On 16 August 2018, a Simpson Air Limited float-equipped Cessna U206G aircraft left Fort Simpson, Northwest Territories, for a sightseeing flight with one pilot and four passengers on board. On arrival at Little Doctor Lake, control of the aircraft was lost during landing and the aircraft capsized. The pilot and one passenger escaped the submerged fuselage. The remaining three passengers were unable to exit the aircraft and drowned.
The investigation found that, for the last 300 feet of the descent, a stable approach profile was not maintained which led to a hard landing and subsequent bounce. With no recovery techniques applied for a bounced landing, the right wing of the aircraft contacted the surface of the lake, and the aircraft nosed over, coming to rest inverted and partially submerged.
Although all doors were functional, the investigation found that the extended wing flaps used for landing had blocked the forward portion of the rear cargo doors. Based on this observation, the TSB immediately issued Aviation Safety Advisory A18W0129-D1-A1 to highlight the significant safety issue involving Cessna 206 aircraft that are fitted with rear double cargo doors. Over the years, the rear double cargo doors have been identified as a risk to passengers in emergency situations. As a result, the TSB and other investigative agencies have been advocating for changes to the door design.
Transport Canada responded to the TSB Safety Advisory by stating its intention to make a formal submission to the U.S. Federal Aviation Administration requiring Cessna to develop, deploy and mandate improvements to the cargo door design to ensure successful egress in the event of an accident on water.
The investigation also highlighted a number of risk factors. In particular, if a passenger safety briefing is incomplete, passengers may not know the process required to escape the aircraft in an emergency. In this occurrence, a pre-flight briefing was provided during which the operation of the rear cargo doors was demonstrated. However, no instructions were provided on what to do if the door was blocked due to flap deployment.
Following the occurrence, the company stopped operating the Cessna 206 on floats. It started providing underwater egress training for all floatplane flight crews, and increased training and experience requirements for new crew members.
See the investigation page