Two United Airlines planes clipped wings at San Francisco International Airport early Tuesday morning while preparing for take off, according to the Federal Aviation Administration.

The incident occurred "in an area where air traffic controllers do not communicate with flight crews," the FAA said in a statement shared with PEOPLE

In a statement, the Federal Aviation Administration said United Flight 863 heading to Sydney, Australia and United Flight 877 bound for Hong Kong were the two planes involved. Flight 863’s left wingtip collided with the right wingtip of Flight 877 about 12:35 a.m., the FAA said.