Wreckage from the de Havilland Beaver crash is brought to the surface off Saturna Island. (CBC)

Transportation Safety Board investigators say the lack of safety doors on a seaplane that crashed near Saturna Island, B.C., last year likely contributed to the death of six passengers, including an infant.

The de Havilland Beaver, operated by Seair, crashed into the water on Nov. 29, moments after taking off from Lyall Harbour. All but two people on board died.

Lead investigator Bill Yearwood said the pilot and one passenger were able to escape after the doors beside them popped open. Six other passengers were trapped inside when two other exits jammed shut in the crash, he said.

It is not clear if all of the passengers survived the impact of the crash, but Yearwood said five of the victims were found free of their seatbelts.

"The left cabin door, which is normally used for embarking and disembarking passengers, was jammed shut from the airframe's deformation on impact," the Transportation Safety Board said in an update issued online on Thursday.

Divers also found the right cockpit door jammed shut, the update said.

"The right cabin door and the left cockpit door appear to have popped open. The two survivors were seated next to those two open doors."

Risks previously identified

The de Havilland Beaver, like this one operated by Seair Seaplanes, has a reputation as a reliable aircraft, suitable for flying in remote and difficult conditions. (Seair Seaplanes)

The investigation's preliminary findings echoed the findings from previous board investigations, Yearwood said, including:

• Occupants of submerged seaplanes who survive an accident continue to be at risk of drowning inside the aircraft.
• Occupants who escape a submerged seaplane may drown without floatation assistance.
• Seaplanes may not be optimally designed to allow easy occupant escape while under water.

Yearwood said it is not clear to him why the industry has ignored previous recommendations from safety inspectors to retrofit seaplanes with push-out emergency doors, although he noted the U.S. military has installed the safety doors.

Investigation continues

Yearwood also said the investigation into the crash is continuing and the cause has not been determined. The pilot and surviving passenger have been interviewed, but the wind conditions and the flight path of the plane are still under examination, he said.

"The winds were generally from the southeast, but gusting and variable," the safety board said. "In open areas, the wind was blowing to about 30 knots. After an attempt to take off to the northwest, the pilot turned the aircraft southeast and then took off into the harbour.

"Once airborne, the aircraft remained below the surrounding terrain and during a turn to the left, it descended and collided with the water near the north shore of the harbour."

The aircraft appears to have been in good serviceable condition before impact. Records indicated that there were no outstanding maintenance problems, and that all of its modifications were approved, Yearwood said.