The Federal Aviation Administration says that the Southwest plane cleared the runways while the other planes passed overhead and that a decision to abort the landings was “precautionary.”
An air traffic controller at the airport told the Southwest pilots they should not have been on the runways during the 19 May incident, according to The Associated Press.
Officials say that an inbound United Airlines plane was as low as a few hundred feet over San Francisco Bay before its pilots saw the Southwest jet on the same runway.
A short time later, pilots of an inbound Alaska Airlines plane saw the same Southwest jet crossing a second, parallel runway, and the pilots aborted their landing as well.
Both planes circled and landed safely at the waterfront airport, which is the second busiest in California after LAX in Los Angeles.
An air traffic controller told the crew of the Southwest jet, “You shouldn’t be on the runway,” according to a recording of the incident on LiveATC.com.
And when one of the pilots tried to explain why they were there, the controller quickly cut them off, saying, “I don’t need an argument.”
“The FAA looked into the events and determined the appropriate steps were taken to ensure safe operations,” the agency said in a statement.
The National Transportation Safety Board said it has not opened an investigation into the incident.
The FAA says that there has not been a fatal crash involving a US airline since 2009.