Martinaire

The single engine airplane departed Houston-George Bush-Intercontinental Airport at 0910LT on a cargo service to Victoria. Twelve minutes later, while climbing to an altitude of 4,200 feet, the aircraft collided with a paraglider. Out of control, it entered a dive and crashed three minutes later in a field. The aircraft was totally destroyed and the pilot, sole on board was killed, as well as the paraglider.

The airline transport pilot departed on a night cargo flight into conditions that included an overcast cloud ceiling and “hazy” visibility, as reported by another pilot. About one minute after takeoff, the pilot made a series of course changes and large altitude and airspeed deviations. Following several queries from the air traffic controller concerning the airplane’s erratic flight path, the pilot responded that he had “some instrument problems.” The pilot attempted to return to land at the departure airport, but the airplane impacted terrain after entering a near-vertical dive. The airplane was one of two in the operator’s fleet equipped with an inverter system that electrically powered the pilot’s (left side) flight instruments. Examination of the annunciator panel lighting filaments revealed that the inverter system was not powered when the airplane impacted the ground. Without electrical power from an inverter, the pilot’s side attitude indicator and horizontal situation indicator (HSI) would have been inoperative and warning flags would have been displayed over the respective instruments. The pilot had a history of poor procedural knowledge and weak flying skills. It is possible that he either failed to turn on an inverter during ground operations and did not respond to the accompanying warning flags, or he did not switch to the other inverter in the event that an inverter failed inflight. Due to impact damage, the operational status of the two inverters installed in the airplane could not be confirmed. However, the vacuum-powered flight instruments on the copilot’s (right side) were operational, and the pilot could have referenced these instruments to maintain orientation. Based on the available information, the pilot likely lost control of the airplane after experiencing spatial disorientation. The night marginal visual flight rules conditions and instrumentation problems would have been conducive to the development of spatial disorientation, and the airplane’s extensive fragmentation indicative of a high-energy impact was consistent with the known effects of spatial disorientation. Ethanol identified during toxicology testing may have come from postmortem production and based on the low levels recorded, was unlikely to have contributed to this accident. Morphine identified in the pilot’s liver could not be used to extrapolate to antemortem blood levels; therefore, whether or to what extent the pilot’s use of morphine contributed to the accident could not be determined.

The pilot landed at the airport to refuel the airplane and pick up cargo. The pilot spoke with three employees of the fixed base operator who stated that he seemed alert and awake but wanted to make a "quick turn." After the airplane was fueled and the cargo was loaded, the pilot departed; the airplane crashed 1 minute later. Night visual meteorological conditions prevailed at the time. An aircraft performance GPS and simulation study indicated that the airplane entered a right bank almost immediately after takeoff and then made a 42 degree right turn and that it was accelerating throughout the flight, from about 75 knots groundspeed shortly after liftoff to about 145 knots groundspeed at impact. The airplane was climbing about 500 to 700 feet per minute to a peak altitude of about 260 feet above the ground before descending. The simulation showed a gas generator speed of about 93 percent throughout the flight. The study indicated that the load factor vectors, which were the forces felt by the pilot, could have produced a somatogravic illusion of a climb, even while the airplane was descending. The postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Based on the findings from the aircraft performance GPS and simulation study, the degraded visual reference conditions present about the time of the accident, and the forces felt by the pilot, it is likely that he experienced spatial disorientation, which led to his inadvertent controlled descent into terrain.