VANCOUVER — The Transportation Safety Board will release its final report today on a deadly crash that renewed the focus on float plane safety around British Columbia's mountainous coastal terrain.

Six people died, including a mother and her six-month-old baby, when the Seair Seaplanes Ltd. single-engine de Havilland Beaver crashed and sank in Lyall Harbour, off Saturna Island, in November 2009.

The pilot and a passenger survived after the doors closest to them popped open, but the remaining passengers couldn't escape from exits jammed shut when the plane's fuselage twisted on impact.

A preliminary report, released a few months after the crash, said the accident echoed findings of previous investigations that found people who survive the crash risk drowning in the plane because they're trapped.

"Seaplanes may not be optimally designed to allow easy occupant escape while under water," the report said.

It also said even those inside float planes who escape may end up drowning because they aren't wearing life jackets.

"Five of the passengers remaining in the aircraft were free from their seatbelts," the preliminary report stated, indicating the passengers survived the impact and were prepared to escape.

Dr. Kerry Morrissey and her baby daughter Sarah were among the dead. The other victims were Catherine White-Holman, Thomas Glenn, Cindy Shafer and Richard Haskett.

The early report said wind was blowing up to 30 knots that day and the pilot attempted to take off to the northwest, then turned the aircraft in the harbour.

Once airborne the plane remained below the surrounding terrain and plunged into the water attempting a left turn.

While there was an immediate emergency response, the plane sank quickly and only the surviving pilot and one passenger were rescued.

The TSB said then it was focusing its investigation on issues surrounding push-out emergency exits on float planes, training for air crews on how to get out of a submerged planes, pilot flight training in mountainous areas and wearing life jackets.

Saturna Island is the easternmost of the Gulf Islands located in the Georgia Strait between Vancouver Island and the mainland of British Columbia.

The safety board doesn't assign fault or blame in such accidents, but tries to advance safety and make recommendations to Transport Canada, the body in charge of implementing safety improvements.