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Jungle Obstacles

Section I. GENERAL

Units operating in the jungle will have to cross many obstacles. The most difficult obstacles will be streams and cliffs. In addition, units operating in the jungle will frequently have to insert or extract soldiers and units in places where helicopters cannot land. This appendix covers the skills required to perform these tasks.

Before learning these skills, however, soldiers must be familiar with ropes and knots.




Nylon. Nylon rope is most commonly used in climbing and rappelling. The rope is seven-sixteenths of an inch in diameter and is issued in 120-foot lengths. Its dry breaking strength averages 3,840 pounds (plus or minus 5 percent). Strength is reduced by about 20 percent when the rope is wet. It will also stretch about one-third of its length when wet. Nylon sling (utility) ropes are commonly prepared by a unit in 12-foot lengths from older ropes that are no longer used for climbing or rappelling.

Vegetable Fiber. This is readily available in jungle areas as it is made primarily from the fibers of tropical plants.

Manila rope is made from the fibers of the leaves of a banana tree. The lighter the color of the rope, the better the quality. This rope is superior to nylon rope for suspension traverses and rope bridges because it does not stretch as much as nylon, and it is not weakened when wet.



  I. General

 II. Characteristics and Use of Equipment

III. Moving Down Hills and Cliffs

IV. Moving by Helicopter

 V. Moving Across Water Obstacles


The breaking strength and safe load capacity (respectively) for the sizes of manila rope most often used by jungle troops are:

1-inch-diameter rope-9,000 pounds/2,250 pounds

1 /2-inch-diameter rope-3,650 pounds/660 pounds

Hemp rope is made from the fibers of the hemp plant. This is the strongest of the fiber ropes. It is usually soaked in tar to preserve the rope from damage caused by dampness, but this tar tends to reduce the rope's strength. Also, because of its greater weight, tarred hemp is not practical for use by infantry troops.

NOTE: The breaking strength of a rope is always greater than its safe working capacity. The difference is a "safety factor. " Individual ropes can vary greatly in minimum breaking strength. Even though a rope may not break under this load, the fibers are stretched beyond their elastic limit. Thereafter the strength of the rope is permanently reduced. Exposure, wear, use, and bending decrease a rope's strength over a period of time. This should be allowed for in estimating the strength of a used rope. The strength of a rope that is slung over a hook or contains a knot is reduced by about 30 percent; sharp bends over corners will cut strength by 50 percent; sand or grit between the fibers will quickly cut the fibers, and sharply drop the overall strength of the rope.


Clean a muddy rope by washing it in water, but not in salt water.

Do not pull a rope over sharp edges. Place layers of heavy cloth or grass between the rope and any sharp edge to prevent the cutting of fibers.

Do not drag a rope through sand and dirt, or step on it, or drive over it.

Keep a rope dry. If it gets wet, dry it as soon as possible to prevent rotting. (A mildewed rope will have a musty odor and inner fibers will have a dark, stained look.)

Do not leave a rope knotted or tightly stretched any longer than needed.

Never splice a climbing or rappelling rope.

Inspect a rope often, both the outside and the inside. Untwist a few strands at different points to open the rope to check the inside.

Melted nylon and dark streaks indicate burns. Nylon rope burns when it rubs against other nylon ropes. Nylon ropes should never be tied in such away that there is rope-to-rope friction.

Dirt and sawdust-like material inside the rope indicates damage.

A rope should be checked at a number of different places--any weak point in it weakens the entire rope.

Whenever any unsafe conditions are found in a rope, it should be destroyed or cut up in short pieces. This w-ill prevent use of the rope for hoisting. The short pieces can be used for toggle ropes and for other purposes which do not involve load bearing operations.



Rappelling is a means to move quickly down very steep hills and cliffs. Rappelling involves sliding down a rope which has been anchored around a firm object (anchor point) such as a tree, projecting rock, or piton.




The hasty rappel is a fast, easy way to get down a moderately steep slope or cliff. A soldier must wear a shirt to do a hasty rappel.


The seat-hip rappel is a fast method of getting down a steep hill or cliff, and it is also used to rappel from helicopters. In this rappel, friction is taken up by a snaplink inserted in a rappel seat fastened to the body.


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In the jungle, there are many places where the vegetation or the ruggedness of the terrain will not permit a helicopter to land. Therefore, it maybe necessary to rappel from a helicopter to get on the ground. Special equipment is required to rappel from helicopters. There are no safe field expedients. The following paragraphs describe the equipment and procedure used in rappelling from helicopters and furnish information on other extraction means.


The donut ring is the primary anchoring device (anchor point) inside a helicopter. The floating safety ring is the secondary anchor point. The donut ring consists of a 12-inch solid ring of 1/2-inch cold-rolled steel cable; seven parachute static line snap hooks; four 1/2-inch U-bolts; and 12 inches of chain or 1/8-inch cable. Instructions for making a donut ring and a floating safety ring are found in FM 57-38.

The log coil helps the double rappelling rope fall clear of the aircraft. To prepare it, start with the running end of the rope and coil the rope evenly and tightly around the log. Use a log approximately 2 to 3 inches in diameter and 16 to 24 inches long.

A system that has proven to be almost ideal for rope deployment in helicopter rappel operations is that of the rope deployment bag. The rope deployment bag is issue as a component of the Stabo extraction system The ropes are prepared in the normal rappel configuration and stretched to full length The D-bag is placed at the loose ends of rope opposite the snaplinks. After insuring that all rubber bands are present all stowing lines of the D-bag, a bight is formed in the two runnings ends of the rappel ropes and then placed in the center retainer band just above the stow pocket. The rope is then folded and stowed in the retainer bands working from side to side of the D-bag, while making sure that folds do not extend past either side of the D-bag. Six to eight folds of rope are placed in each retainer band, working towards the top of the D-bag. Once the top of the bag is reached, a bight is formed in the climbing ropes 24 inches below the first snaplink and stowed in the top center retainer band. After the D-bag is inspected, the bag is rolled, going from bottom to top, leaving the snaplinks exposed. Tape is used to secure the top flap of the bag.


The rappelling rope is connected to the donut ring and the floating safety ring, in the following order, and in the manner described.

To rappel from a helicopter.

  • Hook into the rope, as in the seat-hip rappel, upon entering the helicopter. Sit on the floor, keeping the brake hand firmly in the small of the back.
  • Place the rope in lap.
  • Upon the command, "GET READY," look toward the donut ring and pull on the rope to check the anchor point connection. Check the rappel seat and snaplink to insure that the rope is properly inserted. Conduct a final visual inspection of the hookup.
  • Upon the command, "SIT IN THE DOOR," swing the feet out to the helicopter skid, keeping the brake on.
  • Upon the command, "DROP ROPE," drop the rope with the guide hand, insuring that the rope does not fall between the cargo compartment and the skid and that the rope is not tangled or fouled.
  • Upon the command, "POSITION," using the guide hand to assist, pivot 180 degrees on the helicopter and skid bar. Face the inside of the helicopter. Spread the feet shoulder-width apart; lock the knees; and bend forward at the waist, forming an "L" body position.
  • Upon the command, "Go," flex the knees and jump backward, letting the rope run through both the brake hand and the guide hand. Descend 5 to 10 meters at a time, looking at the ground over the brake hand. Keep the feet together and legs straight, while maintaining the "L" body position.
  • Upon reaching the ground, back all the way out of the rope and move quickly away from beneath the helicopter.


The troop ladder is a good method for larger groups to enter or leave an area where the helicopter cannot land. Installation of the ladder is an aviation responsibility. The crew chief will control the number of troops on the ladder. Only five or six troops will be allowed on the ladder at a time.

Use the legs for climbing and descending; the arms for stability and holding the ladder close to the body.

If possible, each soldier, and especially those carrying heavy loads, should tie a rappel seat with a snaplink attached before ascending. Then, if he becomes tired, he can "snap in," avoiding the chance of a fall.

When going down a ladder, the first soldier on the ground steadies the ladder for the remaining troops. When climbing up a ladder, the soldier designated to hold the ladder steady is the last one up the ladder. If the helicopter starts going up before everyone is loaded, the soldier holding the ladder on the ground should release it at once.

When on the ladder, remain calm at all times. If the helicopter should start settling to the ground, stay calm, watch the ground, and stay on the ladder until reaching the ground.

Once on the ground, move from underneath the helicopter.

The jungle penetrator is a metal seat rescue assembly attached to a winch on a helicopter. The seats remain folded when the device is being lowered. The seats are unfolded when the device is on the ground. A conical nose allows it to penetrate the jungle foliage. One to three soldiers (two is a standard load) can be placed on it. Nylon straps are placed under the arms of the soldier(s) to be hoisted. The device lifts the soldier(s) into the helicopter.




Other means which can be used for extraction of troops where landing zones (LZ) are not available include such devices as the personnel Stabo extraction system, the Maguire rig, the Palmer rig, or the jungle operations extraction system (JOES).


This system provides a means for rapid pickup of soldiers by helicopter from areas where the helicopter cannot land. The system consists of the personnel harness, the bridle, the suspension rope, the safety rope, and the deployment bag.

As the pickup process is initiated, the helicopter hovers over the pickup zone at altitudes up to 150 feet. A member of the helicopter crew drops the extraction system deployment bag from the left door of the helicopter. (A maximum of three units may be connected and dropped simultaneously.) As the deployment bag descends, the suspension rope deploys until the bag reaches the ground. The soldier to be extracted then attaches the bridle snaphooks to the lift V-rings on his harness. After insuring that the leg straps are connected and tight the soldier notifies the helicopter by radio or hand signals that liftoff may begin. The helicopter then lifts the soldier from the area and, carrying him suspended beneath the helicopter, moves to an area where a safe landing can be made. The helicopter then lowers the suspended soldier to the ground, lands nearby, and allows him to board the helicopter. For details on employing this system, consult TM 10-1670-262-12.


This rig is constructed with the 120-foot nylon rope and two 12-foot nylon sling ropes. One end of the 120-foot rope is secured to the donut ring. The running end of the 120-foot rope is tied with an end of the rope bowline knot at the end of the rope. One of the 12-foot sling ropes is tied 3 feet above the bowline with a Prusik knot, and the loose ends are tied off with a square knot to form a loop. The rider uses the remaining sling rope to form a rappel seat. He then fastens a snaplink to the rappel seat and the bowline knot; places his arms up and through the upper loop; and is extracted. The Palmer rig is relatively safe and may be used when evacuating wounded personnel.


This rig is also simple and easy to construct. It is made with an 8-foot by 2-inch piece of nylon webbing sewn together at the ends to form a loop containing a D-ring. A smaller slip loop (wrist loop) is sewn 12 inches down from the top of the larger loop. During extraction, the rider simply sits in the seat of the large loop. He then places his wrist in the slip loop and tightens the loop, insuring that he does not fall from the larger loop during extraction.


This system was developed after careful evaluation of the three previously mentioned systems, while considering those items of equipment available to the individual soldier. The JOES can be quickly constructed from components readily available from the supply system. The individual soldier requires very little (10 to 15 minutes) training in what he will be required to do if he needs to be extracted, and only a maximum of 5 minutes is required for him to actually prepare for extraction.

Each individual who is to be extracted must have a 12-foot utility rope and a snaplink. If the individual does not have these items, they can be dropped to him with the JOES. The individual to be extracted makes a rappel seat out of the 12-foot utility rope and installs the snaplink as if he were going to make a rappel.

When JOES is dropped, he and his buddy move to the bag. Each individual hooks his snaplink into one loop at the end of the rope bowline, and places the loop formed by one of the 12-foot utility ropes over his shoulders and under his armpits. He and his buddy stay as far back from the helicopter as practical until it starts to lift up, and as tension is put on the rope, they move forward until they are directly underneath it and linked up with other personnel. All soldiers should link up by holding onto the adjacent person's equipment.



There are several expedient ways to cross rivers and streams. The ways used in any situation depends on the width and depth of the water, the speed of the current, the time and equipment available, and the friendly and enemy situation.

There is always a possibility of equipment failure. For this reason, every soldier should be able to swim. In all water crossings several strong swimmers should be stationed either at the water's edge or, if possible, in midstream to help anyone who gets into trouble.

If a soldier accidentally falls into the water, he should swim with the current to the nearer bank. Swimming against the current is dangerous because the swimmer is quickly exhausted by the force of the current.


A good site to ford a stream has these characteristics:

  • Good concealment on both banks.
  • Few large rocks in the river bed. (Submerged large rocks are usually slippery and make it difficult to maintain footing.)
  • Shallow water or a sandbar in the middle of the stream. Troops may rest or regain their footing on these sandbars.
  • Low banks to make entry and exit easier. High banks normally mean deep water. Deep water near the far shore is especially dangerous as the soldiers may be tired and less able to get out.

A unit should cross at an angle against the current. Each soldier should keep his feet wide apart and drag his legs through the water, not lift them, so that the current will not throw him off balance. Poles can be used to probe in front of the troops to help find deep holes and maintain footing.


For deeper streams which have little current, soldiers can use a number of floating aids such as the following:

  • The standard air mattress
  • Trousers

NOTE: Trousers must be soaked in water before using.

  • Canteen safety belt
  • Poncho life belt
  • Water wings
  • Poncho brush raft
  • Australian poncho raft
  • Log rafts

When launching any poncho raft or leaving the water with it, take care not to drag it on the ground as this will cause punctures or tears.


For crossing streams and small rivers quickly, rope bridges offer a suitable temporary system, especially when there is a strong current. Because of the stretch factor of nylon ropes, they should not be used to cross gaps of more than 20 meters. For larger gaps, manila rope should be used.

In order to erect a rope bridge, the first thing to be done is to get one end of the rope across the stream. This task can be frustrating when there is a strong current. To get the rope across, anchor one end of a rope that is at least double the width of the stream at point A. Take the other end of the line upstream as far as it will go. Then, tie a sling rope around the waist of a strong swimmer and, using a snaplink, attach the line to him. He should swim diagonally downstream to the far bank, pulling the rope across.

One-Rope Bridge. A one-rope bridge can be constructed either above water level or at water level. The leader must decide which to construct. The bridge is constructed the same regardless of the level.

Crossing Method above Water Level. Use one of the following methods.

Commando crawl. Lie on the top of the rope with the instep of the right foot hooked on the rope. Let the left leg hang to maintain balance. Pull across with the hands and arms, at the same time pushing on the rope with the right foot. (For safety, each soldier ties a rappel seat and hooks the snaplink to the rope bridge.)

Monkey crawl. Hang suspended below the rope, holding the rope with the hands and crossing the knees over the top of the rope. Pull with the hands and push with the legs. (For safety, each soldier ties a rappel seat and hooks the snaplink to the rope bridge.) This is the safest and the best way to cross the one-rope bridge.

Crossing Method at Water Level. Hold onto the rope with both hands, face upstream, and walk into the water. Cross the bridge by sliding and pulling the hands along the rope. (For safety, each soldier ties a sling rope around his waist, leaving a working end of about 3 to 4 feet. He ties a bowline in the working end and attaches a snaplink to the loop. He then hooks the snaplink to the rope bridge.)

To recover the rope, the last soldier unties the rope, ties it around his waist and, after all slack is taken up, is pulled across.

Two-rope bridge. Construction of this bridge is similar to that of the one-rope bridge, except two ropes, a hand rope and a foot rope, are used. These ropes are spaced about 1.5 meters apart vertically at the anchor points. (For added safety, make snaplink attachments to the hand and foot ropes from a rope tied around the waist. Move across the bridge using the snaplink to allow the safety rope to slide.) To keep the ropes a uniform distance apart as men cross, spreader ropes should be tied between the two ropes every 15 feet. A sling rope is used and tied to each bridge rope with a round turn and two half-hitches.


Suspension traverses, bridges, and cableways can be used to move large numbers of soldiers or heavy equipment over wide rivers and ravines, or up and down cliffs in a short period of time. Because heavy or bulky material or equipment is needed to construct these expedients, their use is practical only if the needed items can be transported to the site by air or surface means (watercraft, pack animals, etc.).

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