As Air Canada flight number 759 was preparing to land at San Francisco International Airport (SFO) in 2017, it mistook one of the airport's taxiways for the runway. It could have been a major disaster if the experienced Air Canada pilots had not aborted the landing at the last minute.

To set the scene, on July 7, 2017, Air Canada flight 759 was arriving in San Francisco after a late-night flight from Toronto Pearson International Airport (YYZ). The aircraft, a 24-year-old Airbus A320-200 carrying 135 passengers and five crew, had been cleared by air traffic control to land on runway 28R.

The pilots mistook a taxiway for the runway

Instead of lining up to land on runway 28R, the Air Canada pilots were going to land on an adjacent taxiway where four other aircraft were waiting for permission to take off. As the plane was on final approach, the Air Canada pilots saw what they thought were lights on the runway and asked the tower to confirm that the runway was clear.

Runway 28R and Taxiway C at SFO.
The Air Canada A320-200 was going to land on the taxiway. Image: Mliu92 via Wikimedia

The controllers in the tower assured them that it was and that they were clear to land. At the exact moment, a United Airlines pilot in one of the planes waiting to take off radioed the tower saying, "Where's this guy going?" Then three seconds later: "He's on the taxiway."

It could have been worse than Tenerife

As the First Officer of the Air Canada flight glanced out of the window, he did not think things looked right and shouted, "go around, go around." The Captain complied and climbed out of the approach. The Canadians did not know that they were just feet away from four fully fueled jets waiting to take off. Had they not aborted the approach, it could have been a disaster more extensive than the Tenerife accident in 1977, in which 583 people were killed when two Boeing 747s collided.

As the plane was landing at SFO it was midnight local time but 3 am in Toronto. Image: GCmaps

During a National Transportation Safety Board (NTSB) investigation into the near-miss pilots who had landed a few minutes before the Air Canada flight confirmed that construction lights were so bright that they could not visually determine the inbound runway and referred to instrument readings. A captain of one of the earlier flights told the NTSB that the planes parked with their taxi lights off helped make taxiway C look like the runway.

Stay informed: Sign up for our daily and weekly aviation news digests.

Fatigue could have played a part

In its final report on the incident, the NTSB criticized Canada's pilot fatigue rules. Despite both pilots being highly experienced, it was 03:00 in the morning Toronto time when the plane was landing. The First Officer had taken no rest for 12 hours and the Captain for 19 hours. According to US pilot fatigue rules, the Captain's lack of sleep would not have prevented him from flying. Transport Canada later changed its rules on pilot rest to bring them closer to international standards.

Following the close call, the Federal Aviation Administration (FAA) banned all visual night approaches into SFO when the airport's parallel runway was closed, as was the case on the night of the near-miss. The FAA also said that two controllers must be in the tower to handle late night flights, and while this was the case with Air Canada flight 759, only one of the controllers was in the tower.