The National Transportation Safety Board released its findings Tuesday into the plane crash that killed former Sen. Ted Stevens, placing some blame with the pilot and raising questions about whether he should have been cleared to fly after suffering a stroke.
The report found no definitive cause for the crash that killed Stevens, the pilot and three others after the amphibious plane slammed into a mountainside. But the board pointed blame in the direction of the pilot and took the Federal Aviation Administration to task over its guidelines for clearing pilots to fly after suffering strokes.
The board, at a hearing in Washington, determined the probable cause of the crash to be the "temporary unresponsiveness" of 62-year-old pilot Theron "Terry" Smith "for reasons that could not be established from the available information."
Investigators said they went through a number of possible scenarios about the pilot: Was he depressed or distracted? Was he tired or stressed by recent major events in his life that included including the loss of his son-in-law shortly before the crash? Did he suffer a seizure or otherwise become incapacitated?
The NTSB's Malcolm Brenner said investigators even looked at the possibility that this was a suicide attempt, given how far off-route the plane was, but found no evidence of that. Smith, an experienced pilot familiar with the flight path the day of the crash, was described as being in a good mood on the day of the crash, Brenner said.
Results of toxicology reports previously released by the NTSB showed no drugs or carbon monoxide detected in Smith's blood.
The plane was equipped with a terrain awareness and warning system that would have notified Smith when he was approaching treacherous mountain areas. But the warning system was disabled.
That means Smith had as little as four seconds to respond as the plane approached the mountain it eventually slammed into, as opposed to an alert of up to 30 seconds had the system been turned on, the NTSB said.
According to NTSB, Smith had been grounded from flying from March 2006 to April 2008 due to a stroke, and medical records reviewed by the agency showed he had an "extensive" family history of "intracranial hemorrhages at young ages."
Questions were also raised during Tuesday's hearing about the FAA's guidance for determining pilots' readiness to return to flying after suffering strokes. The board found the agency's guidance for medical certification in such cases inadequate, saying it doesn't address the risk of recurrence or recommend formal cognitive testing to check pilots for possible impairments. The board recommended that FAA address the issue.
The NTSB has said Smith's applications for medical certificates from the FAA in 2008 and 2009 did not mention visits to a naturopathic practitioner for a facial twitch said to have started before his stroke and to have worsened with stress or fatigue.
FAA spokesman Les Dorr said his agency changed its policy following a March 2010 summit and now requires a neuropsychological evaluation — essentially formal cognitive testing — for any pilot that has suffered a "significant" stroke.
That requirement wasn't in place when Smith received his medical certification and the board said it's not clear that a "sufficiently thorough aeromedical evaluation" would have rendered him ineligible for that certification. 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 board found.
The passengers in the plane included Stevens and former NASA chief Sean O'Keefe and his son, who was in the copilot's seat and asleep at the time of the crash. Four people, including O'Keefe and his son, were injured.
Stevens and O'Keefe were among the guests at a General Communications Inc. lodge flying to a salmon fishing camp the afternoon of Aug. 9. The other victims who died were William "Bill" Phillips Sr.; Dana Tindall, 48, an executive with GCI; and her 16-year-old daughter, Corey Tindall.
Stevens' family thanked the NTSB and those involved in the rescue effort. The family also cited Stevens' commitment to improving aviation safety — a cause he fought for, given Alaskans' heavily reliance on flying to get around, during his 40 years in the Senate. The family said it hoped the board's recommendations will help further the goal of better aviation safety.
Efforts to reach Smith's widow weren't immediately successful.
The board also recommended that FAA require that crash-resistant flight data recorders that provide audio and video be installed in all existing turbine-powered, non-experimental, non-restricted category aircraft that currently are without cockpit voice or flight data recorders. This is a recommendation the board has made before; FAA has not mandated the recorders.
The board also recommended the agency require detailed annual inspections to ensure emergency locator transmitters are mounted properly. The transmitter on the plane that crashed became dislodged and separated from its antenna. Had that not happened, the board found its signals "likely would have been detected soon after impact."
Instead, hours passed from the time of the crash to the wreckage being spotted, and poor weather hampered rescue efforts, leaving the survivors to spend the night on the mountainside. A satellite phone on board the plane went seemingly unnoticed. Investigators said they did not believe a quicker response would have made a difference for those who died.
Last month, NTSB released hundreds of pages of documents stemming from its investigation, ranging from the pilot's medical history to a review of weather conditions. Several interviews given to NTSB indicated the weather was dreary earlier the day of the crash but had improved by lunchtime. Investigators could not determine weather conditions at the crash site at the time of the accident; the reporting station at the Dillingham airport was 18 miles away.
There was no indication the plane had mechanical problems before the trip.
NTSB chairwoman Deborah Hersman said it's rare for so many people to work so long on an investigation without an agreed upon conclusion. But she said there was limited factual data to work from, leaving investigators without significant evidence to support any single theory.