NTSB Identification: SEA96LA113.
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Accident occurred Thursday, June 06, 1996 in ABERDEEN, ID
Probable Cause Approval Date: 05/23/1997
Aircraft: Ayres S2R, registration: N5686X
Injuries: 1 Serious.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The simulated aerial application flight occurred about 0800 on the morning after the pilot made a 3-day, 22-1/2 hr drive; he had slept an average of less than 5-1/2 hours each night for the 3 previous nights, awakening at 0445 that morning. He reported '...my hydration...may have been low.' He had flown only 1 to 2 hrs during the previous 90 days, with no recent performance of abrupt or high-G maneuvers. He stated he was 'wound up with anticipation' before starting work (in his new job). He reported that after 10 to 12 touch-and-go landings, using steep pattern turns, followed by 15 to 20 practice swaths of a field, he experienced symptoms resembling those of motion sickness. He said he discontinued steep maneuvers, opened the air vents, and unzipped his Nomex flight suit. then he began feeling better. He then decided to resume swathing (contrary to published FAA advice regarding motion sickness encounters), but immediately after doing so, he experienced even more intense symptoms. He attempted to return to the airport, but en route, he started feeling clammy, sweaty, and light-headed; the next thing he remembered was 'waking up' in the aircraft after it crashed. A neurologist who evaluated the pilot reported he thought the pilot had a 'vasovagal response', which medical references describe as fainting in response to pain, shock, stress, or fear.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

pilot's improper planning/decision, and subsequent incapacitation, which resulted in a loss of aircraft control and collision with the terrain. Factors relating to the accident were: pilot fatigued from a long-distance drive with minimal rest, physical impairment of the pilot due to low hydration, his lack of recent experience in abrupt/high-G maneuvering, pilot anxiety/apprehension, the resultant motion sickness of the pilot, and his improper decision to continue flight after experiencing a physiological disturbance, all of which led to vasovagal syncope.

Full narrative available

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