Chapter 17: Emergency Procedures
Emergency Landings
A forced landing is an immediate landing, on or off an airport, due to the aircraft's inability to maintain flight. This would be caused by engine failure, fuel exhaustion/starvation, or any other situation that would require the aircraft to descend.
A precautionary landing is a premeditated landing, on or off an airport, when further flight is possible but inadvisable. This would be caused by deteriorating weather, fuel shortage, or gradually developing engine trouble, or any other factor that would warrant the conclusion of flight. Being lost also might lead to a precautionary landing.
Ditching is a forced or precautionary landing on water.
Psychological Hazards
Pilots can pilot engage in wishful thinking instead of reason, especially when dealing with a self-inflicted predicament. Because of this, many situations calling for a precautionary landing are allowed to develop into an immediate forced landing. Pilots may also be reluctant to accept the emergency situation, delaying critical decisions that must be made to ensure a safe landing.
In an emergency, pilots may feel a strong desire to "save the airplane" with no regard to the risks involved. This can be caused by the pilot's financial stake in the airplane. It also can be caused by the mistaken belief that injury or death will be avoided only if the airplane remains undamaged. However, people often will walk away from forced landings where the airplane is substantially damaged. Pilots should be prepared to sacrifice the airplane for the safety of those on board.
Panic, which can be caused by the undue concern about getting hurt, is a substantial psychological hazard in an emergency scenario. Composed pilots who know how to apply general emergency concepts and procedures have high survival rates. An old aviation saying reminds us that, in an emergency, "you will not rise to the occasion. You will sink to the level of your training."
Basic Safety Concepts
Avoidance of crash injuries is largely a matter of:
- Keeping the cabin area relatively intact by using the wings, landing gear, and fuselage to absorb the violence of rapid deceleration;
- Avoiding forceful bodily contact with interior structure.
The extent of crushable structure between the occupants and the principal point of impact on the airplane has a direct bearing on the severity of the transmitted crash forces, and therefore on survivability.
Avoiding forcible contact with interior structure is a matter of seat and body security. The intact cabin area only has value if the occupants decelerate at the same rate as the structure.
In addition to dispensable airplane structure, vegetation, trees, and even manmade structures may be used to absorb energy. Cultivated fields with dense crops are as effective as emergency arresting device on a runway. Brush and small trees provide cushioning and braking without destroying the airplane.
Groundspeed and stopping distance determine the severity of a deceleration. Doubling groundspeed will quadruple total destructive energy. Touchdown during an emergency landing should be made at the lowest possible controllable airspeed.
While pilots may look for the largest available flat and open field for an emergency landing, very little stopping distance is required if the deceleration forces are spread evenly over the available distance.
The typical light airplane is designed to provide protection in crash landings that expose the occupants to nine times the acceleration of gravity (9G) in a forward direction.
Assuming a uniform 9G deceleration, at 50 mph the required stopping distance is about 9.4 feet. While at 100 mph, the stopping distance is about 37.6 feet, which is about four times greater.
Terrain Selection and Airplane Configuration
If beyond gliding distance of a suitable open area, in an emergency the pilot should judge the available terrain for its energy-absorbing capability. A well-executed crash landing in poor terrain can be less hazardous than an uncontrolled touchdown on an established field.
Premature use of flaps, and the resulting dissipation of altitude, may jeopardize an otherwise sound emergency approach to landing. Use of flaps on final approach is recommended when time and circumstances permit.
Deactivation of the airplane's electrical system before touchdown reduces the likelihood of a post-crash fire. However, the battery master switch should not be turned off until the pilot no longer has any need for electrical power to operate vital airplane systems, such as electric flaps, the radio, and the transponder.
While the pilot should attempt to exploit any power available from a rough-running engine, it is generally better to switch the engine and fuel off just before touchdown. This will emphasize the pilot's initiative over the situation. A cooled-down engine also reduces the risk of post-crash fire.
During an emergency, the final approach should be selected based on wind direction and velocity, the dimensions and slope of the chosen field, and any obstacles in the final approach path.
Rather than landing into the wind over obstacles, it is sometimes better to plan the approach over an unobstructed area, regardless of wind direction. Collision with obstacles at the end of a ground roll or slide is much less hazardous than striking an obstacle at flying speed before the touchdown point is reached.
Terrain Types
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Commercial Pilot & Flight Instructor Test Questions
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