The National Transportation Safety Board said the crash of a glacier viewing flight near Petersburg on June 4, 2013, which killed one passenger and seriously hurt two others, was caused by the pilot's failure to maintain adequate altitude and airspeed, which in turn led to a stall, spin and subsequent crash. This was the fourth fatality accident involving loss of control in Alaska for 2013. Of the six passengers aboard the flight, New Mexico resident Thomas Rising did not survive.
The float-equipped de Havilland DHC-2 aircraft, operated by Pacific Wings as a sightseeing flight for cruise ship passengers, collided with mountainous, tree-covered terrain about 14 miles east of Petersburg at 3:31 p.m. It had departed the seaplane facility at Petersburg Harbor about 10 minutes earlier with an intended route to LeConte Glacier. According to the company director of operations, the regular tour flight typically took about 45 minutes.
The closest weather reporting facility to the accident site was Petersburg Airport, which reported wind, calm, visibility of 2 1/2 miles with light rain and mist. Clouds were scattered at 500 feet, broken at 1,300 feet and overcast at 1,800 feet. One of the passengers told investigators that the aircraft was never in the clouds during the flight and visibility was good at the time of the crash. The NTSB did not cite weather as a factor in the accident.
During an interview with an NTSB investigator two days later, the pilot stated weather conditions deteriorated throughout the day and estimated a ceiling of 2,000 feet, light rain, and fog along the mountain ridges. He was flying to LeConte Glacier via Horn Cliffs and while approaching a pass "...initiated a climb by adding a 'little bit' of flap, approximately 1 pump of the flap handle actuator, but did not adjust the engine power from the cruise power setting. He noted his airspeed at 80 knots, with a 200 feet per minute climb on the vertical speed indicator." The pilot said he had trouble seeing over the cowling due to the nose high attitude and then saw trees in his flight path. He began an immediate left turn, whereupon the aircraft stalled and soon crashed into terrain.
The passenger who was interviewed by the investigator said he heard nothing unusual during the flight until "...the engine speed seemed to increase significantly just before impact."
According to company records, the pilot had about 4,850 flight hours, of which about 1,465 were in the de Havilland DHC-2 aircraft. The flight was his fourth flight and third tour flight of the day. He'd flown 45.7 hours in the previous 30 days.
This accident is the fourth Alaska fatality from 2013 to involve loss of control, which is the leading cause of fatality accidents in U.S. aviation. To reduce such grim statistics a group comprised of representatives from governmental agencies, user groups and industry completed a study released in 2012 that included the recommendation for installation of angle of attack indicators in aircraft. AOA indicators are designed to clearly show pilots when the aircraft is in danger of an aerodynamic stall. If a stall occurs at low altitude, the pilot rarely has adequate time to recover before a crash.
Reach Colleen Mondor at colleen@alaskadispatch.com.
By COLLEEN MONDOR
colleen@alaskadispatch.com