The Transportation Safety Board of Canada (TSB) released its investigation report into the March 2016 fatal crash of a Mitsubishi MU-2 twin-engine turboprop aircraft in Îles-de-la-Madeleine, Quebec.
The report underlines the risks of continuing an unstable approach to a landing, which is on the TSB Watchlist of key safety issues that need to be addressed to make Canada's transportation system safer.
The accident occurred on March 29, 2016 when the MU-2 aircraft left Montréal/Saint-Hubert Airport for Îles-de-la-Madeleine, Quebec, a two-hour flight. On board were the pilot, a passenger-pilot, and five passengers.
During the final approach, when the aircraft was 1.4 nautical miles west-southwest of the airport, it turned south of the approach path. Aircraft control was lost and the aircraft struck the ground in a near-level attitude. The aircraft was destroyed, and all on board were killed.
The report describes the MU-2 as a high-performance aircraft, which is especially challenging to fly at low airspeed, particularly during sudden applications of engine power.
While in cruise flight, the pilot modified his approach plan by delaying the aircraft's initial descent. This placed the aircraft above the planned descent profile and compressed the time available for the pilot to complete the required checklist activities, while monitoring the aircraft's airspeed, altitude and rate of descent, thereby increasing the pilot's workload.
Under such high workload conditions, the report says that the pilot likely did not recognize that a go-around was an option available to reduce his workload, and he continued with the unstable approach. During the final moments of the flight, a loss of control occurred when the pilot rapidly added full power, at low airspeed and low altitude, which caused an aircraft upset and resulted in the aircraft sharply rolling to the right and descending rapidly. Although the pilot managed to level the wings, the aircraft was too low to recover before striking the ground.
"We have seen too many of these unstable approaches in the past lead to tragic accidents," said Kathy Fox, TSB Chair. "It is important that pilots consider conducting a go-around when an approach is unstable."
Regulators, operators and aircraft manufacturers have defined stable-approach criteria, which pilots are trained to follow. Stable approaches make landings more consistent and predictable—giving pilots time to monitor key elements such as airspeed, altitude, rate of descent and to complete checklists—improving the likelihood of a safe landing.
In this investigation, a crucial source of information was a lightweight recorder that the pilot had developed and installed on board the aircraft, even though it was not required by regulation. The device provided investigators with valuable acceleration and GPS data as well as cockpit audio, allowing them to piece together a detailed history of the flight.
"The benefits of lightweight recorders are obvious: knowing what happened is the first step to understanding why. Although the TSB does not endorse any single product, it would be fair to say that the lightweight recorder on this aircraft can be viewed as an indication of the way forward" said Fox.