WASHINGTON (CBS News) — It could have been one of the worst aviation disasters in history.

Last Friday night, an Air Canada flight lined up to land on a taxiway in San Francisco where four other airliners were waiting to take off.

It pulled up just in time.

On Friday, Canada’s Transportation Safety Board said early indications are the Airbus A320 came within just 29 feet of one plane and “overflew the first two aircraft by 100 feet.”

“We’re talking less than a second from a disaster,” said Ross Aimer, a retired airline captain and CEO of Aero Consulting Experts.

“It is an easy thing to do for mistaking a taxiway with a runway, especially on a dark night,” he said.

About a half-mile out, the Air Canada pilots seemed to realize something was wrong, but continued anyway.

“Air Canada 759 — we see some lights on the runaway there, across the runway. Can you confirm we are clear to land?” the pilot said over the radio to air traffic control.

“Air Canada 759 confirmed to land 28 Right, there is no one on 28R but you,” the tower responded.

The new CTSB report says “the controller was coordinating with another facility” as the Air Canada flight descended.

The tower then ordered the plane to “go around” at the last second.

There were 140 people on the Air Canada flight, and hundreds more on the planes on the ground.

The NTSB is leading the investigation and hopes to speak to that flight crew and the controller in the coming days.

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