Accident investigations reveal that, as a related factor, weather continues to be cited more frequently than any other in general aviation accidents. The data also show that weather involved accidents are more likely to result in fatal injury than are accidents not involving weather. Low ceilings, rain, and fog continue to head the list in the fatal, weather involved general aviation accidents. The pilot involvement in this type of accident is usually the result of inadequate preflight preparation and/or planning, continued VFR flight into adverse weather conditions, and attempted operation beyond the pilot's experience/ability level. In far too many cases it was determined that the pilot did not obtain a preflight weather briefing. It appears logical, then, to assume that if an adequate preflight briefing had been obtained, unexpected weather conditions would not have been encountered and many of the accidents would not have occurred.

   The only way a pilot can control an airplane safely in a low visibility environment is by using and trusting flight instruments. Man's orientation senses are not designed to cope with flight when external visual references are obscured by clouds, fog, haze, dust, darkness or other phenomena, unless visual reference is transferred to the flight instruments. When the visual sense is provided with reference points such as the earth's horizon or the flight instruments, there is usually no problem with airplane attitude control since the visual sense overrides the other senses.

   It is in situations where visual references such as the ground and horizon are obscured that trouble develops, especially for pilots who lack training, experience, and proficiency in instrument flight. The vestibular sense (motion sensing by the inner ear) in particular tends to confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in the attitude of the airplane, nor can they accurately sense attitude changes which occur at a uniform rate over a period of time. On the other hand, false sensations often are generated, leading the pilot to believe the attitude of the airplane has changed when, in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation (vertigo).

   When a disoriented pilot actually does make a recovery from a turn, bank, climb, or descent, there is a very strong tendency to feel that the airplane has entered a turn, bank, climb, or descent in the opposite direction. These false sensations may lead to the well known "graveyard spiral."

   All pilots should be aware of these illusions and their consequences. Flight instructors should provide each student with an opportunity to experience these sensations under controlled conditions.

   All pilots should be somewhat conservative in judging their own capabilities and should use every means available (weather check, postponed flight, 180 degree turn around, precautionary landing at an airport, etc.) to avoid weather situations which overtax one's ability.

   If inadvertently caught in poor weather conditions, the VFR pilot should, in addition to maintaining control of the airplane, immediately notify the nearest FAA facility by radio, and follow their instructions. Calmness, patience, and compliance with those instructions represent the best chance for survival.

   The use of an airplane equipped with flight instruments and an easy means of simulating instrument flight conditions, such as windshield "slats" or an extended visor cap or hood, are needed for training in flight by reference to instruments.
   Instruction in attitude control by reference to instruments should be conducted with the use of all available instruments in the airplane concerned. When an attitude indicator is provided, its use as the primary reference for the control of the attitude of the airplane should be emphasized.

   The following discussion of maneuvering the airplane by reference to flight instruments is primarily for student pilots and private pilots who have not received the benefit of integrated flight instruction described briefly in the chapter on Basic Flight Maneuvers.

   From the beginning of instruction in maneuvering the airplane by reference to instruments, three important actions should be stressed. First, a person cannot feel control pressure changes with a tight grip on the controls. Relaxing and learning to "control with the eyes and the brain" instead of only the muscles, usually takes considerable conscious effort.

   Second, attitude changes should be smooth and small, yet with positive pressure. No attitude changes should be made unless the instruments show a need for change.

   Third, with the airplane properly trimmed, all control pressure should be released momentarily when one becomes aware of tenseness. The airplane is inherently stable and, except in turbulent air, will maintain approximate straight and level flight if left alone.

   It must be reemphasized that the following procedures are intended only as emergency means for extracting one's self from a hazardous situation once it has been encountered. The main goal is not precision instrument flying; rather, it is to help the VFR pilot keep the airplane under adequate control until suitable visual references are regained.