On June 4, 2004, a Cessna A185F seaplane departed Four Mile Lake, Alta., on a VFR flight to Taltson River, N.W.T. The purpose of the flight was to transport three passengers to a site on the river known as Ferguson’s Cabin. At approximately 17:00 Mountain Daylight Time (MDT), as the aircraft was landing on the water near Ferguson’s Cabin, the left float dug in, and the left wing struck the water. The aircraft immediately cartwheeled and came to rest floating inverted in the river, with only the bottoms of the floats visible at the surface. The pilot and the front seat passenger sustained serious injuries; however, they managed to exit the submerged and damaged aircraft through a broken window in the left cabin door. Four fishermen in boats responded to the accident, removed the survivors from the cold water and transported them to a warm shelter. The rear seat occupants drowned. One decedent was found inside the aircraft and the second decedent was found two days after the accident, outside the aircraft, near the position where the aircraft had crashed, in 55 ft of water.

Findings as to causes and contributing factors

1.        For undetermined reasons, the aircraft contacted the water in a nose-low attitude on landing or entered a nose-low attitude shortly after touchdown. As a result, the left float dug in and the aircraft cartwheeled.

2.        The survivors were unable to locate the interior door handles after the seaplane became inverted and submerged in the water, thus preventing them from using the doors as emergency exits.

Findings as to risk

1.        Seaplane passengers who do not receive underwater egress information during a pre-flight briefing or on a safety-feature card may not be mentally prepared for an emergency exit from a submerged aircraft.

2.        The life preservers were not stowed in an area that made them easily accessible to the occupants.

3.        The pilot and front passenger were not wearing their available shoulder harnesses during the landing, as required by regulation.

4.        The baggage was not secured in the baggage compartment, which increases the risk of injury to the occupants during the crash or could impede their exit from the aircraft.

5.        The weight of the baggage in cargo area 1 probably exceeded the compartment’s structural limit and increased the probability of damage to the aircraft.

Safety action taken

Transport Canada (TC) published a comprehensive article on underwater egress in the Aviation Safety Letter (ASL) 1/2005 and updated safety promotion material. The Department also reviewed the safety-feature card/placard information required under section 703.39 of the Canadian Aviation Regulations (CARs), and this information was deemed appropriate for seaplane operations.

Safety concern
Risk of Drowning in Survivable Seaplane Accidents

Based on historical data, occupants of submerged seaplanes who survive the accident continue to be at risk of drowning inside the aircraft. The TSB believes that existing defences against drowning in such circumstances may not be adequate. In light of the potential loss of life associated with seaplane accidents on water, the TSB is concerned that seaplane occupants may not be adequately prepared to escape the aircraft after it becomes submerged. The Board is also concerned that seaplanes may not be optimally designed to allow easy occupant egress while under water.