Amateur-built S90 N176PA accident near Fresno, California

Probable cause

The pilot's abnormally steep takeoff climb followed by a loss of control and rapid descent to ground impact, for undetermined reasons.

NTSB analysis

The private pilot began flight training in 1996 and had accrued about 187 total hours of flight experience by 2012, mostly in low-performance Cessna and Piper airplanes. The pilot then ceased flying until mid-2016, when he purchased the previously-owned experimental amateur-built, high-performance accident airplane.

In late 2016, when he had accrued about 31 hours of flight experience in the airplane, the pilot and a non-pilot rated passenger departed for a local personal flight. Weather conditions were benign, with light winds, clear skies, and moderate temperature. According to multiple witnesses, some of whom were pilots, the airplane entered a steep climb at some point after it lifted off. The airplane then began a sharp right turn while continuing to climb rapidly. Shortly thereafter, the airplane entered a steep descent and impacted marshy terrain about 900 ft to the northeast of the departure end of the runway.

A flight path reconstructed from data recovered from an onboard GPS device indicated a trajectory that was similar to that indicated by the witness accounts. GPS-derived comparison of the profile of the accident takeoff with those of seven of the pilot's other takeoffs in the airplane from the accident airport revealed that five of the other seven takeoff profiles were similar to one another, and that the accident takeoff profile was markedly different from those five. During the accident takeoff, the airplane remained on or near the ground about 25 seconds longer than it did during those five other takeoffs, and then climbed at a rate that was about twice the rates of those five takeoffs. The other two takeoffs exhibited ground or near-ground travel durations of about 40 seconds, with climb rates similar to those of the other five takeoffs.

Postaccident examination of the engine and airframe did not reveal evidence of any pre-impact mechanical deficiencies or failures that would have precluded normal operation, and the damage was consistent with the engine developing at least moderate power at impact. The airplane was equipped with dual flight controls, but the investigation was unable to determine who was manipulating the controls for the takeoff and flight. The relative sizes of the two occupants were not consistent with the passenger being able to overpower the pilot on the flight controls. The takeoff profile was consistent with an aggressive, more exciting technique sometimes referred to as a "high-performance" or "zoom climb" takeoff. The investigation was unable to determine the reason for this takeoff profile that was uncharacteristic from previous departures. The investigation was also unable to determine the reason(s) for the right turn/roll and departure from controlled flight.

Text from the NTSB. Open the NTSB docket for WPR17FA041 for the full record.