An Air Canada plane almost crashed into four other planes on the ground, possibly evading history’s greatest aviation disaster.

Air traffic control cleared an Airbus A320 flying in from Toronto to San Francisco’s International Airport. Rather than landing on the clear runway, however, the pilot lined up to land on a parallel taxiway. Four planes full of passengers and jet fuel were on that taxiway.

This incident occurred just before midnight on Friday.

Audio records show there seems to have been some miscommunication between the pilot and the air traffic control tower. The pilot asked for confirmation to land across the runway. The control tower responded; “confirmed to land on runway 28-Right, there is no one on 28-Right but you”.

The tower had no idea that the pilot was not at all lined up to land at that runway. Rather, the pilot was about to land at Taxiway C which was right next to it.

The control tower responded quickly, and managed to avert a catastrophic accident when they redirected the plane. The plane just managed to evade the landing at 400 feet, missing two aircraft on the ground by approximately 100 feet. A320s can carry as many as 220 passengers. Air Canada commented this particular flight was carrying 135 passengers and five crew members.

One retired pilot, now CEO of Aero Consulting Experts, commented: “If it is true, what happened probably came close to the greatest aviation disaster in history. If you could imagine an Airbus colliding with four passenger aircraft wide bodies, full of fuel and passengers, then you can imagine how horrific this could have been.”

About half a minute after the plane evaded, a pilot on a United Airlines plane on the taxiway said the jet “flew directly over us“. The aircraft proceeded to land in a normal fashion about 15 minutes later.

Air Canada and the U.S. Federal Aviation Administration are currently investigating the details of what occurred last week