Federal Aviation Administration officials are investigating an incident at San Francisco International Airport involving an Air Canada plane that appeared to have a radio communication breakdown while landing.
FAA spokesman Ian Gregor said air traffic control cleared Flight 781, an Airbus A320, to land on Runway 28R on Sunday night. The Air Canada crew acknowledged the instruction when they were about six miles away from the airport, Gregor said.
"The tower controller subsequently instructed the Air Canada crew multiple times to execute a go-around because he was not certain that a preceding arrival would be completely clear of the runway before the Air Canada jet reached the runway threshold," Gregor said, adding the crew onboard the plan did not acknowledge any of the controller's instructions.
A supervisor then resorted to using a red light gun to alert the Air Canada flight to go around. Gregor said flashing a light gun is standard protocol when an air crew is not responding to radio instructions.
Air Canada Flight 781 landed on Runway 284 at 9:26 p.m. The Air Canada crew after landing told the tower they had a radio problem, according to Gregor.
"A radar replay showed the preceding arrival was in fact clear of the runway when Air Canada landed," Gregor said.
Aviation expert Mike McCarron said an incident like the one on Sunday "does not happen very often."
"While not alarming, it certainly is of some concern that for some reason for basically a five-six minute stretch, the aircraft never heard any of the radio calls from the tower," he said.
McCarron added that factors such as pilot error or a mechanical malfunction with radio communications could have triggered the communication disruption.
Sunday's incident follows a July 7 incident at SFO when an Air Canada jet nearly struck planes on the ground.
In response to the close call, the FAA issued new rules for nighttime landings and control-tower staffing at SFO.