This section contains information on emergency landing techniques in WSC aircraft. The guidelines that are presented apply to the more adverse terrain conditions for which no practical training is possible. The objective is to instill in the pilot the knowledge that almost any terrain can be considered suitable for a survivable crash landing if the pilot knows how to slow and secure the WSC aircraft while using the WSC structure for protection of the pilot and passenger.
Types of Emergency Landings
The different types of emergency landings are:
- Forced landing—an immediate landing, on or off an airport, necessitated by the inability to continue further flight. A typical example is an aircraft forced down by engine failure.
- Precautionary landing—a premeditated landing, on or off an airport, when further flight is possible but inadvisable. Examples of conditions that may call for a precautionary landing include deteriorating weather, being lost, fuel shortage, and gradually developing engine trouble.
- Ditching—a forced landing on water.
A precautionary landing is less hazardous than a forced landing because the pilot has more time for terrain selection and approach planning. In addition, the pilot can use power to compensate for errors in judgment or technique. The pilot should be aware that too many situations calling for a precautionary landing are allowed to develop into immediate forced landings when the pilot uses wishful thinking instead of reason, especially when dealing with a self-inflicted predicament. Trapped by weather or facing fuel exhaustion, the pilot who does not give any thought to the feasibility of a precautionary landing accepts an extremely hazardous alternative.
Psychological Hazards
There are several factors that may interfere with a pilot’s ability to act promptly and properly when faced with an emergency. These factors include reluctance to accept the emergency situation, the desire to save the aircraft, and undue concern about getting hurt.
A pilot who allows the mind to become paralyzed at the thought that the aircraft will be on the ground in a very short time, regardless of the pilot’s actions or hopes, is severely handicapped. An unconscious desire to delay the dreaded moment may lead to such errors as a delay in the selection of the most suitable landing area within reach and indecision in general. Desperate attempts to correct whatever went wrong at the expense of aircraft control fall into the same category.
The pilot who has been conditioned during training to expect to find a relatively safe landing area whenever the flight instructor closes the throttle for a simulated forced landing may ignore all basic rules of airmanship to avoid a touchdown in terrain where aircraft damage is unavoidable. Typical consequences are making a 180° turn back to the runway when available altitude is insufficient, stretching the glide without regard for minimum control speed in order to reach a more appealing field, or accepting an approach and touchdown situation that leaves no margin for error. The desire to save the aircraft, regardless of the risks involved, may be influenced by two other factors: the pilot’s financial stake in the aircraft and the certainty that an undamaged aircraft implies no bodily harm. There are times, however, when a pilot should be more interested in sacrificing the aircraft so that the occupants can safely walk away from it.
Fear is a vital part of the self-preservation mechanism. However, when fear leads to panic, we invite that which we want most to avoid. The survival records favor pilots who maintain their composure and know how to apply the general concepts and procedures that have been developed through the years. The success of an emergency landing is as much a matter of the mind as of skills.
Basic Safety Concepts
A pilot who is faced with an emergency landing in terrain that makes extensive aircraft damage inevitable should keep in mind that the avoidance of crash injuries is largely a matter of:
- Keeping vital structure (flight deck where the pilot and passenger are seated) relatively intact by using dispensable structure, such as wings, landing gear, and carriage bottom to absorb the violence of the stopping process before it affects the occupants.
- Avoiding forward wing movement relative to the carriage, allowing the mast to rotate into the flight deck occupants, or the front tube to compress and break, providing structure to impale/stab the occupants.
The advantage of sacrificing dispensable structure is demonstrated daily on the highways. A head-on car impact against a tree at 20 miles per hour (mph) is less hazardous for a properly restrained driver than a similar impact against the driver’s door. Statistics indicate that the extent of crushable structure between the occupants and the principal point of impact on the aircraft has a direct bearing on the severity of the transmitted crash forces and, therefore, on survivability. Compared to an airplane, the WSC aircraft has less structure to absorb the impact and is moving slower, but the same principles apply.
Avoiding forcible contact with the front tube, cowling, dashboard, or outside structure is a matter of seat and body security with the use of seatbelts. Unless the occupant decelerates at the same rate as the surrounding structure, no benefit is realized from its relative intactness. The occupant is brought to a stop violently in the form of a secondary collision.
Dispensable aircraft structure is not the only available energy-absorbing medium in an emergency situation. Vegetation, trees, and even manmade structures may be used for this purpose. Cultivated fields with dense crops, such as mature corn and grain, are almost as effective in bringing an aircraft to a stop with repairable damage as an emergency arresting device on a runway. [Figure 13-2]
Brush and small trees provide considerable cushioning and braking effect without destroying the aircraft. When dealing with natural and man-made obstacles with greater strength than the dispensable aircraft structure, the pilot must plan the touchdown in such a manner that only nonessential structure is “used up” in the principal slowing down process.
It should be noted that examples presented here are not to be practiced because these situations are hazardous and can damage the WSC and injure occupants. These examples are shown for informational purposes, in case similar situations arise in the future.
The overall severity of a deceleration process is governed by speed (groundspeed) and stopping distance. The most critical of these is speed; doubling the groundspeed quadruples the total destructive energy and vice versa. Even a small change in groundspeed at touchdown, resulting from wind or pilot technique, affects the outcome of a controlled crash. It is important that the actual touchdown during an emergency landing be made at the lowest possible controllable airspeed using all available means.
Most pilots instinctively—and correctly—look for the largest available flat and open field for an emergency landing. Actually, very little stopping distance is required if the speed can be dissipated uniformly; that is, if the deceleration forces can be spread evenly over the available distance. This concept is designed into the arresting gear on aircraft carriers, and provides a nearly constant stopping force from the moment of hookup.
For example, assuming a uniform 2 G deceleration while landing into a headwind with a 25 mph groundspeed, the stopping distance is about 10.5 feet; in a downwind landing at 50 mph groundspeed, the required stopping distance is 42 feet—about four times as great. [Figure 13-3]
Although these figures are based on an ideal deceleration process, it is interesting to note what can be accomplished in an effectively used short stopping distance. Additionally, landing uphill reduces the stopping distance and landing downhill increases the stopping distance. Understanding the need for a firm but uniform deceleration process in very poor terrain enables the pilot to select touchdown conditions that spread the breakup of dispensable structure over a short distance, thereby reducing the peak deceleration of the flight deck area. A careful consideration must be made considering wind, slope, and terrain.