The National Transportation Safety Board determined Tuesday an Air Canada flight crew’s lack of awareness caused the July 7, 2017, overflight of a taxiway at San Francisco International Airport.

Air Canada flight 759 was cleared to land on runway 28R but instead lined up with parallel taxiway C where four airplanes were awaiting clearance to take off. Flight 759 descended to an altitude of 100 feet above ground level and overflew the first of the four airplanes. The flight crew initiated a go-around, and flight 759 reached a minimum altitude of about 60 feet above ground level and overflew the second airplane before starting to climb.

The NTSB said in its report the misidentification of taxiway C—as the intended landing runway—resulted from the flight crew’s lack of awareness of the runway 28L closure due to their ineffective review of the notice to airmen information before the flight and during the approach briefing. Although the notice to airmen about the runway 28L closure appeared in the flight release and the aircraft communication addressing and reporting system message provided to the flight crew, the presentation of that information did not effectively convey the importance of the runway closure information and did not promote flight crew review and retention.

“The mistakes identified in this report highlight the need for further review of approach and landing procedures,” says NTSB chairman Robert L. Sumwalt, in a release. “This event could very easily have had a catastrophic outcome. The recommendations issued as a result of this investigation, if implemented, will help prevent the possibility of a similar incident from occurring in the future.”

The probable cause cited fatigue as a contributing factor in the incident. While the flight crew’s work schedule for the incident flight complied with Canadian flight time limitations and rest requirements, the flight and duty-time and rest requirements for the captain would not have complied with US flight-time limitations and rest requirements.

As result of the investigation the NTSB issued six safety recommendations to the Federal Aviation Administration and one to Transport Canada. The recommendations address issues including the need for airplanes landing at primary airports within class B and class C airspace to be equipped with a system that alerts pilots when an airplane is not aligned with a runway surface, more effective presentation of flight operations information to optimize pilot review and retention of relevant information, a method to more effectively signal a runway closure to pilots when at least one parallel runway remains in use, and modifications to airport surface detection equipment systems to detect potential taxiway landings and provide alerts to air traffic controllers.

The abstract of the report includes the findings, probable cause, and all recommendations. The docket material for the Air Canada incident investigation contains factual reports for operations, human performance, air traffic control, aircraft performance, airport, and the flight data recorder. The docket also contains a video that shows the overflight, as well as interview summaries, photographs, and other investigative material.

The full report will be available on the NTSB website in several weeks.