A Transportation Safety Board investigation has identified inaccurate transponder information as a factor in an incident where two planes were at risk of colliding on a runway at Canada’s busiest airport.

The TSB says an Air Canada Embraer 190 jet had just begun its takeoff at Toronto’s Pearson International Airport on March 7th, 2020 when it hit a bird and made a radio call to say it was aborting its takeoff.

But the investigation found the call was not heard by air traffic control or the crew of an Air Canada Boeing 777 lined up behind it and the second jet was accelerating when it noticed the other plane was still on the runway.

The investigation found that while compliant with current standards, the Embraer 190’s transponder transmitted that the aircraft was in the air after it accelerated past 50 knots.

It says in the wake of the incident, NAV CANADA published an urgent bulletin reminding all Toronto Tower personnel that alerts may not be generated when certain aircraft are departing, and reminded controllers to monitor such situations closely.