Beech F33 — Hatboro, PA

What happened

The pilot departed just after sunrise on the instrument flight rules flight, which was the first takeoff of a multiday, cross-country trip. According to the National Transportation Safety Board performance study, which used automatic dependent surveillance-broadcast (ADS-B) data, and weather data, the airplane flew the runway heading after departure for about 1 minute and then likely entered the base of an overcast cloud layer, which extended from about 900 ft mean sea level (msl) to about 1,800 ft msl. After the airplane had been in the instrument meteorological conditions for about 20-30 seconds, the airplane banked right and deviated from the runway heading and then banked left, reaching its maximum recorded altitude of 1,186 ft msl. The airplane then began a steep descent at a rate of 2,000 ft/min while gaining airspeed. In the descent, the airplane banked right to about 30° right wing down before coming back to wings level just before the end of the data. The airplane’s final calculated airspeed was 180 kts and last recorded altitude was 586 ft msl, which was less than 1/4 mile from the accident site. A witness located near the accident site saw the airplane flying with the right wing low just before hearing an impact, and two witnesses described the engine as “loud.”

The pilot's communication with air traffic control (ATC) was routine until the pilot communicated in error on the tower frequency while attempting to contact departure control, and he subsequently failed to check in with departure control as instructed. There was no distress call received from the pilot on either radio frequency.

Postaccident examination of the airplane did not reveal any evidence of preimpact mechanical malfunctions that would have precluded normal operation. The wreckage debris path and propeller signatures, in addition to the witness statements, were consistent with the engine producing high power at the time of impact.

The airplane's flight profile after it entered the clouds was consistent with the pilot experiencing spatial disorientation and subsequently losing airplane control. Several factors support this conclusion, which include the weather conditions likely restricting the pilot's visibility and the airplane’s abrupt roll and heading changes, which were followed by a steep accelerating vertical descent and a highly fragmented wreckage and debris path. A change from runway heading was not expected, as ATC had instructed the pilot to maintain runway heading, and the airplane had not reached the initial assigned altitude of 2,000 ft msl; thus, the abrupt changes in climb rate and roll/heading were contrary to ATC instructions. About the time of the roll and heading changes, it is also likely the pilot would have been distracted by his attempt to contact departure control on the correct frequency. It could not be determined why the pilot was unable to regain control after the airplane likely exited the cloud layer on the rapid descent; however, visibility along the route of flight was restricted by haze, mist, and likely sun glare, as the sun had just risen, and several witnesses described the light conditions as bright.

It is likely that the autopilot was not engaged during the accident flight, given the flight instructor’s statement that the pilot usually did not engage the autopilot until cruise flight, coupled with the flight track data and the deviation in heading. In addition, review of the ADS-B data found that none of the likely preset roll, pitch, or airspeed limits of the airplane's flight envelope protection system were exceeded; thus, the protection system likely did not engage if it was turned on.

Review of the pilot's medical records did not suggest a high risk for a sudden incapacitating event. While close family relations were unaware of any recent health problems, a fuel technician recalled that the pilot mentioned having chest pains the day before the accident, it is not clear if the pilot’s comment referred to heart pain or musculoskeletal chest pain. The autopsy of the pilot was limited by extensive injuries; thus, evidence of any acute processes or chronic conditions that would have placed the pilot at an increased risk of a sudden incapacitating event was unavailable, and the toxicology report did not find evidence of any impairing drugs. Given the available medical information, it could not be determined if the pilot had a medical condition that could have contributed to the cause of the accident.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.