An Air Canada flight with 140 passengers onboard came within 100 feet of causing what could have been one of the worst disasters in aviation history.

Last Friday, Air Canada Flight 759 was forced to abort a landing at San Francisco International Airport (SFO) and perform a go-around after the pilot “inadvertently” attempted to land on a busy taxiway.

The incident happened at around 11:56 p.m. At the time, four planes were sitting on the taxiway waiting to take off.

Transportation Safety Board of Canada (TSB) issued a preliminary report yesterday on the Air Canada near-miss at SFO. The report indicates that the Air Canada pilot flew over the taxiway for about a quarter of a mile before anyone noticed. The flight came within 100 feet of hitting two planes on the ground. A third plane was missed by 200 feet and a fourth by 300 feet, per the report. All of the flights were packed with passengers.


How Did the Air Canada Near Miss at SFO Happen?

According to the TSB preliminary report, Air Canada 759 was making a visual approach to SFO Runway 28R. When the plane was just over a half mile from the runway threshold, the pilots asked air traffic controllers (ATC) to confirm their landing clearance at Runway 28R because they were seeing lights.

ATC confirmed that the flight was clear to land at Runway 28R. The controller was coordinating with another facility when a flight crewmember from a flight on the taxiway stated that Air Canada Flight 759 appeared to be lined up with Taxiway C, which runs parallel to Runway 28R. ATC immediately instructed the Air Canada flight to perform a go-around. By that point, however, the plane had already overflown Taxiway C for approximately a quarter of a mile.

The TSB report also noted that at the time of the incident, there was only one air traffic controller handling ground and tower frequencies. The controller handling the approach was also busy coordinating with another facility at the time of the near-miss, according to the report.

“Looking at the time of the incident, the first question we need to answer is whether the pilot was fatigued,” says Ilyas Akbari, an aviation attorney at Baum, Hedlund, Arsitei & Goldman. “We don’t talk about fatigue in aviation often enough, but it has been a contributing factor in a surprising number of disasters.”

Akbari also said pilot training could be a factor in the Air Canada incident, just as it was in the last major incident at SFO—the crash of Asiana Airlines Flight 214. On July 6, 2013, a Boeing 777 operating as Asiana Flight 214 collided with a seawall just short of a Runway 28L and crashed. Three passengers died and over 180 others sustained injuries in the incident.

The Asiana pilot at the controls, Lee Kang Kuk, was a trainee in the Boeing 777, and had not landed a plane at SFO for nearly a decade. He told investigators he was “very concerned” making the approach to land at SFO.

“The fact that the pilot was stressed and nervous is a testament to the inadequate training he received, and those responsible for his training and for certifying his competency bear some of the culpability for the tragedy of this crash,” said Akbari back in 2013.

Akbari’s firm has settled 24 passenger claims arising out of the Asiana crash and has one passenger case remaining. That case is set to go to trial September 22, 2017.