Pilot Debrief

PIPER PA-28-181 near Provincetown, MA — 2011-09-01

Final reportERA11FA480
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Date
2011-09-01
Location
Provincetown, MA, USA
Airport
PVC
Aircraft
PIPER PA-28-181
Registration
N6249C
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Initial climb

Probable cause

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.

Contributing factors

Contributing was spatial disorientation due to a vestibular illusion and the pilot’s likely impairment due to alcohol consumption.

NTSB narrative

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.

Analysis

Primary failure mode
Spatial disorientation
First missed decision gate
Pilot could have delayed takeoff until conditions improved or sought instrument training.

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 12 docket documents
View NTSB final reportView NTSB docket

Docket documents12

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