Accident Description
A commercial certificated pilot was departing a remote bay with five passengers in an amphibious float-equipped airplane on the return portion of a Title 14, CFR Part 135 sightseeing flight. The pilot began the takeoff run toward the north, with the wind from the north between 15 to 20 knots, and 4 to 6 foot sea swells. When the airplane had climbed to about 10 to 15 feet, the pilot reported a windshear encounter that pushed the airplane down. The airplane's floats struck a wave, missed about 4 to 5 swells, and then struck another wave, producing a loud "bang." The company guide, seated in the right front seat, informed the pilot that the right float assembly was broken and displaced upward. The airplane cleared a few additional swells and then collided with the water. Both float assemblies were crushed upward, and the left float began flooding.
Evacuation and Rescue
After the collision, the guide exited onto the right float and made a distress call via satellite telephone. All occupants donned life preservers as the airplane began sinking. The pilot stated that after about 15 minutes, the rising water level inside the airplane necessitated an evacuation; all occupants exited into the water and held onto the right float as the airplane rolled left. The airplane remained floating from the right float and was moved away from shore by wind and wave action. Within about 5 minutes, one passenger was washed away from the float, and two more followed shortly thereafter. The pilot lost his grip on the float after about 5 minutes in the water and does not remember anything further until regaining consciousness in a hospital, where he was told by medical staff that he had been severely hypothermic.
U.S. Coast Guard aircraft, already airborne on a training mission, diverted to rescue the occupants. At about 1320, a C-130 flew overhead and began dropping inflatable rafts. The company guide was the only person able to climb into a raft. When helicopters arrived, they completed the rescue using a hoist and a rescue swimmer. The passengers reported that they also were unable to hold onto the airplane after entering the water, became unconscious, and were severely hypothermic upon reaching a hospital. The airplane was not equipped with a life raft, and was not required to be so equipped.
Probable Cause
The probable cause, as determined by the official investigation, was the pilot's inadequate evaluation of the weather conditions and his selection of unsuitable terrain (rough water) for takeoff, which resulted in a collision with ocean swells during takeoff initial climb, and a hard emergency landing and a roll over. Factors contributing to the accident were a windshear, rough water, and buckling of the float assemblies when the airplane struck the waves.