The glider plane carrying a student pilot and instructor who were killed in a crash in southern Alberta last summer was released from the tow plane during a turn — which isn’t normal, according to the Transportation Safety Board.
Allan Wood, an experienced pilot, and 18-year-old student Adam Leinweber were flying near the Cu Nim Gliding Club on July 26 when the glider they were in crashed with the tow plane that led them into the sky.
Investigators with the TSB arrived at the crash site the next morning to start their investigation, which was released publicly on Feb. 10.
Glider released in a turn
According to the TSB, while in flight, the tow plane radioed to the glider to do some bank turns — which investigators determined wasn’t part of the plan before the crews took off.
The tow plane, flying at about 5,900 feet, did a left, 30-degree turn followed by a right, 90-degree bank turn and released from the towline halfway through that second turn.
“Typically, a glider pilot will release from the towline when the two aircraft are in straight and level flight,” the TSB report said.
“When the tow plane reached the anticipated release point, the glider had already released; however, the tow plane pilot was not aware.”
The glider crew radioed to the tow plane to thank the pilot for the tow.
Though the tow plane pilot couldn’t see the glider, he made an 80-degree left “clearing turn,” which is standard procedure after a glider is released.
When the pilot still couldn’t see the glider, he turned right in hopes of finding the plane rather than immediately heading to land.
He then turned left again, without trying to radio with the glider crew, trying to see the glider.
Just 34 seconds after the glider was released, the tow plane’s propeller struck the tail of the glider and the stabilizers broke off.
“The glider entered a dive from which it was unable to recover and struck terrain in a near-vertical attitude,” the TSB said, adding both the student pilot and instructor were killed.
The TSB said both men inside the glider were wearing parachutes at the time of the crash.
The glider was destroyed when it crashed into the ground. The small plane’s stabilizers were found 1,200 feed and 1,600 feet away from the crash site and bits of fibreglass from the glider were embedded in the tow plane’s propeller.
Collision-avoidance software not working
The TSB found the tow plane, a 1970 Cessna 182N single-engine plane, had a PowerFLARM Core collision-avoidance system, but it wasn’t working.
The FLARM system calculates and broadcasts future flight paths to any nearby planes while also gathering data on other aircrafts’ flight paths, according to the TSB. It then predicts the collision risk for each aircraft and if a crash is imminent, FLARM alerts the pilots so they can try to avoid it.
Investigators found the system had either been intermittent or not working at all throughout most of 2019.
The issues with the software weren’t logged in the plane’s journey log, the TSB said, which is required.
The PowerFLARM system in the glider was working the day the crash happened.
The TSB said in the case of this crash, there were no procedures in place for the pilots once the tow plane lost visual contact with the glider, which the Cu Nim Gliding Club needs to implement.
“Relying solely on visual detection increases the risk of collision while in uncontrolled airspace,” the TSB said. “Pilots are encouraged to broadcast their intentions to maintain the situational awareness of other aircraft.”
The TSB also said the anti-collision systems in aircraft need to be maintained.
Both the pilot and student were members of the Cu Nim Gliding Club, which said in an emailed statement it would be “carefully studying the report and will be taking the safety messages extremely seriously.”
“Throughout its 60-plus years of operation, the Cu Nim Gliding Club has prided itself on the safety and well-being of its members,” president Kerry Stevenson said.
“The executive and membership continue to collectively grieve the loss of our friends and remain committed to advancing the passion of soaring safely above the skies of southern Alberta.”