NTSB Identification: ERA11FA480
14 CFR Part 91: General Aviation
Accident occurred Wednesday, August 31, 2011 in Provincetown, MA
Probable Cause Approval Date: 04/10/2013
Aircraft: PIPER PA-28-181, registration: N6249C
Injuries: 1 Fatal,1 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The non-instrument-rated pilot of the single-engine airplane was departing on a dark night from an airport located at the tip of a peninsula. Analysis of global positioning system data showed that the pilot initiated a takeoff from the runway and prior to reaching an altitude of 100 feet, he began turning the airplane on course to the destination airport. After crossing over the left boundary of the runway and with the airplane oriented toward a non-lighted area of the landmass and water below, the airplane ceased climbing and impacted trees about 900 feet beyond the left boundary of the runway. The wreckage path orientation and length were consistent with a shallow, powered descent, and signatures observed on the wreckage were consistent with a relatively level impact attitude. Examination of the wreckage revealed no evidence of any preimpact mechanical failures or malfunctions of the airframe or engine.
Toxicological analysis detected elevated levels of ethanol in postmortem samples of the pilot’s blood, urine, and brain tissue, the distribution of which was consistent with ingestion. The levels of ethanol present in the pilot’s samples were present in levels known to degrade psychomotor performance. Toxicological testing also detected an inactive metabolite of cocaine in postmortem samples of the pilot’s urine, but not in samples of blood. This was a likely indication that the pilot had used cocaine, but neither the drug nor its metabolite was active at the time of the accident.
The circumstances of the accident are consistent with the pilot experiencing a form of spatial disorientation known as the somatogravic illusion, in which a pilot misperceives acceleration cues as increasing pitch and makes corrective nose-down inputs. These circumstances include the accelerating phase of flight during takeoff, the dark night lighting conditions associated with an early turn on course, and a non-instrument-rated pilot whose judgment and psychomotor performance were degraded by alcohol consumption. The airplane subsequently impacted the trees and terrain below in a shallow, un-arrested descent.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot’s failure to maintain adequate clearance from trees and terrain during the initial climb. Contributing was spatial disorientation due to a vestibular illusion and the pilot’s likely impairment due to alcohol consumption. Full narrative available
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