................................................................................................ 7-27
Section VI. SIMPLE RAISING SYSTEMS ...................................................... 7-27
Z-Pulley System ............................................................................................... 7-27
U-Pulley System ............................................................................................... 7-28
Chapter 8

MOUNTAIN WALKING TECHNIQUES ............................................................. 8-1
Basic Principles .................................................................................................. 8-1
Techniques ......................................................................................................... 8-2
Safety Considerations ........................................................................................ 8-4
Navigation ........................................................................................................... 8-5
Route Planning ................................................................................................... 8-9
Route Selection ................................................................................................ 8-11

Chapter 9

MOUNTAIN STREAM CROSSING .................................................................... 9-1
Reconnaissance ................................................................................................. 9-1
Preparation of Troops and Equipment ............................................................... 9-2
Individual Crossings ........................................................................................... 9-3
Team Crossing ................................................................................................... 9-4
Rope Installations ............................................................................................... 9-5
Safety.................................................................................................................. 9-6
Swimming ........................................................................................................... 9-7

Chapter 10

MOVEMENT OVER SNOW AND ICE ............................................................. 10-1
Movement Over Snow ...................................................................................... 10-1
Movement Over Ice .......................................................................................... 10-2
Use of Ice Ax and Crampons............................................................................ 10-2
Glissading ....................................................................................................... 10-12
Snow and Ice Anchors.................................................................................... 10-13
Roped Climbing on Ice and Snow .................................................................. 10-17
Movement on Glaciers.................................................................................... 10-18
Glacier Bivouac Procedures ........................................................................... 10-30

Chapter 11

MOUNTAIN RESCUE AND EVACUATION .................................................... 11-1
Considerations .................................................................................................. 11-1
Planning Rescue Operations ............................................................................ 11-2
Mass Casualties ............................................................................................... 11-3
Special Training ................................................................................................ 11-3
Preparation for Evacuation ............................................................................... 11-4
Manual Carries ................................................................................................. 11-4
Litters ................................................................................................................ 11-6
Rescue Systems............................................................................................... 11-9
Low-Angle Evacuation ...................................................................................... 11-9
High-Angle Evacuation ................................................................................... 11-11

Appendix A

LEVELS OF MILITARY MOUNTAINEERING ................................................... A-1

Appendix B

MEASUREMENT CONVERSION FACTORS.................................................... B-1

Appendix C

AVALANCHE SEARCH AND RESCUE TECHNIQUES ................................... C-1

26 July 2012

TC 3-97.61

v

Contents

GLOSSARY........................................................................................................................... Glossary-1
REFERENCES .................................................................................................................. References-1
INDEX .......................................................................................................................................... Index-1

Figures
Figure 1-1. Cumulus clouds.................................................................................................. 1-15
Figure 1-2. Stratus clouds. ................................................................................................... 1-15
Figure 1-3. Nimbostratus clouds. ......................................................................................... 1-15
Figure 1-4. Stratocumulus clouds. ........................................................................................ 1-15
Figure 1-5. Altocumulus........................................................................................................ 1-16
Figure 1-6. Altostratus. ......................................................................................................... 1-16
Figure 1-7. Cirrus. ................................................................................................................. 1-17
Figure 1-8. Cirrostratus......................................................................................................... 1-17
Figure 1-9. Cumulonimbus. .................................................................................................. 1-17
Figure 1-10. Lenticular.......................................................................................................... 1-17
Figure 1-11. Contrails. .......................................................................................................... 1-19
Figure 2-1. Wind chill chart. .................................................................................................. 2-12
Figure 2-2. Superficial frostbite............................................................................................. 2-20
Figure 2-3. Deep frostbite. .................................................................................................... 2-20
Figure 3-1. Climbing shoes and plastic mountaineering boots. ............................................. 3-2
Figure 3-2. Extreme cold weather clothing system. ............................................................... 3-4
Figure 3-3. Three types of gaiters. ......................................................................................... 3-5
Figure 3-4. Hand wear. ........................................................................................................... 3-6
Figure 3-5. Neck gaiter and balaclava.................................................................................... 3-6
Figure 3-6. Helmets. ............................................................................................................... 3-7
Figure 3-7. Glacier glasses and goggles. ............................................................................... 3-7
Figure 3-8. Kernmantle construction. ..................................................................................... 3-8
Figure 3-9. Tied or sewn runners. .......................................................................................... 3-9
Figure 3-10. Seat harness, field-expedient harness, and full body harness. ....................... 3-10
Figure 3-11. Nonlocking and locking carabiners. ................................................................. 3-11
Figure 3-12. Major and minor axes and three-way loading. ................................................. 3-11
Figure 3-13. Various pitons. ................................................................................................. 3-13
Figure 3-14. Piton hammer. .................................................................................................. 3-13
Figure 3-15. Chocks. ............................................................................................................ 3-14
Figure 3-16. Three-point camming device............................................................................ 3-15
Figure 3-17. Spring-loaded camming devices. ..................................................................... 3-16
Figure 3-18. Chock picks. ..................................................................................................... 3-17
Figure 3-19. Bolts and hangers. ........................................................................................... 3-18
Figure 3-20. Slot, tuber, mechanical camming device. ........................................................ 3-18
Figure 3-21. Figure-eights. ................................................................................................... 3-19
Figure 3-22. Ascenders. ....................................................................................................... 3-19

vi

TC 3-97.61

26 July 2012

Contents

Figure 3-23. Pulley. .............................................................................................................. 3-20
Figure 3-24. Ice ax and ice hammers. .................................................................................. 3-21
Figure 3-25. Crampons......................................................................................................... 3-22
Figure 3-26. Ice screws. ....................................................................................................... 3-23
Figure 3-27. Ice piton............................................................................................................ 3-23
Figure 3-28. Snow anchors, flukes, and pickets................................................................... 3-24
Figure 3-29. Avalanche rescue equipment........................................................................... 3-26
Figure 3-30. Collapsible ski poles. ....................................................................................... 3-28
Figure 4-1. Example completed DA Form 5752-R. ................................................................ 4-2
Figure 4-2. Examples of roping terminology. .......................................................................... 4-4
Figure 4-3. Mountain coil. ....................................................................................................... 4-5
Figure 4-5. Butterfly coil tie-off................................................................................................ 4-6
Figure 4-4. Butterfly coil.......................................................................................................... 4-6
Figure 4-6. Square knot. ......................................................................................................... 4-8
Figure 4-7. Fisherman’s knot. ................................................................................................. 4-9
Figure 4-8. Double fisherman’s knot. ..................................................................................... 4-9
Figure 4-9. Figure-eight bend. .............................................................................................. 4-10
Figure 4-10. Water knot. ....................................................................................................... 4-11
Figure 4-11. Bowline knot. .................................................................................................... 4-12
Figure 4-12. Round turn and two half hitches. ..................................................................... 4-13
Figure 4-13. Figure-eight retrace. ......................................................................................... 4-14
Figure 4-14. Clove hitch. ...................................................................................................... 4-15
Figure 4-15. Wireman’s knot. ............................................................................................... 4-16
Figure 4-16. Directional figure eight. .................................................................................... 4-17
Figure 4-17. Bowline-on-a-bight. .......................................................................................... 4-18
Figure 4-18. Two-loop figure eight. ...................................................................................... 4-19
Figure 4-19. Figure-eight loop. ............................................................................................. 4-19
Figure 4-20. Middle-of-the-rope Prusik knot. ........................................................................ 4-20
Figure 4-21. End-of-the-rope Prusik knot. ............................................................................ 4-21
Figure 4-22. Bachman knot. ................................................................................................. 4-21
Figure 4-23. Bowline-on-a-coil.............................................................................................. 4-22
Figure 4-24. Three-loop bowline. ......................................................................................... 4-23
Figure 4-25. Figure-eight slip knot. ....................................................................................... 4-24
Figure 4-26. Transport knot. ................................................................................................. 4-25
Figure 4-27. Kleimhiest knot. ................................................................................................ 4-26
Figure 4-28. Frost knot. ........................................................................................................ 4-27
Figure 4-29. Girth hitch. ........................................................................................................ 4-27
Figure 4-30. Munter hitch. .................................................................................................... 4-28
Figure 4-31. Rappel seat. ..................................................................................................... 4-29
Figure 4-32. Guarde knot. .................................................................................................... 4-30
Figure 5-1. Trees used as anchors. ....................................................................................... 5-1
Figure 5-2. Boulders used as anchors. .................................................................................. 5-2

26 July 2012

TC 3-97.61

vii

Contents

Figure 5-3. Chockstones. ....................................................................................................... 5-3
Figure 5-4. Rock projections................................................................................................... 5-3
Figure 5-5. Bushes and shrubs. ............................................................................................. 5-4
Figure 5-6. Correctly opposed carabiners. ............................................................................. 5-5
Figure 5-7. Drape. .................................................................................................................. 5-5
Figure 5-8. Wrap. .................................................................................................................... 5-5
Figure 5-9. Girth. .................................................................................................................... 5-5
Figure 5-10. Rope tied to anchor with anchor knot. ............................................................... 5-6
Figure 5-11. Tensionless anchor. ........................................................................................... 5-6
Figure 5-12. Examples of piton placements. .......................................................................... 5-8
Figure 5-13. Hero-loop. .......................................................................................................... 5-8
Figure 5-14. Piton removal. .................................................................................................... 5-9
Figure 5-15. Chock placements............................................................................................ 5-10
Figure 5-16. SLCD placements. ........................................................................................... 5-11
Figure 5-17. Bolt with expanding sleeve. ............................................................................. 5-11
Figure 5-18. Self-equalizing anchors.................................................................................... 5-12
Figure 5-19. Pre-equalized anchor. ...................................................................................... 5-12
Figure 5-20. Effects of angles on an anchor. ....................................................................... 5-13
Figure 6-1. Correct climbing stance—balanced over both feet. ............................................. 6-3
Figure 6-2. Incorrect stance—stretched out. .......................................................................... 6-3
Figure 6-3. Typical climbing sequence. .................................................................................. 6-5
Figure 6-4. Maximum and minimum sole contact................................................................... 6-9
Figure 6-5. Edging technique. .............................................................................................. 6-10
Figure 6-6. Smearing technique. .......................................................................................... 6-10
Figure 6-7. Examples of jamming. ........................................................................................ 6-11
Figure 6-8. Examples of push holds. .................................................................................... 6-12
Figure 6-9. Examples of pull holds. ...................................................................................... 6-13
Figure 6-10. Examples of pinch holds. ................................................................................. 6-14
Figure 6-11. Examples of jam holds. .................................................................................... 6-15
Figure 6-12. Mantling sequence. .......................................................................................... 6-17
Figure 6-13. Undercling. ....................................................................................................... 6-18
Figure 6-14. Lieback on a face. ............................................................................................ 6-18
Figure 6-15. Stemming on a face. ........................................................................................ 6-19
Figure 6-16. Chimney sequence. ......................................................................................... 6-20
Figure 6-17. Slab technique. ................................................................................................ 6-21
Figure 6-18. Descending slab in the crab position. .............................................................. 6-22
Figure 6-19. Tying-in with a bowline-on-a-coil...................................................................... 6-25
Figure 6-20. Improvised seat and chest harness. ................................................................ 6-26
Figure 6-21. Managing the rope. .......................................................................................... 6-29
Figure 6-22. Sitting body belay. ............................................................................................ 6-30
Figure 6-23. Standing body belay. ....................................................................................... 6-31
Figure 6-24. Guide carabiner for rope control in a body belay. ............................................ 6-31

viii

TC 3-97.61

26 July 2012

Contents

Figure 6-25. Munter hitch. .................................................................................................... 6-32
Figure 6-26. Figure-eight device. ......................................................................................... 6-33
Figure 6-27. Anchoring a belay. ........................................................................................... 6-35
Figure 6-28. Belay setup. ..................................................................................................... 6-36
Figure 6-29. Clipping onto protection. .................................................................................. 6-42
Figure 6-30. Use of slings on protection............................................................................... 6-44
Figure 6-31. Use of slings to extend placement positions.................................................... 6-45
Figure 6-32. Use of sling on a wired stopper........................................................................ 6-45
Figure 7-1. Using a fixed rope. ............................................................................................... 7-1
Figure 7-2. Using a self-belay................................................................................................. 7-2
Figure 7-3. Fixed rope with intermediate anchors. ................................................................. 7-3
Figure 7-4. Hasty rappel. ........................................................................................................ 7-9
Figure 7-5. Body rappel. ....................................................................................................... 7-10
Figure 7-6. Seat-hip rappel. .................................................................................................. 7-11
Figure 7-7. Proper hookup using carabiner wrap. ................................................................ 7-12
Figure 7-8. Figure-eight descender. ..................................................................................... 7-13
Figure 7-9. Extended hookup with self-belay. ...................................................................... 7-14
Figure 7-10. Transport tightening system............................................................................. 7-15
Figure 7-11. Transport knot. ................................................................................................. 7-16
Figure 7-12. Round turn around anchor and two half hitches on a bight. ............................ 7-16
Figure 7-13. Tensionless anchor knot. ................................................................................. 7-16
Figure 7-14. Z-pulley tightening system. .............................................................................. 7-17
Figure 7-15. Commando crawl. ............................................................................................ 7-18
Figure 7-16. Monkey crawl. .................................................................................................. 7-18
Figure 7-17. Rappel seat method. ........................................................................................ 7-19
Figure 7-18. Hauling line. ..................................................................................................... 7-20
Figure 7-19. Suspension traverse. ....................................................................................... 7-21
Figure 7-20. A-frame horizontal and vertical wraps.............................................................. 7-22
Figure 7-21. A-frame spreader. ............................................................................................ 7-23
Figure 7-22. Anchoring the A-frame to the traverse rope..................................................... 7-23
Figure 7-23. Carrying rope for use on a traverse. ................................................................ 7-24
Figure 7-24. Vertical hauling line. ......................................................................................... 7-25
Figure 7-25. Attaching the anchor rope to the A-frame. ....................................................... 7-26
Figure 7-26. Z-pulley system. ............................................................................................... 7-28
Figure 9-1. Normal locations of shallowest water and safest crossing sites. ......................... 9-1
Figure 9-2. Individual crossing with staff. ............................................................................... 9-4
Figure 9-3. Chain method for stream crossing. ...................................................................... 9-4
Figure 9-4. Stream crossing using a handline. ....................................................................... 9-6
Figure 9-5. Belay rope for crossing using a handline. ............................................................ 9-6
Figure 10-1. Self-belay on snow. .......................................................................................... 10-1
Figure 10-2. Using ice ax in cane position. .......................................................................... 10-3
Figure 10-3. Ice ax in cross-body or port arms position. ...................................................... 10-3

26 July 2012

TC 3-97.61

ix

Contents

Figure 10-4. Ice ax in anchor position. ................................................................................. 10-4
Figure 10-5. Ice ax in the push-hold position. ...................................................................... 10-4
Figure 10-6. Ice ax in dagger position. ................................................................................. 10-5
Figure 10-7. Ice ax in hammer position. ............................................................................... 10-5
Figure 10-8. Correct and incorrect crampon technique. ....................................................... 10-6
Figure 10-9. Front-pointing with crampons........................................................................... 10-7
Figure 10-10. Flat-footing in crab position. ........................................................................... 10-7
Figure 10-11. Use of ice ax in descent. ................................................................................ 10-7
Figure 10-12. Climbing sequence. ....................................................................................... 10-9
Figure 10-13. Step cutting and handhold cutting................................................................ 10-10
Figure 10-14. Self-arrest technique. ................................................................................... 10-11
Figure 10-15. Glissading techniques. ................................................................................. 10-13
Figure 10-16. Ice piton pair................................................................................................. 10-14
Figure 10-17. Placement of ice screw using the pick. ........................................................ 10-14
Figure 10-18. Horseshoe or bollard anchor........................................................................ 10-15
Figure 10-19. Equalized anchor using pickets. .................................................................. 10-16
Figure 10-20. Boot-ax belay. .............................................................................................. 10-17
Figure 10-21. Glacier cross-section. .................................................................................. 10-19
Figure 10-22. Glacier features. ........................................................................................... 10-19
Figure 10-23. Ablation zone of glacier in summer. ............................................................. 10-21
Figure 10-24. Rope teams moving in accumulation zone of a glacier. .............................. 10-21
Figure 10-25. Preparation for roped movement. ................................................................ 10-22
Figure 10-26. Prusik ascending technique. ........................................................................ 10-27
Figure 10-27. Z-pulley hauling system. .............................................................................. 10-29
Figure 11-1. Sling-rope carry. ............................................................................................... 11-5
Figure 11-2. Rescue and recovery system (NSN 6530-01-260-1222). ................................ 11-7
Figure 11-3. Rope litter. ........................................................................................................ 11-8
Figure 11-4. Low-angle evacuation—descending. ............................................................. 11-11
Figure 11-5. Cliff evacuation descent. ................................................................................ 11-12
Figure A-1. Level 1, Basic Mountaineer tasks. .......................................................................A-2
Figure A-2. Level 2, Assault Climber tasks. ...........................................................................A-2
Figure A-3. Level 3, Mountain Leader tasks...........................................................................A-3

Tables
Table 1-1. Comparison of rating systems............................................................................... 1-8
Table 1-2. Avalanche hazard evaluation (GREEN-YELLOW-RED) checklist. ..................... 1-30
Table 2-1. Correlation of rapid ascent rates and AMS symptoms.......................................... 2-7
Table 6-1. Rope commands. ................................................................................................ 6-38
Table 7-1. Rappel commands. ............................................................................................... 7-6
Table 8-1. Time-distance formulas. ...................................................................................... 8-11

x

TC 3-97.61

26 July 2012

Preface
Mountains exist in almost every country in the world and almost every war has included some type of mountain
operations. This pattern will not change; therefore, Soldiers will fight in mountainous terrain in future conflicts.
Although mountain operations have not changed, several advancements in equipment and transportation have
increased the Soldiers’ capabilities. The helicopter now allows access to terrain that was once unreachable, or
that was only reachable by slow, methodical climbing. Inclement weather, however, may place various
restrictions on the capabilities of air assets available to a commander. The unit must then possess the necessary
mountaineering skills to overcome adverse terrain to reach an objective.
This training circular details techniques Soldiers and leaders must know to cope with mountainous terrain.
These techniques are the foundation upon which the mountaineer must build. They must be applied to the
various situations encountered to include river crossings, glaciers, snow-covered mountains, ice climbing, rock
climbing, and urban vertical environments. The degree to which this training is applied must be varied to
conform to known enemy doctrine, tactics, and actions. This TC also discusses basic and advanced techniques
to include acclimatization, illness and injury, equipment, anchors, evacuation, movement on glaciers, and
training.
This training circular is a training aid for use by qualified personnel in conjunction with FM 3-97.6, Mountain
Operations, which is used for planning operations in mountainous terrain. Personnel using TC 3-97.61 should
attend a recognized Department of Defense Mountain Warfare School for proper training. Improper use of
techniques and procedures by untrained personnel may result in serious injury or death. Personnel should
be certified as Level I, Basic Mountaineer; Level II, Assault Climber; or Level III, Mountain Leader before
using TC 3-97.61 for training (see Appendix A).
The measurements in this publication are stated as they are used in training (either metric or standard).
Appendix B contains a measurement conversion chart for your convenience.
This book applies to the Active Army, the Army National Guard (ARNG)/Army National Guard of the United
States (ARNGUS), and the United States Army Reserve (USAR) unless otherwise stated.
The proponent for this publication is the United States Army Training and Doctrine Command (TRADOC).
The preparing agency is the U.S. Army Maneuver Center of Excellence (MCoE). Send comments and
recommendations by any means, U.S. mail, e-mail, fax, or telephone, using the format of DA Form 2028,
Recommended Changes to Publications and Blank Forms. Point of contact information is as follows.
E-mail:
[email protected]
Phone:
706-544-6448 (DSN 834)
Fax:
706-544-6421 (DSN 834)
U.S. Mail: Commander, Ranger Training Brigade
ATTN: ATSH-RB / Edmunds
10850 Schneider Rd, Bldg 5024
Ft Benning, GA 31905
Unless otherwise stated, whenever the masculine gender is used, both men and women are included.

26 July 2012

TC 3-97.61

xi

This page intentionally left blank.

Chapter 1

Mountain Terrain, Weather, and Hazards
Commanders must consider the effects terrain and weather will have on their
operations, mainly on their troops and logistics efforts. Weather and terrain combine
to challenge efforts in moving supplies to forward areas. Spring storms, which may
deposit a foot of snow on dry roads, combined with unprepared vehicles, create
hazardous situations. Helicopters are a valuable asset for use in moving men and
supplies, but commanders should not plan to use them as the only means of
movement and resupply. Alternate methods must be planned due to the variability of
weather. Units scheduled for deployment in mountainous terrain should become
self-sufficient and train under various conditions. Commanders must be familiar with
the restraints that the terrain can place on a unit.

SECTION I. MOUNTAIN TERRAIN
1-1. Operations in the mountains require Soldiers to be physically fit and leaders to be experienced in
operations in this terrain. Problems arise in moving men and transporting loads up and down steep and
varied terrain in order to accomplish the mission. Chances for success in this environment are greater when
a leader has experience operating under the same conditions as his men. Acclimatizing, conditioning, and
training are important factors in successful military mountaineering.

DEFINITION
1-2. Mountains are land forms that rise more than 500 meters above the surrounding plain and are
characterized by steep slopes. Slopes commonly range from 4 to 45 degrees. Cliffs and precipices may be
vertical or overhanging. A mountains may consist of an isolated peak, a ridge(s), a glacier(s), snowfield(s),
compartment(s), or a complex range that extends for long distances and obstructs movement. Mountains
usually favor the defense; however, attacks can succeed by using detailed planning, rehearsals, surprise,
and well-led troops.

COMPOSITION
1-3. All mountains are made up of rocks and all rocks are made up of minerals (compounds that cannot be
broken down except by chemical action). Of about 2,000 known minerals, seven rock-forming minerals
comprise most of the earth’s crust. Quartz and feldspar make up granite and sandstone. Olivene and
pyroxene give basalt its dark color. Amphibole and biotite (mica) are the black crystalline specks in granitic
rocks. Calcite, the only one of the seven that does not contain silicone, is found in limestone.

ROCK AND SLOPE TYPES
1-4. Different types of rock and different slopes present different hazards. The following paragraphs
discuss the characteristics and hazards of the different rocks and slopes.

GRANITE
1-5. Granite produces fewer rockfalls, but its jagged edges make pulling rope and raising equipment more
difficult. Granite is abrasive and increases the danger that ropes or accessory cords will be cut. Climbers
must beware of large loose boulders. After a rain, granite dries quickly. Most climbing holds are found in
cracks. Face climbing can be found, however, it cannot be protected.

26 July 2012

TC 3-97.61

1-1

Chapter 1

CHALK AND LIMESTONE
1-6. Chalk and limestone are slippery when wet. Limestone is usually solid; however, conglomerate type
stones may be loose. Limestone has pockets, face climbing, and cracks.

SLATE AND GNEISS
1-7. Slate and gneiss can be firm and or brittle in the same area (red coloring indicates brittle areas).
Rockfall danger is high, and small rocks may break off when pulled or when pitons are emplaced.

SANDSTONE
1-8. Sandstone is usually soft, causing handholds and footholds to break away under pressure. Chocks
placed in sandstone may or may not hold. Sandstone should be allowed to dry for a couple of days after a
rain before climbing on it―wet sandstone is extremely soft. Most climbs follow a crack. Face climbing is
possible, but any outward pull will break off handholds and footholds, and it is usually difficult to protect.

GRASSY SLOPES
1-9. Penetrating roots and increased frost cracking cause a continuous loosening process. Grassy slopes
are slippery after rain, new snow, and dew. After long, dry spells, clumps of the slope tend to break away.
Weight should be distributed evenly; for example, use flat hand push holds instead of finger pull holds.

FIRM SPRING SNOW (FIRN SNOW)
1-10. Stopping a slide on small, leftover snow patches in late spring can be difficult. Routes should be
planned to avoid these dangers. Self-arrest should be practiced before encountering this situation.
Beginning climbers should be secured with rope when climbing on this type surface. Climbers can glissade
down firn snow if necessary. Firn snow is easier to ascend than walking up scree or talus.

TALUS
1-11. Talus refers to rocks larger than a dinner plate, but smaller than boulders. They can be used as
stepping-stones to ascend or descend a slope. However, if a talus rock slips away it can produce more
injury than scree because of its size.

SCREE
1-12. Scree refers to small rocks from pebble size to dinner plate size. Running down scree is an effective
method of descending in a hurry. A Soldier can run at full stride without worry―the whole scree field is
moving with him. Climbers must beware of larger rocks that may be solidly planted under the scree.
Ascending scree is tedious. Scree does not provide a solid platform and will only slide under foot. If
possible, avoid scree when ascending.

ROCK CLASSIFICATIONS
1-13. Rock is classified by origin and mineral composition.

IGNEOUS ROCKS
1-14. Deep within the earth’s crust and mantle, internal heat, friction and radioactive decay creates
magmas (melted silicate minerals) that solidify into igneous rocks upon cooling. When the cooling occurs
at depth, under pressure, and over time, the minerals in the magma crystallize slowly and develop well,
making coarse-grained plutonic rock. The magma may move upward, propelled by its own lower density,
either melting and combining with the overlying layers or forcing them aside. This results in an intrusive
rock. If the melt erupts onto the surface it cools rapidly and the minerals form little or no crystal matrix,
creating a volcanic or extrusive rock.

1-2

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

Plutonic (Intrusive) Rocks
1-15. Slow crystallization from deeply buried magmas generally means good climbing, since the minerals
formed are relatively large and interwoven into a solid matrix. Weathering develops protrusions of resistant
minerals, which makes for either a rough-surfaced rock with excellent friction, or, if the resistant crystals
are much larger than the surrounding matrix, a surface with numerous knobby holds. Pieces of foreign rock
included in the plutonic body while it was rising and crystallizing, or clusters of segregated minerals, may
weather differently than the main rock mass and form chicken heads.

Intrusions are named according to location and size. Large (100 square kilometers or larger)
masses of plutonic rock are called batholiths and small ones stocks. Most plutonic rock is in the
granite family, differing only in the amounts of constituent minerals contained. A core of such
batholiths is in every major mountain system in the world. In the Alps, Sierras, North Cascades,
Rockies, Adirondacks, and most other ranges this core is at least partly exposed.

Small plutonic intrusions are stocks, forced between sedimentary strata, and dikes, which cut
across the strata. Many of these small intrusive bodies are quickly cooled and thus may look like
extrusive rock.

Volcanic (Extrusive) Rocks
1-16. Explosive eruptions eject molten rock so quickly into the air that it hardens into loose aerated masses
of fine crystals and uncrystallized glass (obsidian). When this ash consolidates while molten or after
cooling, it is called tuff, a weak rock that breaks down quickly and erodes easily. Quieter eruptions, where
widespread lava flows from large fissures, produce basalt. Basaltic rocks are fine-grained and often
sharp-edged.

Jointing Rocks
1-17. In plutonic rocks, joints or cracks are caused by internal stresses such as contraction during cooling
or expansion when overlying rock erodes or exfoliates. Some joints tend to follow a consistent pattern
throughout an entire mountain and their existence can often be predicted. Therefore, when a ledge suddenly
ends, the joint―and thus the ledge―may begin again around the corner. When molten rock extrudes onto
the surface as a lava flow or intrudes into a cold surrounding mass as a dike or sill, the contraction from
rapid cooling usually causes so much jointing that climbing can be extremely hazardous. Occasionally, this
jointing is regular enough to create massed pillars with usable vertical cracks such as Devil’s Tower in
Wyoming.

Sedimentary Rocks
1-18. Sedimentary rocks are born high in the mountains, where erosion grinds down debris and moves it
down to rivers for transportation to its final deposition in valleys, lakes, or oceans. As sediments
accumulate, the bottom layers are solidified by pressure and by mineral cements precipitated from
percolating groundwater. Gravel and boulders are transformed into conglomerates; sandy beaches into
sandstone; beds of mud into mudstone or shale; and shell beds and coral reefs into limestone or dolomite.

Though in general sedimentary rocks are much more friable than those cooled from molten
magmas, pressure and cementing often produce solid rocks. In fact, by sealing up internal cracks,
cementing can result in flawless surfaces, especially in limestone.

Most high mountain ranges have some sedimentary peaks. Ancient seafloor limestone can be
found on the summits of the Himalayas and the Alps. The Canadian Rockies are almost
exclusively limestone. With the exception of the Dolomites, in general sedimentary rocks do not
offer high-angle climbing comparable to that of granite.

METAMORPHIC ROCKS
1-19. These are igneous or sedimentary rocks that have been altered physically and or chemically by the
tremendous heat and pressures within the earth. After sediments are solidified, high heat and pressure can
cause their minerals to recrystallize. The bedding planes (strata) may also be distorted by folding and
squeezing. Shale changes to slate or schist, sandstone and conglomerate into quartzite, and limestone to

26 July 2012

TC 3-97.61

1-3

Chapter 1

marble. These changes may be minimal, only slightly altering the sediments, or extensive enough to
produce gneiss, which is almost indistinguishable from igneous rock.

Metamorphic rocks may have not only joints and bedding, but cleavage or foliation, a series of
thinly spaced cracks caused by the pressures of folding. Because of this cleavage, lower grades
of metamorphic rocks may be completely unsuitable for climbing because the rock is too rotten
for safe movement.

Higher degrees of metamorphism or metamorphism of the right rocks provide a solid climbing
surface. The Shawangunks of New York are an excellent example of high-grade conglomerate
quartzite, which offers world class climbing. The center of the Green Mountain anticline
contains heavily metamorphosed schist, which also provides solid climbing.

MOUNTAIN BUILDING
1-20. The two primary mechanisms for mountain-building are volcanic and tectonic activity. Volcanoes
are constructed from lava and ash, which begin within the earth as magma. Tectonic activity causes plates
to collide, heaving up fold mountains, and to pull apart and crack, forming fault-block mountain ranges.

PLATE TECTONICS
1-21. The massive slabs composing the outer layer are called tectonic plates. These plates are made up of
portions of lighter, granitic continental crust, and heavier, basaltic oceanic crust attached to slabs of the
rigid upper mantle. Floating slowly over the more malleable asthenosphere, their movement relative to
each other creates earthquakes, volcanoes, ocean trenches, and mountain ridge systems.

MOUNTAIN STRUCTURE
1-22. The different horizontal and vertical stresses that create mountains usually produce complex patterns.
Each type of stress produces a typical structure, and most mountains can be described in terms of these
structures.

Dome Mountains
1-23. A simple upward bulge of the crust forms dome mountains such as the Ozarks of Arkansas and
Missouri, New York’s Adirondacks, the Olympics of Washington, and the High Uintahs of Utah. They are
usually the result of the upward movement of magma and the folding of the rock layers overhead. Erosion
may strip away the overlying layers, exposing the central igneous core.

Fault-Block Mountains
1-24. Faulting, or cracking of the crust into large chunks, often accompanies upwarp, which results in
fault-block mountains. Many forms are created by the motion of these chunks along these faults.

The ranges of the desert country of California, Nevada, and Utah provide the clearest display of
faulting. The breakage extends to the surface and often during earthquakes―caused by slippage
between the blocks―fresh scarps many feet high develop.

Sometimes a block is faulted on both sides and rises or falls as a unit. More often, however, it is
faulted on one side only. The Tetons of Wyoming and the Sierra Nevada display this―along the
single zone of faults the range throws up impressive steep scarps, while on the other side the
block bends but does not break, leaving a gentler slope from the base of the range to the crest.
An example of a dropped block is California’s Death Valley, which is below sea level and could
not have been carved by erosion.

Fold Mountains
1-25. Tectonic forces, in which continental plates collide or ride over each other, have given rise to the
most common mountain form―fold mountains. Geologists call folds geosynclines. Upward folded strata
are anticlines and downward folds are synclines. When erosion strips down the overburden of rock from
folded mountain ranges, the oldest, central core is all that remains. The Alps and the Appalachians are

1-4

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

examples of fold mountains. When the squeezing of a range is intense, the rocks of the mountain mass first
fold but then may break, and parts of the rocks are pushed sideways and override neighboring formations.
This explains why older rocks are often found perched on top of younger ones. Isolated blocks of the over
thrust mass may form when erosion strips away links connecting them with their place of origin. Almost
every range of folded mountains in the world exhibits an over thrust of one sort or another.

Volcanic Mountains
1-26. Along convergent plate boundaries volcanic activity increases. As it is forced underneath an
overriding neighbor, continental crust melts and turns to magma within the mantle. Since it is less dense
than the surrounding material, it rises and erupts to form volcanoes.

These volcanoes are found in belts, which correspond to continental margins around the world.
The best known is the “Ring of Fire” encircling the Pacific Ocean from Katmai in Alaska
through the Cascades (Mount Rainier and Mount Saint Helens) down through Mexico’s
Popocatepetl to the smokes of Tierra del Fuego. This belt then runs west down the Aleutian
chain to Kamchatka, south to the volcanoes of Japan and the Philippines, and then east through
New Guinea into the Pacific. Smaller volcanic belts are found along the Indonesian-Southeast
Asian arc, the Caucasus region, and the Mediterranean.

Volcanic activity also arises at boundaries where two plates are moving away from each other,
creating deep rifts and long ridges where the crust has cracked apart and magma wells up to
create new surface material. Examples of this are the Mid-Atlantic Ridge, which has created
Iceland and the Azores, and the Rift Valley of East Africa with Kilimanjaro’s cone.

Complex Mountains
1-27. Most ranges are complex mountains with portions that have been subject to several processes. A
block may have been simply pushed upward without tilting, with other portions folded, domed, and faulted,
often with a sprinkling of volcanoes. In addition, these processes occur both at the macro and the micro
level. One massive fold can make an entire mountain peak; however, there are folds measured by a rope
length, and tiny folds found within a handhold. A mountain front may be formed from a single fault, but
smaller faults that form ledges and gullies may also be present.

ROUTE CLASSIFICATION
1-28. Military mountaineers must be able to assess a vertical obstacle, develop a course of action to
overcome the obstacle, and have the skills to accomplish the plan. Assessment of a vertical obstacle
requires experience in the classifications of routes and understanding the levels of difficulty they represent.
Without a solid understanding of the difficulty of a chosen route, the mountain leader can place his life and
the life of other Soldiers in extreme danger. Ignorance is the most dangerous hazard in the mountain
environment.
1-29. In North America the Yosemite Decimal System (YDS) is used to rate the difficulty of routes in
mountainous terrain. The YDS classes are—

Class 1―Hiking trail.

Class 2―Off-trail scramble.

Class 3―Climbing, use of ropes for beginners (moderate scrambling).

Class 4―Belayed climbing (moderate to difficult scrambling, which may have some exposure).

Class 5―Free climbing (requires climbers to be roped up, belay and emplace intermediate
protection).

Class 5 is further subdivided:

Class 5.0-5.4―Little Difficulty. This is the simplest form of free climbing. Hands are
necessary to support balance. This is sometimes referred to as advanced rock scrambling.

Class 5.5―Moderate Difficulty. Three points of contact are necessary.

Class 5.6―Medium Difficulty. The climber can experience vertical position or overhangs
where good grips can require moderate levels of energy expenditure.

26 July 2012

TC 3-97.61

1-5

Chapter 1











Class 5.7―Great Difficulty. Considerable climbing experience is necessary. Longer
stretches of climbing requiring several points of intermediate protection. Higher levels of
energy expenditure will be experienced.
Class 5.8 Very Great Difficulty. Increasing amount of intermediate protection is the rule.
High physical conditioning, climbing technique, and experience required.
Class 5.9 Extremely Great Difficulty. Requires well above average ability and excellent
condition. Exposed positions, often combined with small belay points. Passages of the
difficult sections can often be accomplished under good conditions. Often combined with
aid climbing (A0-A4).
Class 5.10 Extraordinary Difficulty. Climb only with improved equipment and intense
training. Besides acrobatic climbing technique, mastery of refined security technique is
indispensable. Often combined with aid climbing (A0-A4).
Class 5.11-5.14 Greater Increases Of Difficulty. Requires more climbing ability,
experience, and energy expenditure. Only talented and dedicated climbers reach this level.

1-30. Additional classifications include the following:

Classes are further divided into a, b, c, and d categories starting from 5.10 to 5.14, for
example, 5.10d.

Classes are also further divided from 5.9 and below with +/- categories, for example, 5.8+.

All Class 5 climbs can also be designated with “R” or “X,” which indicates a run-out on a climb.
This means that placement of intermediate protection is not possible on portions of the route. For
example, in a classification of 5.8R, the “R” indicates periods of run-out where, if a fall was
experienced, ground fall would occur. Always check the local guidebook to find specific
designation for your area.

All Class 5 climbs can also be designated with “stars.” These refer to the popularity of the climb
to the local area. Climbs are represented by a single star up to five stars; a five-star climb is a
classic climb and is usually aesthetically pleasing.
1-31. Aid climb difficulty classification includes the following: Aid climbing classes are also further
divided into plus or minus categories, such as A3+ or A3-, which simply means easy or hard:

1-6

A0

French-Free. This technique involves using a piece of gear to make progress such as clipping
a sling into a bolt or piece of protection, and then pulling up on it or stepping up in the sling.
Usually this is only needed to get past one or two more difficult moves on advanced free
climbs.

A1

Easy Aid. The placement of protection is straightforward and reliable. There is usually no
high risk of any piece of protection pulling out. This technique requires etriers and is fast and
simple.

A2

Moderate Aid. The placement of protection is generally straightforward, but placement can
be awkward and strenuous. Usually A2 involves one or two moves that are difficult with good
protection placement below and above the difficult moves, but no serious fall danger.

A3

Hard Aid. This technique requires testing your protection. It involves several awkward and
strenuous moves in a row. Generally solid placements which will hold a fall and are found
within a full rope length. However, long fall potential does exist, with falls of 40 to 60 feet and
intermediate protection on the awkward placements failing. These falls, however, are usually
clean and with no serious bodily harm.

A4

Serious Aid. This technique requires lots of training and practice. It is more like walking on
eggs so none of them break. Leads will usually take extended amounts of time, which causes
the lead climber to doubt and worry about each placement. Protection placed will usually only
hold a climber’s weight and falls can be as long as two-thirds the rope length.

A5

Extreme Aid. All protection is sketchy at best. Usually no protection placed on the entire
route can be trusted to stop a fall.

A6

Extremely Severe Aid. Continuous A5 climbing with A5 belay stations. If the leader falls, the

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

whole rope team will probably experience ground fall.
1-32. Grade ratings (commitment grades) inform the climber of the approximate time a climber trained to
the level of the climb will take to complete the route.
I
II
III
IV
V
VI

Several hours.
Half of a day.
About three-fourths of a day.
Long hard day (usually not less than 5.7).
1 1/2 to 2 1/2 days (usually not less than 5.8).
Greater than 2 days.

1-33. Climbing difficulties are rated by different systems, defined below and compared in Table 1-1.
YDS (Yosemite Decimal System)
UIAA (Union des International Alpine
Association)
British

French
Brazilian
Australian

26 July 2012

Used in the United States.
Used in Europe.
The British use adjectives and numbers to designate the
difficulty of climbs. This system can be confusing if the
climber is unfamiliar with it.
The French use numbers and letters to designate the difficulty
of climbs.
Brazil uses Roman Numerals and adjectives to designate
difficulty.
Australia uses only numbers to designate difficulty.

TC 3-97.61

1-7

Chapter 1

Table 1-1. Comparison of rating systems.
YDS
Class 1
Class 2
Class 3
Class 4
5.0
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10a
5.10b
5.10c
5.10d
5.11a
5.11b
5.11c
5.12a
5.12b
5.12c
5.12d

UIAA
I
II
III
III –
III
III +
IV –
IV
IV +
V–
V
V+
VI –
VI
VII –
VII
VII
VII +
VIII –
VIII
VIII
IX –
IX
IX
IX +

BRITISH
Easy (E)
Easy (E)
Easy (E)
Moderate (MOD)
Moderate (MOD)
Difficult (DIFF)
Hard difficult
Very difficult
Hard very difficult
Mild severe
Severe, hard severe, 4a
Severe, hard severe, 4b
Hard severe,
hard very severe, 4c
5a
E1, 5b
E1, 5b
E1, 5b
E1/E2, 5b-5c
E3, 6a
E3/E4, 6a
E4, 6b
E5, E6/7, 6c
E5, E6/7, 6c
E5, E6/7, 6c
E6/7, 7a

FRENCH

1a, b, c
1a, b, c
2a, b
2a, b
2c, 3a
3b, c, 4a
3b, c, 4a
3b, c, 4a
4a, b, c
4a, b, c
5a, b
5b, c
5b, c
5b, c
5b, c
5b, c
6a, b, c
6a, b, c
6a, b, c
7a
7a
7a
7a

BRAZIL

AUSTRALIA

II
IIsup
III
IIIsup
IV

4
5
6
7
8, 9
10, 11
12, 13
14
15

IVsup
V
Vsup
VI
VIsup
VII
VII
VIIsup
VIII
VIIIsup

16, 17
18
19
20
21
22
23
24
26
27
28
29

1-34. Ice climbing ratings can have commitment ratings and technical ratings. The numerical ratings are
often prefaced with WI (waterfall ice), AI (alpine ice), or M (mixed rock and ice).

Commitment Ratings
1-35. Commitment ratings are expressed in Roman numerals.
I
II
III

IV

1-8

A short, easy climb near the road, with no avalanche hazard and a straightforward descent.
A route of one or two pitches within a short distance of rescue assistance, with little objective
hazard.
A multipitch route at low elevation, or a one-pitch climb with an approach that takes about an
hour. The route requires anywhere from a few hours to a long day to complete. The descent
may require building rappel anchors, and the route might be prone to avalanche.
A multipitch route at higher elevations; may require several hours of approach on skis or foot.
This route is subject to objective hazards, possibly with a hazardous descent.

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

V

VI

VII

A long climb in a remote setting, requiring all day to complete the climb itself. Requires many
rappels off anchors for the descent. This route has sustained exposure to avalanche or other
objective hazards.
A long ice climb in an alpine setting, with sustained technical climbing. Only elite climbers
will complete it in a day. A difficult and involved approach and descent, with objective hazards
ever-present, all in a remote area.
Everything a grade VI has, and more of it. Possibly days to approach the climb, and objective
hazards rendering survival as questionable. Difficult physically and mentally.

Technical Ratings
1-36. Technical ratings are expressed as Arabic numerals.
1
2
3
4
5

6
7
8

A frozen lake or stream bed.
A pitch with short sections of ice up to 80 degrees; lots of opportunity for protection and good
anchors.
Sustained ice up to 80 degrees; the ice is usually good, with places to rest, but it requires skill
at placing protection and setting anchors.
A sustained pitch that is vertical or slightly less than vertical; may have special features such as
chandeliers and run-outs between protection.
A long, strenuous pitch, possibly 50 meters of 85- to 90-degree ice, with few if any rests
between anchors. The pitch may be shorter, but on featureless ice. Good skills at placing
protection are required.
A full 50-meter pitch of dead vertical ice, possibly of poor quality; requires efficiency of
movement and ability to place protection while in awkward stances.
A full rope length of thin vertical or overhanging ice of dubious adhesion. An extremely tough
pitch, physically and mentally, requiring agility and creativity.
Simply the hardest ice climbing ever done; extremely bold and gymnastic.

CROSS-COUNTRY MOVEMENT
1-37. Soldiers must know the terrain to determine the feasible routes for cross-country movement when no
roads or trails are available.

A pre-operations intelligence effort should include topographic and photographic map coverage
as well as detailed weather data for the area of operations. When planning mountain operations,
additional information may be needed about size, location, and characteristics of landforms;
drainage; types of rock and soil; and the density and distribution of vegetation. Control must be
decentralized to lower levels because of varied terrain, erratic weather, and communication
problems inherent to mountainous regions.

Movement is often restricted due to terrain and weather. The erratic weather requires that
Soldiers be prepared for wide variations in temperature, types, and amounts of precipitation.
1-38. Movement above the timberline reduces the amount of protective cover available at lower elevations.
The logistical problem is important; therefore, each man must be self-sufficient to cope with normal
weather changes using materials from his rucksack.
1-39. Movement during a storm is difficult due to poor visibility and bad footing on steep terrain. Although
the temperature is often higher during a storm than during clear weather, the dampness of rain and snow
and the penetration of wind cause Soldiers to chill quickly. Although climbers should get off the high
ground and seek shelter and warmth, if possible, during severe mountain storms, capable commanders may
use reduced visibility to achieve tactical surprise.

When the tactical situation requires continued movement during a storm, the following
precautions should be observed:
—
Maintain visual contact.

26 July 2012

TC 3-97.61

1-9

Chapter 1

—

—

—
—
—

—
—

Keep warm. Maintain energy and body heat by eating and drinking often; carry food that
can be eaten quickly and while on the move.
Keep dry. Wear wet-weather clothing when appropriate, but do not overdress, which can
cause excessive perspiration and dampen clothing. As soon as the objective is reached and
shelter secured, put on dry clothing.
Do not rush. Hasty movement during storms leads to breaks in contact and accidents.
If lost, stay warm, dry, and calm.
Do not use ravines as routes of approach during a storm as they often fill with water and are
prone to flash floods.
Avoid high pinnacles and ridgelines during electrical storms.
Avoid areas of potential avalanche or rock-fall danger.

COVER AND CONCEALMENT
1-40. When moving in the mountains, outcroppings, boulders, heavy vegetation, and intermediate terrain
can provide cover and concealment. Digging fighting positions and temporary fortifications is difficult
because soil is often thin or stony. The selection of dug-in positions requires detailed planning. Some rock
types, such as volcanic tuff, are easily excavated. In other areas, boulders and other loose rocks can be used
for building hasty fortifications. In alpine environments, snow and ice blocks may be cut and stacked to
supplement dug-in positions. As in all operations, positions and routes must be camouflaged to blend in
with the surrounding terrain to prevent aerial detection.

OBSERVATION
1-41. Observation in mountains varies because of weather and ground cover. The dominating height of
mountainous terrain permits excellent long-range observation. However, rapidly changing weather with
frequent periods of high winds, rain, snow, sleet, hail, and fog can limit visibility. The rugged nature of the
terrain often produces dead space at midranges.

Low cloud cover at higher elevations may neutralize the effectiveness of OPs established on
peaks or mountaintops. High wind speeds and sound often mask the noises of troop movement.
Several OPs may need to be established laterally, in depth, and at varying altitudes to provide
visual coverage of the battle area.

Conversely, the nature of the terrain can be used to provide concealment from observation. This
concealment can be obtained in the dead space. Mountainous regions are subject to intense
shadowing effects when the sun is low in relatively clear skies. The contrast from lighted to
shaded areas causes visual acuity in the shaded regions to be considerably reduced. These
shadowed areas can provide increased concealment when combined with other camouflage and
should be considered in maneuver plans.

FIELDS OF FIRE
1-42. Fields of fire, like observation, are excellent at long ranges. However, dead space is a problem at
short ranges. When forces cannot be positioned to cover dead space with direct fires, mines and obstacles
or indirect fire must be used. Range determination is deceptive in mountainous terrain. Soldiers must
routinely train in range estimation in mountainous regions to maintain their proficiency.

SECTION II. MOUNTAIN WEATHER
1-43. Most people subconsciously forecast the weather. If they look outside and see dark clouds they may
decide to take rain gear. If an unexpected wind strikes, people glance to the sky for other bad signs. A
conscious effort to follow weather changes will ultimately lead to a more accurate forecast. An analysis of
mountain weather and how it is affected by mountain terrain shows that such weather is prone to patterns
and is usually severe, but patterns are less obvious in mountainous terrain than in other areas. Conditions
greatly change with altitude, latitude, and exposure to atmospheric winds and air masses. Mountain weather
can be extremely erratic. It varies from stormy winds to calm, and from extreme cold to warmth within a

1-10

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

short time or with a minor shift in locality. The severity and variance of the weather causes it to have a
major impact on military operations.

CONSIDERATIONS FOR PLANNING
1-44. Mountain weather can be either a dangerous obstacle to operations or a valuable aid, depending on
how well it is understood and to what extent advantage is taken of its peculiar characteristics.

Weather often determines the success or failure of a mission since it is highly changeable.
Military operations plans must be flexible, especially in planning airmobile and airborne
operations. The weather must be anticipated to allow enough time for planning so that the
leaders of subordinate units can use their initiative in turning an important weather factor in their
favor. The clouds that often cover the tops of mountains and the fogs that cover valleys are an
excellent means of concealing movements that normally are made during darkness or in smoke.
Limited visibility can be used as a combat multiplier.

The safety or danger of almost all high mountain regions, especially in winter, depends upon a
change of a few degrees of temperature above or below the freezing point. Ease and speed of
travel depend mainly on the weather. Terrain that can be crossed swiftly and safely one day may
become impassable or highly dangerous the next due to snowfall, rainfall, or a rise in
temperature. The reverse can happen just as quickly. The prevalence of avalanches depends on
terrain, snow conditions, and weather factors.

Some mountains, such as those found in desert regions, are dry and barren, with temperatures
ranging from extreme heat in the summer to extreme cold in the winter. In tropical regions, lush
jungles with heavy seasonal rains and little temperature variation often cover mountains. High
rocky crags with glaciated peaks can be found in mountain ranges at most latitudes along the
western portion of the Americas and Asia.

Severe weather may decrease morale and increase basic survival problems. These problems can
be minimized when men have been trained to accept the weather by being self-sufficient.
Mountain Soldiers properly equipped and trained can use the weather to their advantage in
combat operations.

MOUNTAIN AIR
1-45. High mountain air is dry and may be drier in the winter. Cold air has a reduced capacity to hold
water vapor. Because of this increased dryness, equipment does not rust as quickly and organic material
decomposes slowly. The dry air also requires Soldiers to increase consumption of water. The reduced water
vapor in the air causes an increase in evaporation of moisture from the skin and in loss of water through
transpiration in the respiratory system. Due to the cold, most Soldiers do not naturally consume the quantity
of fluids they would at higher temperatures and must be encouraged to consciously increase their fluid
intake.

Pressure is low in mountainous areas due to the altitude. The barometer usually drops 2.5
centimeters for every 300 meters gained in elevation (3 percent).

The air at higher altitudes is thinner as atmospheric pressure drops with the increasing altitude.
The altitude has a natural filtering effect on the sun’s rays. Rays are absorbed or reflected in part
by the molecular content of the atmosphere. This effect is greater at lower altitudes. At higher
altitudes, the thinner, drier air has a reduced molecular content and, consequently, a reduced
filtering effect on the sun’s rays. The intensity of both visible and ultraviolet rays is greater with
increased altitude. These conditions increase the chance of sunburn, especially when combined
with a snow cover that reflects the rays upward.

WEATHER CHARACTERISTICS
1-46. The earth is surrounded by an atmosphere that is divided into several layers. The world’s weather
systems are in the lower of these layers known as the troposphere. This layer reaches as high as 40,000
feet. Weather is a result of an atmosphere, oceans, land masses, unequal heating and cooling from the sun,
and the earth’s rotation. The weather found in any one place depends on many things such as the air

26 July 2012

TC 3-97.61

1-11

Chapter 1

temperature, humidity (moisture content), air pressure (barometric pressure), how it is being moved, and if
it is being lifted or not.
1-47. Air pressure is the weight of the atmosphere at any given place. The higher the pressure, the better
the weather will be. With lower air pressure, the weather will more than likely be worse. In order to
understand this, imagine that the air in the atmosphere acts like a liquid. Areas with a high level of this
liquid exert more pressure on an area and are called high-pressure areas. Areas with a lower level are called
low-pressure areas. The average air pressure at sea level is 29.92 inches of mercury (hg) or 1,013 millibars
(mb). The higher in altitude, the lower the pressure.

HIGH PRESSURE
1-48. The characteristics of a high-pressure area are as follows:

The airflow is clockwise and out.

Otherwise known as an anticyclone.

Associated with clear skies.

Generally the winds will be mild.

Depicted as a blue “H” on weather maps.

LOW PRESSURE
1-49. The characteristics of a low-pressure area are as follows:

The airflow is counterclockwise and in.

Otherwise known as a cyclone.

Associated with bad weather.

Depicted as a red “L” on weather maps.
1-50. Air from a high-pressure area is basically trying to flow out and equalize its pressure with the
surrounding air. Low pressure, on the other hand, is building up vertically by pulling air in from outside
itself, which causes atmospheric instability resulting in bad weather.
1-51. On a weather map, these differences in pressure are shown as isobars. Isobars resemble contour lines
and are measured in either millibars or inches of mercury. The areas of high pressure are called “ridges”
and lows are called troughs.

WIND
1-52. In high mountains, the ridges and passes are seldom calm; however, strong winds in protected
valleys are rare. Normally, wind speed increases with altitude since the earth’s frictional drag is strongest
near the ground. This effect is intensified by mountainous terrain. Winds are accelerated when they
converge through mountain passes and canyons. Because of these funneling effects, the wind may blast
with great force on an exposed mountainside or summit. Usually, the local wind direction is controlled by
topography.
1-53. The force exerted by wind quadruples each time the wind speed doubles; that is, wind blowing at 40
knots pushes four times harder than a wind blowing at 20 knots. With increasing wind strength, gusts
become more important and may be 50 percent higher than the average wind speed. When wind strength
increases to a hurricane force of 64 knots or more, Soldiers should lay on the ground during gusts and
continue moving during lulls. If a hurricane- force wind blows where there is sand or snow, dense clouds
fill the air. The rocky debris or chunks of snow crust are hurled near the surface. During the winter season,
or at high altitudes, commanders must be constantly aware of the wind-chill factor and associated
cold-weather injuries (see Chapter 2).
1-54. Winds are formed due to the uneven heating of the air by the sun and rotation of the earth. Much of
the world’s weather depends on a system of winds that blow in a set direction.

1-12

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

1-55. Above hot surfaces, air expands and moves to colder areas where it cools and becomes denser, and
sinks to the earth’s surface. The results are a circulation of air from the poles along the surface of the earth
to the equator, where it rises and moves to the poles again.
1-56. Heating and cooling together with the rotation of the earth causes surface winds. In the Northern
Hemisphere, there are three prevailing winds:

POLAR EASTERLIES
1-57. These are winds from the polar region moving from the east. This is air that has cooled and settled at
the poles.

PREVAILING WESTERLIES
1-58. These winds originate from about 30 degrees north latitude from the west. This is an area where
prematurely cooled air, due to the earth’s rotation, has settled to the surface.

NORTHEAST TRADEWINDS
1-59. These are winds that originate from about 30o north from the northeast. The jet stream is a long
meandering current of high-speed winds often exceeding 250 miles per hour near the transition zone
between the troposphere and the stratosphere known as the tropopause. These winds blow from a generally
westerly direction dipping down and picking up air masses from the tropical regions and going north and
bringing down air masses from the polar regions. The patterns of wind mentioned above move air. This air
comes in parcels called air masses. These air masses can vary from the size of a small town to as large as a
country. These air masses are named from where they originate:

Maritime―over water.

Continental―over land.

Polar―north of 60o north latitude.

Tropical―south of 60o north latitude.
1-60. Combining these parcels of air provides the names and description of the four types of air masses:

Continental Polar―cold, dry air mass.

Maritime Polar―cold, wet air mass.

Maritime Tropical―warm, wet air mass.

Continental Tropical―warm, dry air mass.
1-61. Two types of winds are peculiar to mountain environments, but do not necessarily affect the weather.

ANABATIC WIND (VALLEY WINDS)
1-62. These winds blow up mountain valleys to replace warm rising air and are usually light winds.

KATABATIC WIND (MOUNTAIN WIND)
1-63. These winds blow down mountain valley slopes caused by the cooling of air and are occasionally
strong winds.

HUMIDITY
1-64. Humidity is the amount of moisture in the air. All air holds water vapor even if it cannot be seen. Air
can hold only so much water vapor; however, the warmer the air, the more moisture it can hold. When air
can hold all that it can the air is “saturated” or has 100 percent relative humidity.

If air is cooled beyond its saturation point, the air will release its moisture in one form or another
(clouds, fog, dew, rain, snow, and so on). The temperature at which this happens is called the
condensation point. The condensation point varies depending on the amount of water vapor
contained in the air and the temperature of the air. If the air contains a great deal of water,

26 July 2012

TC 3-97.61

1-13

Chapter 1



condensation can occur at a temperature of 68 degrees Fahrenheit, but if the air is dry and does
not hold much moisture, condensation may not form until the temperature drops to 32 degrees
Fahrenheit or even below freezing.
The adiabatic lapse rate is the rate at which air cools as it rises or warms as it descends. This rate
varies depending on the moisture content of the air. Saturated (moist) air will warm and cool
about 3.2 degrees Fahrenheit per 1,000 feet of elevation gained or lost. Dry air will warm and
cool about 5.5 degrees Fahrenheit per 1,000 feet of elevation gained or lost.

CLOUD FORMATION
1-65. Clouds are indicators of weather conditions. By reading cloud shapes and patterns, observers can
forecast weather with little need for additional equipment such as a barometer, wind meter, and
thermometer. Any time air is lifted or cooled beyond its saturation point (100 percent relative humidity),
clouds are formed. The four ways air gets lifted and cooled beyond its saturation point are as follows:

CONVECTIVE LIFTING
1-66. This effect happens due to the sun’s heat radiating off the Earth’s surface causing air currents
(thermals) to rise straight up and lift air to a point of saturation.

FRONTAL LIFTING
1-67. A front is formed when two air masses of different moisture content and temperature collide. Since
air masses will not mix, warmer air is forced aloft over the colder air mass. From there it is cooled and then
reaches its saturation point. Frontal lifting creates the majority of precipitation.

CYCLONIC LIFTING
1-68. An area of low pressure pulls air into its center from all over in a counterclockwise direction. Once
this air reaches the center of the low pressure, it has nowhere to go but up. Air continues to lift until it
reaches the saturation point.

OROGRAPHIC LIFTING
1-69. This happens when an air mass is pushed up and over a mass of higher ground such as a mountain.
Air is cooled due to the adiabatic lapse rate until the air’s saturation point is reached.

TYPES OF CLOUDS
1-70. Clouds are one of the signposts to what is happening with the weather. Clouds can be described in
many ways. They can be classified by height or appearance, or even by the amount of area covered
vertically or horizontally. Clouds are classified into five categories: low-, mid-, and high-level clouds;
vertically developed clouds; and less common clouds.

LOW-LEVEL CLOUDS
1-71. Low-level clouds (0 to 6,500 feet) are either cumulus or stratus (Figures 1-1 and 1-2). Low-level
clouds are mostly composed of water droplets since their bases lie below 6,500 feet. When temperatures are
cold enough, these clouds may also contain ice particles and snow.

The two types of precipitating low-level clouds are nimbostratus and stratocumulus (Figure 1-3
and Figure 1-4).
—
Nimbostratus clouds are dark, low-level clouds accompanied by light to moderately falling
precipitation. The sun or moon is not visible through nimbostratus clouds, which
distinguishes them from mid-level altostratus clouds. Due to the fog and falling
precipitation commonly found beneath and around nimbostratus clouds, their bases are
typically diffuse and difficult to accurately determine.

1-14

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

Stratocumulus clouds generally appear as low, lumpy layer of clouds that is sometimes
accompanied by weak precipitation. Stratocumulus clouds vary in color from dark gray to
light gray and may appear as rounded masses with breaks of clear sky between. Because the
individual elements of stratocumulus are larger than those of altocumulus, distinguishing
them is easier. With your arm extended toward the sky, altocumulus elements are about the
size of a thumbnail while stratocumulus are about the size of a fist.
Low-level clouds may be identified by their height above nearby surrounding relief of known
elevation. Most precipitation originates from low-level clouds because rain or snow usually
evaporate before reaching the ground from higher clouds. Low-level clouds usually indicate
impending precipitation, especially if the cloud is more than 3,000 feet thick. (Clouds that
appear dark at their bases are more than 3,000 feet thick.)
—



Low-Level Clouds

Figure 1-1. Cumulus clouds.

Figure 1-2. Stratus clouds.

Figure 1-3. Nimbostratus clouds.

Figure 1-4. Stratocumulus clouds.

MID-LEVEL CLOUDS
1-72. Mid-level clouds (between 6,500 to 20,000 feet) have a prefix of alto. Middle clouds appear less
distinct than low clouds because of their height. Alto clouds with sharp edges are warmer because they are
composed mainly of water droplets. Cold clouds, composed mainly of ice crystals and usually colder than
minus 30 degrees Fahrenheit, have distinct edges that grade gradually into the surrounding sky. Middle
clouds usually indicate fair weather, especially if they are rising over time. Lowering middle clouds
indicate potential storms, though usually hours away. There are two types of mid-level clouds, altocumulus
and altostratus clouds (Figures 1-5 and 1-6).

26 July 2012

TC 3-97.61

1-15

Chapter 1

Altocumulus
1-73. These can appear as parallel bands or rounded masses. Typically a portion of an altocumulus cloud is
shaded, a characteristic which makes them distinguishable from high-level cirrocumulus. Altocumulus
clouds usually form in advance of a cold front. The presence of altocumulus clouds on a warm humid
summer morning is commonly followed by thunderstorms later in the day. Altocumulus clouds that are
scattered rather than even, in a blue sky, are called “fair weather” cumulus and suggest arrival of high
pressure and clear skies.

Altostratus
1-74. These are often confused with cirrostratus. The one distinguishing feature is that a halo is not
observed around the sun or moon. With altostratus, the sun or moon is only vaguely visible and appears as
if it were shining through frosted glass.

Mid-Level Clouds

Figure 1-5. Altocumulus.

Figure 1-6. Altostratus.

HIGH-LEVEL CLOUDS
1-75. High-level clouds (more than 20,000 feet above ground level) are usually frozen clouds, indicating
air temperatures at that elevation below minus 30 degrees Fahrenheit, with a fibrous structure and blurred
outlines. The sky is often covered with a thin veil of cirrus that partly obscures the sun or, at night,
produces a ring of light around the moon. The arrival of cirrus indicates moisture aloft and the approach of
a traveling storm system. Precipitation is often 24 to 36 hours away. As the storm approaches, the cirrus
thickens and lowers, becoming altostratus and eventually stratus. Temperatures are warm, humidity rises,
and winds become southerly or south easterly. The two types of high-level clouds are cirrus and cirrostratus
(Figure 1-7 and Figure 1-8).

Cirrus
1-76. These are the most common of the high-level clouds. Typically found at altitudes greater than 20,000
feet, cirrus are composed of ice crystals that form when super-cooled water droplets freeze. Cirrus clouds
generally occur in fair weather and point in the direction of air movement at their elevation. Cirrus can be
observed in a variety of shapes and sizes. They can be nearly straight, shaped like a comma, or seemingly
all tangled together. Extensive cirrus clouds are associated with an approaching warm front.

Cirrostratus
1-77. These are sheet-like, high-level clouds composed of ice crystals. They are relatively transparent and
can cover the entire sky and be up to several thousand feet thick. The sun or moon can be seen through

1-16

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

cirrostratus. Sometimes the only indication of cirrostratus clouds is a halo around the sun or moon.
Cirrostratus clouds tend to thicken as a warm front approaches, signifying an increased production of ice
crystals. As a result, the halo gradually disappears and the sun or moon becomes less visible.
High-Level Clouds

Figure 1-7. Cirrus.

Figure 1-8. Cirrostratus.

Figure 1-9. Cumulonimbus.

Figure 1-10. Lenticular.

VERTICAL-DEVELOPMENT CLOUDS
1-78. Clouds with vertical development can grow to heights in excess of 39,000 feet, releasing incredible
amounts of energy. The two types of clouds with vertical development are fair weather cumulus and
cumulonimbus.

Fair Weather Cumulus
1-79. These have the appearance of floating cotton balls and have a lifetime of 5 to 40 minutes. Known for
their flat bases and distinct outlines, fair weather cumulus exhibit only slight vertical growth, with the cloud
tops designating the limit of the rising air. Given suitable conditions, however, these clouds can later
develop into towering cumulonimbus clouds associated with powerful thunderstorms. Fair weather cumulus
clouds are fueled by buoyant bubbles of air known as thermals that rise up from the earth’s surface. As the
air rises, the water vapor cools and condenses forming water droplets. Young fair weather cumulus clouds
have sharply defined edges and bases while the edges of older clouds appear more ragged, an artifact of
erosion. Evaporation along the cloud edges cools the surrounding air, making it heavier and producing
sinking motion outside the cloud. This downward motion inhibits further convection and growth of
additional thermals from down below, which is why fair weather cumulus typically have expanses of clear
sky between them. Without a continued supply of rising air, the cloud begins to erode and eventually
disappears.

26 July 2012

TC 3-97.61

1-17

Chapter 1

Cumulonimbus
1-80. These are much larger and more vertically developed than fair weather cumulus (see Figure 1-9).
They can exist as individual towers or form a line of towers called a squall line. Fueled by vigorous
convective updrafts, the tops of cumulonimbus clouds can reach 39,000 feet or higher. Lower levels of
cumulonimbus clouds consist mostly of water droplets while at higher elevations, where the temperatures
are well below freezing, ice crystals dominate the composition. Under favorable conditions, harmless fair
weather cumulus clouds can quickly develop into large cumulonimbus associated with powerful
thunderstorms known as super cells. Supercells are large thunderstorms with deep rotating updrafts and can
have a lifetime of several hours. Super cells produce frequent lightning, large hail, damaging winds, and
tornadoes. These storms tend to develop during the afternoon and early evening when the effects of heating
from the sun are the strongest.

OTHER CLOUD TYPES
1-81. These clouds are a collection of miscellaneous types that do not fit into the previous four groups.
They are orographic clouds, lenticulars, and contrails.

Orographic
1-82. These develop in response to the forced lifting of air by the earth’s topography. Air passing over a
mountain oscillates up and down as it moves downstream. Initially, stable air encounters a mountain, is
lifted upward, and cools. If the air cools to its saturation temperature during this process, the water vapor
condenses and becomes visible as a cloud. Upon reaching the mountain top, the air is heavier than the
environment and will sink down the other side, warming as it descends. Once the air returns to its original
height, it has the same buoyancy as the surrounding air. However, the air does not stop immediately
because it still has momentum carrying it downward. With continued descent, the air becomes warmer then
the surrounding air and accelerates back upwards towards its original height. Another name for this type of
cloud is the lenticular cloud.

Lenticular
1-83. These are cloud caps that often form above pinnacles and peaks, and usually indicate higher winds
aloft (Figure 1-10). Cloud caps with a lens shape, similar to a “flying saucer,” indicate extremely high
winds (over 40 knots). Lenticulars should always be watched for changes. If they grow and descend, bad
weather can be expected.

Contrails
1-84. These are clouds that are made by water vapor being inserted into the upper atmosphere by the
exhaust of jet engines (Figure 1-11). Contrails evaporate rapidly in fair weather. If it takes longer than two
hours for contrails to evaporate, then there is impending bad weather (usually about 24 hours prior
to a front).

1-18

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

Vertical-Development Clouds

Figure 1-11. Contrails.

CLOUD INTERPRETATION
1-85. Serious errors can occur in interpreting the extent of cloud cover, especially when cloud cover must
be reported to another location. Cloud cover always appears greater on or near the horizon, especially if the
sky is covered with cumulus clouds, since the observer is looking more at the sides of the clouds rather than
between them. Cloud cover estimates should be restricted to sky areas more than 40 degrees above the
horizon―that is, to the local sky. Assess the sky by dividing the 360 degrees of sky around you into
eighths. Record the coverage in eighths and the types of clouds observed.

FRONTS
1-86. Fronts occur when two air masses of different moisture and temperature contents meet. One of the
indicators that a front is approaching is the progression of the clouds. The four types of fronts are warm,
cold, occluded, and stationary.

26 July 2012

TC 3-97.61

1-19

Chapter 1

WARM FRONT
1-87. A warm front occurs when warm air moves into and over a slower or stationary cold air mass.
Because warm air is less dense, it will rise up and over the cooler air. The cloud types seen when a warm
front approaches are cirrus, cirrostratus, nimbostratus (producing rain), and fog. Occasionally,
cumulonimbus clouds will be seen during the summer months.

COLD FRONT
1-88. A cold front occurs when a cold air mass overtakes a slower or stationary warm air mass. Cold air,
being more dense than warm air, will force the warm air up. Clouds observed will be cirrus, cumulus, and
then cumulonimbus producing a short period of showers.

OCCLUDED FRONT
1-89. Cold fronts generally move faster than warm fronts. The cold fronts eventually overtake warm fronts
and the warm air becomes progressively lifted from the surface. The zone of division between cold air
ahead and cold air behind is called a cold occlusion. If the air behind the front is warmer than the air ahead,
it is a warm occlusion. Most land areas experience more occlusions than other types of fronts. The cloud
progression observed will be cirrus, cirrostratus, altostratus, and nimbostratus. Precipitation can be from
light to heavy.

STATIONARY FRONT
1-90. A stationary front is a zone with no significant air movement. When a warm or cold front stops
moving, it becomes a stationary front. Once this boundary begins forward motion, it once again becomes a
warm or cold front. When crossing from one side of a stationary front to another, there is typically a
noticeable temperature change and shift in wind direction. The weather is usually clear to partly cloudy
along the stationary front.

TEMPERATURE
1-91. Normally, a temperature drop of 3 to 5 degrees Fahrenheit for every 1,000 feet gain in altitude is
encountered in motionless air. For air moving up a mountain with condensation occurring (clouds, fog, and
precipitation), the temperature of the air drops 3.2 degrees Fahrenheit with every 1,000 feet of elevation
gain. For air moving up a mountain with no clouds forming, the temperature of the air drops 5.5 degrees
Fahrenheit for every 1,000 feet of elevation gain.

An expedient to this often occurs on cold, clear, calm mornings. During a troop movement or
climb started in a valley, higher temperatures may often be encountered as altitude is gained.
This reversal of the normal cooling with elevation is called temperature inversion. Temperature
inversions are caused when mountain air is cooled by ice, snow, and heat loss through thermal
radiation. This cooler, denser air settles into the valleys and low areas. The inversion continues
until the sun warms the surface of the earth or a moderate wind causes a mixing of the warm and
cold layers. Temperature inversions are common in the mountainous regions of the arctic,
subarctic, and mid-latitudes.

At high altitudes, solar heating is responsible for the greatest temperature contrasts. More
sunshine and solar heat are received above the clouds than below. The important effect of
altitude is that the sun’s rays pass through less of the atmosphere and more direct heat is
received than at lower levels, where solar radiation is absorbed and reflected by dust and water
vapor. Differences of 40 to 50 degrees Fahrenheit may occur between surface temperatures in
the shade and surface temperatures in the sun. This is particularly true for dark metallic objects.
The difference in temperature felt on the skin between the sun and shade is normally 7 degrees
Fahrenheit. Special care must be taken to avoid sunburn and snow blindness. Besides permitting
rapid heating, the clear air at high altitudes also favors rapid cooling at night. Consequently, the
temperature rises fast after sunrise and drops quickly after sunset. Much of the chilled air drains
downward, due to convection currents, so that the differences between day and night
temperatures are greater in valleys than on slopes.

1-20

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards



Local weather patterns force air currents up and over mountaintops. Air is cooled on the
windward side of the mountain as it gains altitude, but more slowly (3.2 degrees Fahrenheit per
1,000 feet) if clouds are forming due to heat release when water vapor becomes liquid. On the
leeward side of the mountain, this heat gained from the condensation on the windward side is
added to the normal heating that occurs as the air descends and air pressure increases. Therefore,
air and winds on the leeward slope are considerably warmer than on the windward slope, which
is referred to as Chinook winds. The heating and cooling of the air affects planning
considerations primarily with regard to the clothing and equipment needed for an operation.

WEATHER FORECASTING
1-92. The use of a portable aneroid barometer, thermometer, wind meter, and hygrometer help in making
local weather forecasts. Reports from other localities and from any weather service, including USAF, USN,
or the National Weather Bureau, are also helpful. Weather reports should be used in conjunction with the
locally observed current weather situation to forecast future weather patterns. Weather at various elevations
may be quite different because cloud height, temperature, and barometric pressure will all be different.
There may be overcast and rain in a lower area, with mountains rising above the low overcast into warmer
clear weather. To be effective, a forecast must reach the small-unit leaders who are expected to utilize
weather conditions for assigned missions. Several different methods can be used to create a forecast. The
method a forecaster chooses depends upon the forecaster’s experience, the amount of data available, the
level of difficulty that the forecast situation presents, and the degree of accuracy needed to make the
forecast. The five ways to forecast weather are—

PERSISTENCE METHOD
1-93. “Today equals tomorrow” is the simplest way of producing a forecast. This method assumes that the
conditions at the time of the forecast will not change; for example, if today was hot and dry, the persistence
method predicts that tomorrow will be the same.

TRENDS METHOD
1-94. “Nowcasting” involves determining the speed and direction of fronts, high- and low-pressure centers,
and clouds and precipitation. For example, if a cold front moves 300 miles during a 24-hour period, we can
predict that it will travel 300 miles in another 24-hours.

CLIMATOLOGY METHOD
1-95. This method averages weather statistics accumulated over many years. This only works well when
the pattern is similar to the following years.

ANALOG METHOD
1-96. This method examines a day’s forecast and recalls a day in the past when the weather looked similar
(an analogy). This method is difficult to use because finding a perfect analogy is difficult.

NUMERICAL WEATHER PREDICTION
1-97. This method uses computers to analyze all weather conditions and is the most accurate of the five
methods.

RECORDING DATA
1-98. An accurate observation is essential in noting trends in weather patterns. Ideally, under changing
conditions, trends will be noted in some weather parameters. However, this may not always be the case. A
minor shift in the winds may signal an approaching storm.

26 July 2012

TC 3-97.61

1-21

Chapter 1

WIND DIRECTION
1-99. Assess wind direction as a magnetic direction from which the wind is blowing.

WIND SPEED
1-100. Assess wind speed in knots.

If an anemometer is available, assess speed to the nearest knot.

If no anemometer is available, estimate the speed in knots. Judge the wind speed by the way
objects, such as trees, bushes, tents, and so forth, are blowing.

VISIBILITY IN METERS
1-101. Observe the farthest visible major terrain or man-made feature and determine the distance using
any available map.

PRESENT WEATHER
1-102. Include any precipitation or obscuring weather. The following are examples of present weather:

Rain―continuous and steady liquid precipitation that will last at least one hour.

Rain showers―short-term and potentially heavy downpours that rarely last more than one hour.

Snow―continuous and steady frozen precipitation that will last at least one hour.

Snow showers―short-term and potentially heavy frozen downpours that rarely last more than
one hour.

Fog, haze―obstructs visibility of ground objects.

Thunderstorms―a potentially dangerous storm. Thunderstorms will produce lightning, heavy
downpours, colder temperatures, tornadoes (not too frequently), hail, and strong gusty winds at
the surface and aloft. Winds commonly exceed 35 knots.

TOTAL CLOUD COVER
1-103. Assess total cloud cover in eighths. Divide the sky into eight different sections measuring from
horizon to horizon. Count the sections with cloud cover, which gives the total cloud cover in eighths. (For
example, if half of the sections are covered with clouds, total cloud cover is 4/8.)

CEILING HEIGHT
1-104. Estimate where the cloud base intersects elevated terrain. Note if bases are above all terrain. If
clouds are not touching terrain, then estimate to the best of your ability.

TEMPERATURE
1-105. Assess temperature with or without a thermometer. With a thermometer, assess temperature in
degrees Celsius (use Fahrenheit only if Celsius conversion is not available). To convert Fahrenheit to
Celsius: C = F minus 32 times .55. To convert Celsius to Fahrenheit: F = 1.8 times C plus 32.

Example:

41 degrees F – 32 x .55 = 5 degrees C
5 degrees C x 1.8 + 32 = 41 degrees F

1-106. Without a thermometer, estimate temperature as above or below freezing (0 degrees C), as well as
an estimated temperature.

PRESSURE TREND
1-107. With a barometer or altimeter, assess the pressure trend.

1-22

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards




A high pressure moving in will cause altimeters to indicate lower elevation.
A low pressure moving in will cause altimeters to indicate higher elevation.

OBSERVED WEATHER
1-108. Note changes or trends in observed weather conditions.

Deteriorating Trends











Marked wind direction shifts. A high pressure system wind flows clockwise. A low pressure
system wind flows counterclockwise. The closer the isometric lines are, the greater the
differential of pressure (greater wind speeds).
Marked wind speed increases.
Changes in obstructions to visibility.
Increasing cloud coverage.
Increase in precipitation. A steady drizzle is usually a long-lasting rain.
Lowering cloud ceilings.
Marked cooler temperature changes, which could indicate that a cold front is passing through.
Marked increase in humidity.
Decreasing barometric pressure, which indicates a lower pressure system is moving through
the area.

Improving Trends










Steady wind direction, which indicates no change in weather systems in the area.
Decreasing wind speeds.
Clearing of obstructions to visibility.
Decreasing or ending precipitation.
Decreasing cloud coverage.
Increasing height of cloud ceilings.
Temperature changes slowly warmer.
Humidity decreases.
Increasing barometric pressure, which indicates that a higher pressure system is moving through
the area.

UPDATE
1-109. Continue to evaluate observed conditions and update the forecast.

SECTION III. MOUNTAIN HAZARDS
1-110. Hazards can be termed natural (caused by natural occurrence), man-made (caused by an individual,
such as lack of preparation, carelessness, improper diet, equipment misuse), or as a combination (human
trigger). There are two kinds of hazards while in the mountains―subjective and objective. Combinations of
objective and subjective hazards are referred to as cumulative hazards.

SUBJECTIVE HAZARDS
1-111. Subjective hazards are created by humans; for example, choice of route, companions, overexertion,
dehydration, climbing above one’s ability, and poor judgment.

FALLING
1-112. Falling can be caused by carelessness, over-fatigue, heavy equipment, bad weather, overestimating
ability, a hold breaking away, or other reasons.

26 July 2012

TC 3-97.61

1-23

Chapter 1

BIVOUAC SITE
1-113. Bivouac sites must be protected from rockfall, wind, lightning, avalanche run-out zones, and
flooding (especially in gullies). If the possibility of falling exists, rope in, the tent and all equipment may
have to be tied down.

EQUIPMENT
1-114. Ropes are not total security; they can be cut on a sharp edge or break due to poor maintenance,
age, or excessive use. You should always pack emergency and bivouac equipment even if the weather
situation, tour, or a short climb is seemingly low of dangers.

OBJECTIVE HAZARDS
1-115. Objective hazards are caused by the mountain and weather and cannot be influenced by man, for
example, storms, rockfalls, icefalls, and lightning.

ALTITUDE
1-116. At high altitudes, especially over 6,500 feet, endurance and concentration is reduced. Cut down on
smoking and alcohol. Sleep well, acclimatize slowly, stay hydrated, and be aware of signs and symptoms of
high-altitude illnesses. Storms can form quickly and lightning can be severe.

VISIBILITY
1-117. Fog, rain, darkness, and or blowing snow can lead to disorientation. Take note of your exact
position and plan your route to safety before visibility decreases. Cold combined with fog can cause a thin
sheet of ice to form on rocks (verglas). Whiteout conditions can be extremely dangerous. If you must move
under these conditions, it is best to rope up. Have the point man move to the end of the rope. The second
man will use the first man as an aiming point with the compass. Use a route sketch and march table. If the
tactical situation does not require it, plan route so as not to get caught by darkness.

GULLIES
1-118. Rock, snow, and debris are channeled down gullies. If ice is in the gully, climbing at night may be
better because the warming of the sun will loosen stones and cause rockfalls.

ROCKFALL
1-119. Blocks and scree at the base of a climb can indicate recurring rockfall. Light colored spots on the
wall may indicate impact chips of falling rock. Spring melt or warming by the sun of the rock/ice/snow
causes rockfall.

AVALANCHES
1-120. Avalanches are caused by the weight of the snow overloading the slope. (Refer to paragraph 1-125
for more detailed information on avalanches.)

HANGING GLACIERS AND SERACS
1-121. Avoid, if at all possible, hanging glaciers and seracs. They will fall without warning regardless of
the time of day or time of year. One cubic meter of glacier ice weighs 910 kilograms (about 2,000 pounds).
If you must cross these danger areas, do so quickly and keep an interval between each person.

CREVASSES
1-122. Crevasses are formed when a glacier flows over a slope and makes a bend, or when a glacier
separates from the rock walls that enclose it. A slope of only two to three degrees is enough to form a

1-24

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

crevasse. As this slope increases from 25 to 30 degrees, hazardous icefalls can be formed. Likewise, as a
glacier makes a bend, it is likely that crevasses will form at the outside of the bend. Therefore, the safest
route on a glacier would be to the inside of bends, and away from steep slopes and icefalls. Extreme care
must be taken when moving off of or onto the glacier because of the moat that is most likely to be present.

WEATHER HAZARDS
1-123. Weather conditions in the mountains may vary from one location to another as little as 10
kilometers apart. Approaching storms may be hard to spot if masked by local peaks. A clear, sunny day in
July could turn into a snowstorm in less than an hour. Always pack some sort of emergency gear.

Winds are stronger and more variable in the mountains; as wind doubles in speed, the force
quadruples.

Precipitation occurs more on the windward side than the leeward side of ranges. This causes
more frequent and denser fog on the windward slope.

Above about 8,000 feet, snow can be expected any time of year in the temperate climates.

Air is dryer at higher altitudes, so equipment does not rust as quickly, but dehydration is of
greater concern.

Lightning is frequent, violent, and normally attracted to high points and prominent features in
mountain storms. Signs indicative of thunderstorms are tingling of the skin, hair standing on end,
humming of metal objects, crackling, and a bluish light (St. Elmo’s fire) on especially prominent
metal objects (summit crosses and radio towers).
—
Avoid peaks, ridges, rock walls, isolated trees, fixed wire installations, cracks that guide
water, cracks filled with earth, shallow depressions, shallow overhangs, and rock needles.
Seek shelter around dry, clean rock without cracks; in scree fields; or in deep indentations
(depressions, caves). Keep at least half a body’s length away from a cave wall and opening.
—
Assume a one-point-of-contact body position. Squat on your haunches or sit on a rucksack
or rope. Pull your knees to your chest and keep both feet together. If halfway up the rock
face, secure yourself with more than one point―lightning can burn through rope. If already
rappelling, touch the wall with both feet together and hurry to the next anchor.

During and after rain, expect slippery rock and terrain in general and adjust movement
accordingly. Expect flash floods in gullies or chimneys. A climber can be washed away or even
drowned if caught in a gully during a rainstorm. Be especially alert for falling objects that the
rain has loosened.

Dangers from impending high winds include frostbite (from increased wind-chill factor),
windburn, being blown about (especially while rappelling), and debris being blown about. Wear
protective clothing and plan the route to be finished before bad weather arrives.

For each 100-meter rise in altitude, the temperature drops about one degree Fahrenheit. This can
cause hypothermia and frostbite even in summer, especially when combined with wind, rain, and
snow. Always wear or pack appropriate clothing.

If it is snowing, gullies may contain avalanches or snow sloughs, which may bury the trail.
Snowshoes or skis may be needed in autumn or even late spring. Unexpected snowstorms may
occur in the summer with accumulations of 12 to 18 inches; however, the snow quickly melts.

Higher altitudes provide less filtering effects, which leads to greater ultraviolet (UV) radiation
intensity. Cool winds at higher altitudes may mislead one into underestimating the sun’s
intensity, which can lead to sunburns and other heat injuries. Use sunscreen and wear hat and
sunglasses, even if overcast. Drink plenty of fluids.

AVALANCHE HAZARDS
1-124. Avalanches occur when the weight of accumulated snow on a slope exceeds the cohesive forces
that hold the snow in place. (Table 1-2, page 1-30, shows an avalanche hazard evaluation checklist.)

26 July 2012

TC 3-97.61

1-25

Chapter 1

SLOPE STABILITY
1-125. Slope stability is the key factor in determining the avalanche danger.

Slope Angle
1-126. Slopes as gentle as 15 degrees have avalanched. Most avalanches occur on slopes between 30 and
45 degrees. Slopes above 60 degrees often do not build up significant quantities of snow because they are
too steep.

Slope Profile
1-127. Dangerous slab avalanches are more likely to occur on convex slopes, but may occur on concave
slopes.

Slope Aspect
1-128. Snow on north facing slopes is more likely to slide in midwinter. South facing slopes are most
dangerous in the spring and on sunny, warm days. Slopes on the windward side are generally more stable
than leeward slopes.

Ground Cover
1-129. Rough terrain is more stable than smooth terrain. On grassy slopes or scree, the snow pack has
little to anchor to.

TRIGGERS
1-130. Various factors trigger avalanches.

Temperature
1-131. When the temperature is extremely low, settlement and adhesion occur slowly. Avalanches that
occur during extreme cold weather usually occur during or immediately following a storm. At a
temperature just below freezing, the snowpack stabilizes quickly. At temperatures above freezing,
especially if temperatures rise quickly, the potential for avalanche is high. Storms with a rise in temperature
can deposit dry snow early, which bonds poorly with the heavier snow deposited later. Most avalanches
occur during the warmer midday.

Precipitation
1-132. About 90 percent of avalanches occur during or within twenty-four hours after a snowstorm. The
rate at which snow falls is important. High rates of snowfall (2.5 centimeters per hour or greater),
especially when accompanied by wind, are usually responsible for major periods of avalanche activity.
Rain falling on snow will increase its weight and weakens the snowpack.

Wind
1-133. Sustained winds of 15 miles per hour and over transport snow and form wind slabs on the lee side
of slopes.

Weight
1-134. Most victims trigger the avalanches that kill them.

Vibration
1-135. Passing helicopters, heavy equipment, explosions, and earth tremors have triggered avalanches.

1-26

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards

SNOW PITS
1-136. Snow pits can be used to determine slope stability.

Dig the snow pit on the suspect slope or a slope with the same sun and wind conditions. Snow
deposits may vary greatly within a few meters due to wind and sun variations. (On at least one
occasion, a snow pit dug across the fall line triggered the suspect slope). Dig a 2-meter by
2-meter pit across the fall line, through all the snow, to the ground. Once the pit is complete,
smooth the face with a shovel.

Conduct a shovel shear test.
—
A shovel shear test puts pressure on a representative sample of the snowpack. The core of
this test is to isolate a column of the snowpack from three sides. The column should be of
similar size to the blade of the shovel. Dig out the sides of the column without pressing
against the column with the shovel (this affects the strength). To isolate the rear of the
column, use a rope or string to saw from side to side to the base of the column.
—
If the column remained standing while cutting the rear, place the shovel face down on the
top of the column. Tap with varying degrees of strength on the shovel to see what force it
takes to create movement on the bed of the column. The surface that eventually slides will
be the layer to look at closer. This test provides a better understanding of the snowpack
strength. For greater results you will need to do this test in many areas and formulate a scale
for the varying methods of tapping the shovel.

Conduct a Rutschblock test. To conduct the test, isolate a column slightly longer than the length
of your snowshoes or skis (same method as for the shovel shear test). One person moves on their
skis or snowshoes above the block without disturbing the block. Once above, the person
carefully places one showshoe or ski onto the block with no body weight for the first stage of the
test. The next stage is adding weight to the first leg. Next, place the other foot on the block. If
the block is still holding up, squat once, then twice, and so on. The remaining stage is to jump up
and land on the block.

TYPES OF SNOW AVALANCHES
1-137. There are two types of snow avalanches: loose snow (point) and slab.

Loose snow avalanches start at one point on the snow cover and grow in the shape of an inverted
“V.” Although they happen most frequently during the winter snow season, they can occur at
any time of the year in the mountains. They often fall as many small sluffs during or shortly after
a storm. This process removes snow from steep upper slopes and either stabilizes lower slopes or
loads them with additional snow.

Wet loose snow avalanches occur in spring and summer in all mountain ranges. Large
avalanches of this type, lubricated and weighed down by meltwater or rain can travel long
distances and have tremendous destructive power. Coastal ranges that have high temperatures
and frequent rain are the most common areas for this type of avalanche.

Slab avalanches occur when cohesive snow begins to slide on a weak layer. The fracture line
where the moving snow breaks away from the snowpack makes this type of avalanche easy to
identify. Slab release is rapid. Although any avalanche can kill you, slab avalanches are
generally considered more dangerous than loose snow avalanches.
—
Most slab avalanches occur during or shortly after a storm when slopes are loaded with new
snow at a critical rate. The old rule of never travel in avalanche terrain for a few days after a
storm still holds true.
—
As slabs become harder, their behavior becomes more unpredictable; they may allow
several people to ski across before releasing. Many experts believe they are susceptible to
rapid temperature changes. Packed snow expands and contracts with temperature changes.
For normal density, settled snow, a drop in temperature of 10 degrees Celsius (18 degrees
Fahrenheit) would cause a snow slope 300 meters wide to contract 2 centimeters. Early ski
mountaineers in the Alps noticed that avalanches sometimes occurred when shadows struck
a previously sun-warmed slope.

26 July 2012

TC 3-97.61

1-27

Chapter 1

PROTECTIVE MEASURES
1-138. Avoiding known or suspected avalanche areas is the easiest method of protection. Other measures
include—

Personal Safety
1-139. Remove your hands from ski pole wrist straps. Detach ski runaway cords. Prepare to discard
equipment. Put your hood on. Close up your clothing to prepare for hypothermia. Deploy avalanche cord.
Make avalanche probes and shovels accessible. Keep your pack on at all times—do not discard. Your pack
can act as a flotation device, as well as protect your spine.

Group Safety
1-140. Send one person across the suspect slope at a time with the rest of the group watching. All
members of the group should move in the same track from safe zone to safe zone.

ROUTE SELECTION
1-141. Selecting the correct route will help avoid avalanche prone areas, which is always the best choice.
Always allow a wide margin of safety when making your decision.

The safest routes are on ridge tops, slightly on the windward side; the next safest route is out in
the valley, far from the bottom of slopes.

Avoid cornices from above or below. Should you encounter a dangerous slope, either climb to
the top of the slope or descend to the bottom—well out of the way of the run-out zone. If you
must traverse, pick a line where you can traverse downhill as quickly as possible. When you
must ascend a dangerous slope, climb to the side of the avalanche path, and not directly up the
center.

Take advantage of dense timber, ridges, or rocky outcrops as islands of safety. Use them for
lunch and rest stops. Spend as little time as possible on open slopes.

Since most avalanches occur within twenty-four hours of a storm and or at midday, avoid
moving during these periods. Moving at night is tactically sound and may be safer.

STABILITY ANALYSIS
1-142. Look for nature’s billboards on slopes similar to the one you are on.

Evidence of Avalanching
1-143. Look for recent avalanches and for signs of wind-loading and wind-slabs.

Fracture Lines
1-144. Avoid any slopes showing cracks.

Sounds
1-145. Beware of hollow sounds—a “whumping” noise. They may suggest a radical settling of the
snowpack.

SURVIVAL
1-146. People trigger avalanches that bury people. If these people recognized the hazard and chose a
different route, they would avoid the avalanche. Follow these steps if caught in an avalanche:

Discard equipment. Equipment can injure or burden you; discarded equipment will also indicate
your position to rescuers.

1-28

TC 3-97.61

26 July 2012

Mountain Terrain, Weather, and Hazards










26 July 2012

Swim or roll to stay on tope of the snow. FIGHT FOR YOUR LIFE. Work toward the edge of
the avalanche. If you feel your feet touch the ground, give a hard push and try to “pop out” onto
the surface.
If your head goes under the snow, shut your mouth, hold your breath, and position your hands
and arms to form an air pocket in front of your face. Many avalanche victims suffocate by
having their mouths and noses plugged with snow.
When you sense the slowing of the avalanche, you must try your hardest to reach the surface.
Several victims have been found quickly because a hand or foot was sticking above the surface.
When the snow comes to rest it sets up like cement, and even if you are only partially buried, it
may be impossible to dig yourself out. Don’t shout unless you hear rescuers immediately above
you; in snow, no one can hear you scream. Don’t struggle to free yourself—you will only waste
energy and oxygen.
Try to relax. If you feel yourself about to pass out, do not fight it. The respiration of an
unconscious person is more shallow, and the pulse rate and body temperature are lower. All of
these factors reduce the amount of oxygen needed. (See Appendix C for information on search
and rescue techniques.)

TC 3-97.61

1-29

Chapter 1

Table 1-2. Avalanche hazard evaluation (GREEN-YELLOW-RED) checklist.

1-30

TC 3-97.61

26 July 2012

Chapter 2

Mountain Living
Units deploying to high elevations must receive advanced training to survive in the
harsh mountain environment. Normal activities (navigating, communicating, and
moving) require specialized techniques. Training should be conducted as realistically
as possible, preferably under severe conditions so the Soldier gains confidence.
Extended training exercises test support facilities and expose the Soldier to the
isolation common to mountain operations. Training should reflect the harsh mountain
environment and should consider the following:
• Temperature and altitude extremes.
• Hygiene and sanitation.
• Limited living space (difficulty of bivouac).
• Clothing requirements.

SECTION I. SURVIVAL
2-1. The Soldier trained to fight and survive in a mountain environment will have increased selfconfidence. Training should include psychological preparation; shelter considerations; health hazards; and
water-location, fire-building, and food-finding techniques (FM 3-05.70).

WATER SUPPLY
2-2. Mountain water should never be assumed safe for consumption. Training in water discipline should
be emphasized to ensure Soldiers drink water only from approved sources. Fluids lost through respiration,
perspiration, and urination must be replaced if the Soldier is to operate efficiently.

Maintaining fluid balance is a major problem in mountain operations. The sense of thirst may be
dulled by high elevations despite the greater threat of dehydration. Hyperventilation and the
cool, dry atmosphere bring about a three- to four-fold increase in water loss by evaporation
through the lungs. Hard work and overheating increase the perspiration rate. The Soldier must
make an effort to drink liquids even when he does not feel thirsty. One quart of water, or the
equivalent, should be drunk every four hours; more should be drunk if the unit is conducting
rigorous physical activity.

Three to six quarts of water each day should be consumed. About 75 percent of the human body
is liquid. All chemical activities in the body occur in water solution, which assists in removing
toxic wastes and in maintaining an even body temperature. A loss of two quarts of body fluid
(2.5 percent of body weight) decreases physical efficiency by 25 percent, and a loss of 12 quarts
(15 percent of body weight) is usually fatal. Salt lost by sweating should be replaced in meals to
avoid a deficiency and subsequent cramping. Consuming the usual military rations (three meals
a day) provides sufficient sodium replacement. Salt tablets are not necessary and may contribute
to dehydration.

Even when water is plentiful, thirst should be satisfied in increments. Quickly drinking a large
volume of water may actually slow the Soldier. If he is hot and the water is cold, severe
cramping may result. A basic rule is to drink small amounts often. Pure water should always be
kept in reserve for first aid use. Emphasis must be placed on the three rules of water discipline:
—
Drink only treated water.
—
Conserve water for drinking. Potable water in the mountains may be in short supply.
—
Do not contaminate or pollute water sources.

26 July 2012

TC 3-97.61

2-1

Chapter 2







Snow, mountain streams, springs, rain, and lakes provide good sources of water supply.
Purification must be accomplished, however, no matter how clear the snow or water appears.
Fruits, juices, and powdered beverages may supplement and encourage water intake (do not add
these until the water has been treated since the purification tablets may not work). Soldiers
cannot adjust permanently to a decreased water intake. If the water supply is insufficient,
physical activity must be reduced. Any temporary deficiency should be replaced to maintain
maximum performance.
All water that is to be consumed must be potable. Drinking water must be taken only from
approved sources or purified to avoid disease or the possible use of polluted water. Melting snow
into water requires an increased amount of fuel and should be planned accordingly. Nonpotable
water must not be mistaken for drinking water. Water that is unfit to drink, but otherwise not
dangerous, may be used for other purposes such as bathing. Soldiers must be trained to avoid
wasting water. External cooling (pouring water over the head and chest) is a waste of water and
an inefficient means of cooling. Drinking water often is the best way to maintain a cool and
functioning body.
Water is scarce above the timberline. After setting up a perimeter (patrol base, assembly area,
defense), a watering party should be employed. After sundown, high mountain areas freeze, and
snow and ice may be available for melting to provide water. In areas where water trickles off
rocks, a shallow reservoir may be dug to collect water (after the sediment settles). Water should
be treated with purification tablets (iodine tablets or calcium hypochlorite), or by boiling at least
one to two minutes. Filtering with commercial water purification pumps can also be conducted.
Solar stills may be erected if time and sunlight conditions permit (FM 3-05.70). Water should be
protected from freezing by storing it next to a Soldier or by placing it in a sleeping bag at night.
Water should be collected at midday when the sun thaw available.

NUTRITION
2-3. Success in mountain operations depends on proper nutrition. Because higher altitudes affect eating
habits, precautions must be taken. If possible, at least one hot meal each day should be eaten, which may
require personnel to heat their individual rations.

ACCLIMATIZATION
2-4. The following elements are characteristic of nutritional acclimatization in mountain operations:

Weight loss during the first two to three days at high elevation.

A loss of appetite with symptoms of mountain sickness.

Loss of weight usually stops with acclimatization.

At progressively higher elevations (greater than 14,000 feet), the tolerance of fatty/high-protein
foods rapidly decreases. A high carbohydrate diet may lessen the symptoms of acute mountain
sickness and is digested better than fat at high altitudes.

FATIGUE
2-5. Increased fatigue may cause Soldiers to become disinterested in eating properly. Decreased
consumption may result in malnutrition because of the unpleasant taste of cold rations. Leaders should
ensure that fuel tablets and squad stoves are available, or that natural flammable materials are used if
possible. Although there is no physiological need for food to be hot, hot food does increase morale and a
sense of well being. Loss of weight in the first few days occurs because of dehydration, metabolic changes,
and loss of appetite. Carbohydrate-containing beverages, such as fruit juices and sports drinks, are an
effective means of increasing carbohydrates, energy, and liquid intake when the normal appetite response is
blunted at altitude.

2-2

TC 3-97.61

26 July 2012

Mountain Living

REQUIRED FOOD COMPONENTS
2-6. Three major food components are required to maintain a well-functioning body: proteins, fats, and
carbohydrates. These food components provide energy, amino acids, vitamins, fiber, and minerals. All
three components must be provided in the correct proportions to maintain a healthy body.

Protein
Mechanism
2-7. Proteins consist of a large number of amino acid units that are linked together to form the protein.
The amino acids, resulting from digestion of protein, are absorbed through the intestine into the blood.
Function
2-8. Proteins are used to make or replace body proteins (muscle and body tissue).
Sources
2-9. Sources of readily usable animal proteins include eggs, milk, cheese, poultry, fish, and meats. Other
foods such as cereals, vegetables, and legumes also provide amino acids, but these proteins are less
balanced in essential amino acid composition than are meat, egg, or milk proteins.
Minimum Daily Requirement
2-10. The minimum requirement, regardless of physical activity, is 8 ounces of protein daily for a
154-pound man. Since amino acids are either oxidized for energy or stored as fats, consuming excess
protein is inefficient.
Effect on Hydration
2-11. Proteins may increase the water intake needed for urea nitrogen excretion. Protein requires water for
digestion and may facilitate dehydration.
Energy Yield
2-12. Proteins provide the body about four kilocalories of energy per gram.
Digestibility
2-13. Proteins require more energy than fats or carbohydrates to digest.

Fats
Function
2-14. Fats are the body’s natural and most concentrated source of stored food energy.
Sources
2-15. Main sources of fats are meats, nuts, butter, eggs, milk, and cheese.
Minimum Daily Requirement
2-16. Of the total daily caloric intake, 25 to 30 percent may be supplied as fats.
Effect on Hydration
2-17. Fats require more water and oxygen to digest than protein.

26 July 2012

TC 3-97.61

2-3

Chapter 2

Energy Yield
2-18. Fats provide the body around 9 kilocalories of energy per gram.
Digestibility
2-19. Fats are easier to digest than protein, but harder to digest than carbohydrates. Fats are harder to digest
at higher altitudes.

Carbohydrates
Mechanism
2-20. In the form of glucose, carbohydrates are found in the most important energy-producing cycles in the
body’s cells. If carbohydrate intake exceeds energy needs, moderate amounts are stored in the muscles and
liver. Larger amounts are converted into fats and stored in that form.
Function
2-21. Carbohydrates are an important source of calories.
Sources
2-22. Nutritionally, the most useful sources of carbohydrates are foods such as unrefined grains,
vegetables, and fruit.
Minimum Daily Requirement
2-23. Carbohydrates should comprise up to 50 percent of the total daily caloric intake.
Energy Yield
2-24. Carbohydrates provide the body around 4 kilocalories of energy per gram.
Digestibility
2-25. Carbohydrates are easier to digest than proteins.

Vitamins
2-26. If an improper and unbalanced diet is likely to occur during a deployment, vitamin supplements
should be considered, especially if this period is to exceed 10 days.
Mechanism and Function
2-27. Vitamins are classified into two groups on the basis of their ability to dissolve in fat or water. The
fat-soluble vitamins include vitamins A, D, E, and K. The water-soluble vitamins include the B vitamins
and vitamin C.
Sources
2-28. Water-soluble vitamins are found in cereals, vegetables, fruits, and meats, but a well-balanced diet
provides all of the required vitamins. Since most water-soluble vitamins are not stored, a proper diet is
necessary to ensure adequate levels of these vitamins.

2-4

TC 3-97.61

26 July 2012

Mountain Living

Minerals
Sources
2-29. Required minerals are contained in a balanced diet (meats, vegetables, fruits).
Minimum Daily Requirement
2-30. Mineral elements can be divided into two groups: those needed in the diet in amounts of 100
milligrams or more a day such as calcium, phosphorous, and magnesium; and trace elements needed in
amounts of only a few milligrams a day such as iodine, iron, and zinc.

BALANCED DIET
2-31. Eating a balanced diet provides the energy needed to conduct daily activities and to maintain the
internal body processes. A balanced diet containing adequate amounts of vitamins and minerals ensures an
efficient metabolism. Since climbing is a strenuous activity and demands high-energy use, a balanced diet
is a necessity.

The efficiency of the body to work above the basal metabolism varies from 20 to 40 percent,
depending on the Soldier. Over 50 percent of caloric intake is released as heat and is not
available when the Soldier works. (About 4,500 calories are expended for strenuous work and
3,500 calories for garrison activity.) Heat is a by-product of exertion. Exertion causes excessive
bodily heat loss through perspiration and increased radiation. During inactivity in cold weather,
the metabolism may not provide enough heat. The “internal thermostat” initiates and causes the
muscles to shiver, thus releasing heat. Shivering also requires energy and burns up to 220
calories per hour (estimate based on a 100-pound person).

With an abrupt ascent to high altitudes, the Soldier experiences physiological acclimatization.
The circulatory system labors to provide the needed oxygen to the body. Large meals require the
digestive system to work harder than usual to assimilate food. Large meals may be accompanied
by indigestion, shortness of breath, cramps, and illness. Therefore, relatively light meals that are
high in carbohydrates are best while acclimatizing at higher elevations. Personnel should eat
moderately and rest before strenuous physical activity. Since fats and protein are harder to
digest, less digestive disturbances may occur if meals are eaten before resting. A diet high in
carbohydrates is not as dense in energy and may require eating more often. Consuming
carbohydrates, beginning in the morning and continuing through mid-afternoon, are important in
maintaining energy levels.

Extra food should be carried in case resupply operations fail. Food should be lightweight and
easy to digest, and be eaten hot or cold. Meals ready to eat (MREs) meet these criteria, and
provide the basic food groups. Commanders may consider supplementing MREs with breakfast
bars, fruits, juices, candies, cereal bars, and chocolate. Bouillon cubes can replace water and salt
as well as warming cold bodies and stimulating the appetite. Hot beverages of soup, juices,
powdered milk, and cider should also be considered. Since coffee, tea, and hot chocolate are
diuretics, the consumption of these beverages should not be relied upon for hydration.

Warm meals should be provided when possible. When cooking, the heat source must be kept
away from equipment and ammunition. At higher elevations, the cooking time may be doubled.
To conserve fuel, stoves, fires, and fuel tablets should be protected from the wind. Extra fuel
should be stored in tightly sealed, marked, metal containers. Use stoves and heat tabs for
warming food and boiling water. Canteen cups and utensils should be cleaned after use. All food
items and garbage are carried with the unit. If possible, garbage should be burned or deep buried.
Caution must be taken to prevent animals from foraging through rucksacks, ahkios, and burial
sites. As all missions are tactical, no trace of a unit should be detected.

Certain drugs, medications, alcohol, and smoking have adverse effects on the circulation,
perspiration, hydration, and judgment of Soldiers. Therefore, they should be avoided when
operating in extremely cold conditions or at high altitudes.

26 July 2012

TC 3-97.61

2-5

Chapter 2

PERSONAL HYGIENE AND SANITATION
2-32. The principles of personal hygiene and sanitation that govern operations on low terrain also apply in
the mountains. Commanders must conduct frequent inspections to ensure that personal habits of hygiene
are not neglected. Standards must be maintained as a deterrent to disease, and as reinforcement to discipline
and morale.

PERSONAL HYGIENE
2-33. This is especially important in the high mountains, mainly during periods of cold weather. In
freezing weather, the Soldier may neglect washing due to the cold temperatures and scarcity of water. This
can result in skin infections and vermin infestation. If bathing is difficult for any extended period, the
Soldier should examine his skin and clean it often. Snow baths in lieu of a water bath are recommended.
This helps reduce skin infections and aids the comfort of the Soldier.

Snow may be used instead of toilet paper. Soldiers should shave at rest periods in the shelter so
that oils stripped in shaving will be replenished. A beard may mask the presence of frostbite or
lice. Water-based creams and lotions should be avoided in cold environments since this will
further dehydrate tissues and induce frostbite by freezing. The nonwater-based creams can be
used for shaving in lieu of soap. Sunscreens and chapsticks should be used on lips, nose, and
eyelids. Topical steroid ointments should be carried for rashes. The teeth must also be cleaned to
avoid diseases of the teeth and gums. Underwear should be changed when possible, but this
should not be considered a substitute for bathing. When operating in areas where resupply is not
possible, each Soldier should carry a complete change of clothing. If laundering of clothing is
difficult, clothes should be shaken and air-dried. Sleeping bags must be regularly cleaned and
aired.

The principles of foot hygiene must be followed to protect the feet from cold injuries. The
causes of such injuries are present throughout the year in high mountains. Boots should be laced
tightly when climbing to provide needed support but not so tight as to constrict circulation.
Socks should be worn with no wrinkles since this causes blisters on the feet. Feet should be
washed daily, and kept as dry and clean as possible. If regular foot washing is impossible, socks
should be changed often (at halts and rest periods or at least once a day) and feet massaged,
dried, and sprinkled with foot powder. Talc or antifungal powder should be used when
massaging; excess powder is brushed off to avoid clumping, which may cause blisters. Feet can
be cleaned with snow, but must be quickly dried. Whenever changing socks, Soldiers should
closely examine their feet for wrinkles, cracks, blisters, and discoloration. Nails should be
trimmed but not too short. Long nails wear out socks; short nails do not provide proper support
for the ends of the toes. Medical attention should be sought for any possible problems.

Feet should be sprayed two or three times a day with an aluminum chlorohydrate antiperspirant
for a week and then once a day for the rest of the winter. If fissures or cracks occur in the feet, it
is best to discontinue spraying until they are healed or to spray less often to control sweating.
This process stops about 70 percent of the sweating in the feet.

During periods of extreme cold, there is a tendency for the Soldier to become constipated. This
condition is brought about by the desire to avoid the inconvenience and discomfort of
defecating. Adequate water intake plus a low protein, high roughage diet can be helpful in
preventing constipation.

SANITATION
2-34. In rocky or frozen ground, digging latrines is usually difficult. If latrines are constructed, they should
be located downwind from the position and buried after use. In tactical situations, the Soldier in a
designated, downwind location away from water sources may dig “cat holes.” Since waste freezes, it can be
covered with snow and ice or pushed down a crevasse. In rocky areas above the timberline, waste may be
covered with stones.

2-6

TC 3-97.61

26 July 2012