A successful recovery operation is done quickly and safely. Care must be exercised when erecting and using equipment to prevent damage to vehicles and equipment and to prevent injury to personnel.
CAUTION: Think Safety. Recovery is a big job. Before any recovery operation, calculate the resistance, inspect tackle, and keep rigging references handy. A haphazard approach to recovery can lead to dismemberment, death, and/or damaged equipment.
Failure occurs when a weight is allowed to fall for a distance and is suddenly stopped. A similar strong force occurs when power is engaged suddenly to recovery vehicles when connected to a towed or mired vehicle. Do not apply loads suddenly (shock load). This puts excessive strain on the equipment, and it may fail
CAUTION: A winch line makes a deadly slingshot. If the dead line of a snatch block breaks, a 200-pound snatch block can travel as far as 300 yards in the air. All personnel observing should stand at least one cable length away from (or the length designated by the recovery vehicle) and opposite of the angle of pull (figure 4-1) when the cable is under stress. This will allow greater reaction time for personnel to move out of the path of flying objects if a cable or other attaching hardware breaks.
Make every effort to stand clear of wire rope that is under tension. The minimum safe distance is twice the length of the payed-out cable. When wire rope is drawn taut and then released suddenly by a break, its recoil (or backlash) may cut a person into two pieces. A winch line under load stretches like a rubber band and stores up tremendous potential kinetic energy. In fact, a steel winch cable weighing 50 to 500 pounds has more spring to it than rubber.
Make sure the rigging lines are not crossing each other before the winching operation is continued. Crossed rigging lines can rub against each other causing damage to the cable or an increased amount of tackle resistance. Crossed cables are only recommended for towing a disabled vehicle when a tow bar is not available.
To safely control a recovery operation, use two ground guides—one ground guide in the front and one in the rear. Only one ground guide gives the signals to the operator. The ground guides should stand apart from other personnel at the recovery site and be in a position where the vehicle operators can easily observe the signals. The vehicle operators must know the meaning of the signals and act only on those signals.
For rigging, position the hook with the open part (throat) upward. If the hook should straighten out from overload, the rigging would be forced downward. If the hook were positioned with the open part (throat) down, the rigging would travel upward unrestricted and possibly cause injury to personnel or damage to vehicles.
Inspect equipment thoroughly before the recovery operation starts. Direct the recovery vehicle operator to apply power to the winch to remove the slack from the rigging, and then stop the operation so the rigging can be inspected without endangering personnel. When inspecting the rigging, never place the hands or body between cables under tension.
Operators and other personnel, in both the recovery and disabled tracked vehicles, must keep their hatches closed during winching and AKERR operations. Operators should use their periscopes to view hand and arm signals.
Safety Keys and Shackle Pins
Safety keys/shackle pins should be in place on all tow hooks, shackles, or other items of equipment. Even though the safety key/shackle pin supports no great load, its absence can allow a pin to move which places excessive force on only a part of a connection. Some shackles use a threaded-type pin. If the pin is not completely inserted into the shackle threads, the shackle or pin can be bent or broken when force is applied.
When using shackle pins with safety keys, such as the type used in tow bars, all shackle pins in a vertical plane should have their heads pointing upward. Should the safety key break or fall out, the shackle pins will remain in position if the load shifts.
Maintain the correct speed when towing vehicles. Consider the terrain, weather, and road conditions when determining speed.
Source: U.S Army FM 4-30.31, Recovery and Battle Damage Assessment and Repair