SAN FRANCISCO -- The Federal Aviation Administration is investigating why anpassenger plane ignored repeated orders by air traffic control at San Francisco International Airport to abort a weekend landing, officials said Tuesday.
After landing safely, the plane reported a radio problem and Air Canada subsequently said the cockpit never received the orders.
The Sunday night incident happened three months after another Air Canada jet with 140 people on boardat San Francisco's main airport.
The close call in July prompted the FAA to issue new rules for nighttime landings and control tower staffing at the airport.
The latest incident involved Air Canada Flight 781 from Montreal, an Airbus A320 that was given initial clearance to land when it was about 6 miles from the airport, FAA spokesman Ian Gregor said. The cockpit acknowledged the instruction.
But air traffic control then issued multiple orders for the jet to "go around" because it believed another plane may have been in the runway, Gregor said in a statement.
Audio from the control tower posted by The East Bay Times indicates that the Air Canada flight was told six times in less than a minute to "go around," or interrupt its landing procedure. The instruction was met with silence, according to the audio clip.
The air traffic control supervisor then used a flashing "red light gun" shined out from the control tower windows toward the plane to alert the crew to go around, Gregor said. Doing so is a standard procedure when an air crew does not respond to radio instructions.
"After landing, the Air Canada crew told the tower they had a radio problem," Gregor said. He said the FAA was investigating.
He said that a radar replay showed the runway was in fact cleared of the earlier arrival when the Air Canada flight landed.
Air Canada spokesman Peter Fitzpatrick also said the company was investigating the incident.
"After receiving proper clearance to land it proceeded to do so and landed normally. Upon landing the crew was informed the tower had attempted unsuccessfully to contact the aircraft, however the message was not received by the crew," Fitzpatrick said.
In July, an Air Canada jet descended toward a taxiway holding four other planes rather than its assigned runway. The Air Canada pilots descended to less than 100 feet above the ground and flew over another plane before aborting the landing.
"We're talking less than a second from disaster," Ross Aimer, a retired airline captain and CEO of Aero Consulting Experts, told CBS News transportation correspondent Kris Van Cleave in July.
In August, the FAA issued new procedures to apply when a runway parallel to a plane's designated runway is closed, as it was July 7, possibly contributing to the confusion.
When an adjacent runway is shut down at night, air traffic controllers will no longer let pilots make so-called visual approaches to land. Instead, they must use instrument landing systems or satellite-based systems to line up for the correct runway, according to the new rules.
The FAA said the agency also will require two controllers in the airport tower during busy late-night periods. Only one controller was working during the Air Canada incident in July.