“Temporary unresponsiveness” of the 62-year-old, 28,000-hour airline transport pilot probably caused the crash that killed Alaska Sen. Ted Stevens and four other passengers on Aug. 9, 2010, said the National Transportation Safety Board at a public meeting May 24.
Why the pilot became unresponsive during the 50-mile flight from a corporate-owned lodge to a salmon fishing camp “could not be established from the available information.”
The amphibious-float-equipped turbine de Havilland Otter struck mountainous terrain in a climbing left turn about 10 miles northeast of Aleknagik, Alaska, 15 minutes after departure. Four passengers survived the accident, among them former NASA chief Sean O’Keefe. In an opening statement, NTSB Chairman Deborah A.P. Hersman summarized the NTSB’s findings from “nine months of exhaustive investigation, numerous consultations, and a host of expert opinions.”
Minutes before the crash, the turbine Otter, equipped with amphibious floats and state-of-the-art avionics, was reported on course. The pilot, Hersman said, was “highly experienced” and familiar with the route. Days prior, he had lost his son-in-law in another Alaska aviation accident. In 2006 the pilot had suffered a stroke, and in 2008 and 2009 he had received a first-class medical certificate. The pilot had inhibited the terrain awareness and warning system's aural voice and pop-up text alerts.
In a set of 20 conclusions about the crash, the NTSB described the regional flight surgeon’s issuance of an unrestricted first class medical certificate to pilot Theron Smith, without certain additional medical consultations, as “inappropriate” considering a stroke Smith suffered in 2006.
To obtain a medical certificate after a stroke, the FAA requires a two-year recovery period or more depending on the severity of the stroke followed by an extensive cardiovascular evaluation and neurological evaluation. The evaluations include an outline of the entire medical history (including family history), results of any testing performed, an electrocardiogram with complete tracings, an exercise stress test, an echocardiogram, a bilateral carotid ultrasound, and a report by a Board Certified Neurologist to include a detailed report of a recent neurological examination among other requirements. Additionally, if the FAA determines that another opinion is required to issue the medical certificate, they can request additional information or submit the airman's information to a consultant for review and advice.
The board could not determine if a medical condition played a role in the accident. It said that the lack of a cockpit voice recorder system hindered determination of a cause of the crash.
The NTSB issued recommendations on detailed annual inspection procedures for emergency locator transmitters, having found during the crash probe that the accident aircraft’s ELT had become separated from its antenna. No ELT signal was detected after the crash.
The report criticized the pilot’s failure to brief passengers about on-board emergency equipment including a satellite telephone. The NTSB specifically addressed a recommendation to AOPA, urging the association to educate pilots on the importance of providing a briefing on emergency equipment location and use.
AOPA Foundation President Bruce Landsberg said the foundation’s Air Safety Institute will address the recommendation with educational resources. “We endorse the board’s recommendation [for pilot education], and we will be putting together guidance for pilots of Part 91 operations on preflight briefings,” Landsberg said.
The pilot would have had aural and visual warnings of an impending crash about 30 seconds before impact—instead of only about four seconds before the crash—had he not inhibited an on-board warning system, the NTSB said.
Smith’s transient incapacitation or impairment could explain the circumstances of the crash, said the NTSB, but it was not possible to determine whether such a condition existed. Neither of the two surviving passengers who were awake at the time of the accident was seated with a clear view of the pilot, the board said in its synopsis.
“What we do not know—and may never know—is what happened in the last three minutes of that fatal flight,” Hersman said.
Hersman recognized Smith’s contributions to safety of flying in Alaska during his career, and she acknowledged the respect he commanded in the aviation community. “Today's discussions are difficult because aviation in Alaska is safer today than it was in the past, due to the efforts of many of the people on the airplane, including the accident pilot who was known by his fellow Alaska Airline pilots as the ‘Legend of Alaska’ and who dedicated much of his life, professionally and personally, to aviation safety efforts in Alaska,” she said.
The NTSB characterized the FAA’s “internal guidance for medical certification of pilots following stroke” as “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 summary addressed weather systems and information, noting that “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.”
A recommendation urged a test program for collecting and relaying real-time weather information from datalink-equipped aircraft to the Alaska Unit of the National Weather Service.