The pilots whose 2017 flight very nearly landed atop four loaded airliners waiting in line on a taxiway to take off from San Francisco International Airport, failed to manually tune the airplane’s navigation system for the landing. Had they done so, it may have helped them realize they were off the lateral track for the runway, according to investigators looking into the near disaster.
Tuning the instrument landing system frequency was not a typical procedure for the Air Canada crews. This lapse was one but not the only factor that led the pilots of Flight 759 to get “dangerously close to other airplanes” so that at one point it was at the level of the 66-foot high tails of the two United Boeing 787s waiting in the line. A third United airliner, a Boeing 737 and a Philippine Airlines Airbus A340 widebody were also on the taxiway that pilots mistakenly believed to be Runway 28R.
How the experienced Air Canada pilots confused the dimly lit and fully occupied taxiway with the brightly illuminated runway was the subject of the investigation by the National Transportation Safety Board. At its hearing Tuesday, the board indicated that flight preparation, pilot judgment, perception and fatigue were some of many factors that nearly caused a multi-airplane pileup of record-breaking scale.
“This was a very close call,” Robert Sumwalt, the NTSB’s chairman told those gathered for the public hearing at the board’s headquarters in Washington, DC.
Air Canada Flight 759 was finishing a five-and-a-half-hour flight from Toronto to San Francisco on July 7, 2017. By their body clocks, it was 3:00am for the crew. Runway 28 left had been closed an hour earlier – a fact which had been noted on the crew’s 27-page list of NOTAMS, and transmitted via ACARS during the flight. The Airbus A320 was cleared to land on the parallel Runway which is 28R.
The night was clear and the pilots were making a visual approach over San Francisco Bay. But as the two pilots got closer to the airport, the captain asked the first officer to confirm with air traffic control that the runway was clear. The controller said that it was. There were two controllers working that night, but one was out of the tower at the time and the other was occupied with other business.
The flight continued and as it approached the airport seawall, the pilot of United Flight 1, the first in the line of airliners, saw the plane descending towards him and said over the radio, “Where’s this guy going?”
“The crew sensed something was not right, and they initiated a go-around over the taxiway, avoiding aircraft by very narrow margins,” Sumwalt said. But the near-disaster, which was highly-publicized, prompted the board to take the unusual step of conducting an investigation even though no one was injured and no aircraft was damaged.
Airport surface detection equipment, known as ASDE-X has the capacity to trigger alerts when planes are not lined up over the runway, an enhancement that is being tested at Seattle airport, according to the NTSB investigation.
The NTSB issued seven recommendations including that Canada’s safety authorities review its flight and duty time regulations. The captain of flight 759 would not have been allowed to fly the night of the incident under U.S. rules, the NTSB noted. Transport Canada told investigators it has been trying to update its 22-year old regulations for several years.
The board also issued a general plea to the Federal Aviation Administration to research ways to “more effectively signal a runway closure to pilots during ground and flight operations at night. ”
The safety board did not address the fact that after the plane landed, Air Canada failed to preserve the cockpit voice recorder. The plane was dispatched on further flights so that the information was taped over. It did, however, confirm that the loss of the CVR was detrimental to its investigation. “CVR information, if it had been available, could have provided direct evidence about the events leading to the overflight and the go-around,” the NTSB said.