A bird strike that caused an engine compressor failure has been formally identified as the cause of last year's fatal crash of a Canadian military Snowbird demonstration jet in Kamloops, B.C.
The Royal Canadian Air Force's Directorate of Flight Safety released its final report today on the accident, which took place on May 17 of last year and killed Capt. Jenn Casey, the public affairs officer for the aerobatics team.
The investigation found that a single, small bird was sucked into the engine of the aircraft — Snowbird 11 — following take-off.
That resulted in a compressor stall and a loss of thrust as the aircraft was trying to climb.
"Evidence suggests that the damage caused by the bird ingestion was insufficient for it to cause a catastrophic failure but rather the engine most likely continued running, albeit in a stalled condition," the flight safety report concluded.
After his aircraft lost power, the pilot, Capt. Richard MacDougall, tried to turn back toward the airport. During that manoeuvre, "the aircraft entered an aerodynamic stall and the pilot gave the order to abandon the aircraft," the military said in a statement.
"Snowbird 11's power loss could not have come at a worse time – low altitude, low airspeed, proximity to another aircraft, and in the vicinity of a built-up area," said Col. John Alexander, the Air Force's director of flight safety.
The aircraft turned and went into a steep nose dive before hitting the ground in a residential neighbourhood. It was completely destroyed.
The final report said MacDougall and Casey, originally from Nova Scotia, ejected from the aircraft "at low altitude and in conditions that were outside safe ejection seat operation parameters."
The pilot ordered the aircraft abandoned by saying "pull the handle." The flight safety report said the commonly used word "eject" is supposed to be called out in rapid succession "in a clear and loud voice."
Investigators found that Casey fired her ejection seat point-four seconds after the pilot.
"This difference in wording may have contributed to the overall confusion/uncertainty of the situation which resulted in the passenger ejecting second," the investigation said.
The report said the pilot may have been surprised that the plane had gone into a stall, which could have affected his choice of words.
Video evidence shows that Casey's ejection seat also flew backwards for a few seconds after it was clear of the aircraft, something investigators have been unable to completely explain.
They suggested several possible explanations — including interference from items stuffed between the seat and the side of the cockpit, or the possibility that Casey's arms and legs were extended into the slipstream, causing the whole device to yaw backwards.
The direction of the seat is significant because investigators say it delayed Casey's drogue chute from fully deploying.
Emergency training needed
The tragic accident "reinforces the importance of continuous, situation-specific training to minimize reaction time in an emergency and the importance of a timely decision to eject," said Alexander.
In a preliminary report issued in June of last year, investigators said video footage from the crash showed a bird was very close to the right-side air intake for the aircraft's single engine during takeoff. It's possible the bird struck the air intake, the report suggested.
Such strikes are not uncommon. The U.S. Federal Aviation Administration estimates that aircraft collisions with birds cause damage worth US $400 million each year. As many as 200 people have died in crashes such as this.
As a matter of routine, flight planners are expected to take careful precautions against bird strikes, especially during migratory season.
Investigators say the Kamloops airport took all the proper precautions.
MacDougall suffered severe injuries and has since recovered.
The flight safety report recommends additional training for CT-114 aircrew to better prepare them for an engine failure after take-off in a low-level environment.
It also recommends changes to the ejection procedure.