The U.S. National Transportation Safety Board has determined the Airbus came within 26 feet vertically of one of four aircraft waiting for their turn on a taxiway. The taxiway is adjacent to and parallel with the runway the crew intended to line up with.
The NTSB report says the aircraft overflew one of the waiting planes and was over the second one when controllers called the go-around.
“I find it remarkable that the Air Canada crew had still not fully comprehended their situation as they were passing over the second airliner, when the tower called for the go-around,” aviation writer and consultant Max Trescott told the Washington Post.
Both pilots hve been interviewed by U.S. authorities and the flight data and cockpit voice recorders have been pulled for analysis.