Board Meeting Synopsis: http://www.ntsb.gov/events/2011/Alek...K/synopsis.htm
- The investigation determined that the pilot was certificated and qualified in accordance with Federal regulations.
- Examinations of the recovered engine, propeller, and airframe components revealed no evidence of any preimpact failures.
- The weather conditions forecasted for and observed in the area on the day of the accident did not appear to be exceptional compared to the conditions that the pilot experienced on previous flights.
- The airplane was in a climbing left turn when it collided with terrain, and flight control inputs occurred shortly before terrain impact.
- The airplane's radar altimeter system provided both aural and visual altitude alerts about 4 to 6 seconds before impact, which likely prompted the pilot to take aggressive action on the flight controls, resulting in the airplane nose-up pitch and left-bank angles evident at the accident site.
- Had the pilot not inhibited the terrain awareness and warning system's aural voice and pop-up text alerts, the system would have provided an aural and visual alert up to 30 seconds before the impending collision.
- A deliberate execution of a left turn toward the rising terrain by the accident pilot in any weather condition would require a lack of situational awareness that is inconsistent with the pilot's reported level of proficiency, typical safety practices, and familiarity with the area.
- A medical condition leading to transient incapacitation or impairment could explain the circumstances of this accident; however, it is not possible to determine whether such a scenario occurred.
- Although the pilot had some precursors for the development of fatigue, and the accident circumstances are consistent with fatigue impairment or a sleep event, there is insufficient evidence to determine whether fatigue-related performance or alertness impairments played a role in the accident.
- The accident pilot's recent major life events placed him at an elevated risk for stress at the time of the accident, but it is not possible to determine how, or to what extent, this stress may have affected his performance.
- A crash-resistant flight recorder system that captures cockpit audio, images, and parametric data would have substantially aided investigators in determining the circumstances that led to this accident.
- Had the emergency locator transmitter remained attached to its mounting tray, it would not have become separated from its antenna, and its signals likely would have been detected soon after impact; as a result, rescue personnel would have received timely notification of the accident and its location and could have reached the survivors hours earlier, when the weather and daylight were more conducive for their evacuation.
- Had the pilot informed the passengers about the location and use of all survival and emergency communication equipment on board the airplane, particularly the satellite telephone, the passengers may have been able to find and use the telephone to expedite the initiation of search and rescue activities after the accident.
- Based on the severity of the nonsurvivable traumatic injuries sustained by the pilot and the four passengers who died at the scene and the relative stability of the serious injuries of the surviving passengers, the delay in accident notification did not result in additional fatalities.
- The activities of the volunteer rescuers and the emergency medical personnel aided in the comfort of the surviving passengers while they waited for rescue and may have prevented additional passenger fatalities due to hypothermia from environmental exposure.
- The Alaska Regional Flight Surgeon's decision to issue the pilot an unrestricted first-class airman medical certificate, based largely on a local neurologist's in-office evaluation and without conferring with any other Federal Aviation Administration physicians or consultants or attempting to address the etiology of the hemorrhage, the likelihood of recurrence, or the extent of any remaining cognitive deficit, was inappropriate.
- It is not clear that a sufficiently thorough aeromedical evaluation of the pilot would have denied the pilot eligibility for a first-class airman medical certificate; however, a more rigorous decision-making process for evaluating this pilot with a history of intracerebral hemorrhage would have decreased the potential for adverse consequences.
- The Federal Aviation Administration's internal guidance for medical certification of pilots following stroke is inadequate because it is conflicting and unclear, does not specifically address the risk of recurrence associated with such an event, and does not specifically recommend a neuropsychological evaluation (formal cognitive testing) to evaluate potential subtle cognitive impairment.
- The known, widespread Automated Weather Sensor System site deficiencies, if not corrected as expeditiously as possible, will continue to adversely affect the weather reporting network's ability to offer adequate coverage for providing National Weather Service forecasters and pilots with accurate ceiling and/or precipitation information.
- The use of data link-equipped aircraft to collect meteorological data and to disseminate this information may provide National Weather Service forecast offices with a more widespread, reliable meteorological dataset to improve the quality of weather forecast products.
The National Transportation Safety Board determines that the probable cause of this accident was the pilot's temporary unresponsiveness for reasons that could not be established from the available information. Contributing to the investigation's inability to determine exactly what occurred in the final minutes of the flight was the lack of a cockpit recorder system with the ability to capture audio, images, and parametric data.