Cessna 172 N737VC

The pilots onboard the accident airplane took off under visual flight rules at night, and after about 8 minutes, turned toward an undeveloped wetland area where there was little to no ground lighting. About that time, the right-seat pilot sent a text message along with a photograph describing how dark it was outside. As the airplane continued flying, ADS-B data showed that its altitude varied between 1,600 and 1,000 ft before it began to descend at a rate of about 1,700 ft per minute; at the last ADS-B observed position, the descent rate had increased to 3,400 ft per minute. The airplane impacted the swampy area below about 1,000 ft beyond that last track data point. A postaccident examination of the wreckage found no evidence of any preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation. It could not be definitively determined which pilot was flying the airplane; however, it is likely that the left-seat pilot, who had rented the airplane, was flying with the right-seat pilot monitoring (based on statements from the operator). The investigation was also unable to determine the night or instrument currency of either the left- or right-seat pilot, as no logbooks were found for the left-seat pilot and the last non-draft electronic logbook entry for the right-seat pilot was from a year before the accident. Postmortem toxicological testing of samples from the left-seat pilot performed by the local medical examiner detected methamphetamine in blood and urine, whereas testing by the FAA Forensic Sciences Laboratory did not detect methamphetamine in blood, urine, or liver tissue. Neither laboratory detected the methamphetamine metabolite amphetamine. Even if only the peripheral blood methamphetamine level measured by one laboratory was considered, that level would not be indicative of whether methamphetamine was used medicinally or recreationally, nor would that level indicate specific associated effects, which might range from improved reaction time and decreased fatigue to increased risk-tolerance and psychomotor impairment. Some conditions that might be treated with methamphetamine also are potentially impairing, but the reviewed FAA medical certification and death investigation information for the left-seat pilot did not document any such condition. Overall, the left-seat pilot’s postmortem toxicological results were unclear as to his potential impairment. The low level of ethanol detected in the right-seat pilot’s blood, and the fact that ethanol was not detected in vitreous fluid or urine, indicated that some or all of the small amount of detected ethanol may have been from postmortem sources, and that the right-seat pilot was unlikely to have been impaired by ethanol effects at the time of the accident. The circumstances of this accident were consistent with the pilots experiencing spatial disorientation, most likely somatogravic illusion. An aircraft performance study found the apparent pitch angle (or the angle that would be “felt” by the pilots’ vestibular systems) remained nearly nose-level during the initial 20-seconds of the final descent. The night lighting conditions, and particularly the limited cultural lighting along the flightpath, would have made it difficult for the pilots to recognize that the airplane was descending if they were trying to utilize outside visual references to fly the airplane. By the time the pilots may have realized the airplane was descending, it would likely have been at an altitude too low for recovery.

Quoted verbatim from the NTSB record.