What happened
Witnesses observed the pilot approaching the airstrip at a high speed and high altitude. During the final approach, one witness reported that the pilot performed 'S'-turns and side-slipped the aircraft. The unidentified aircraft touched down on the 1950-foot grass runway between the halfway point and three-quarters of the way down the strip. Shortly after touchdown, full power was applied, and the airplane began a steep climb.
As the aircraft approached the end of the runway, it reached an altitude estimated by witnesses to be between 30 and 75 feet above ground level. With full flaps extended, the right wing dropped, causing the airplane to descend at a steep angle into a ravine located approximately 100 feet below the runway elevation.
The investigation
The investigation found no preexisting mechanical deficiencies in the aircraft. Toxicological testing conducted by the FAA on the pilot yielded negative results for ethanol, cyanide, and carbon monoxide. However, tests revealed the presence of bupropion in the pilot's blood and urine. The pilot had been taking Zyban, a prescription medication used for smoking cessation and the treatment of depression and ADHD.
Findings
While the pilot was using buproprion as part of an effort to stop smoking, FAA regulations prohibit medical certification for pilots using this medication unless it has been at least 72 hours since the last dose.