A United Airlines Boeing 777 jet clipped the wingtip of another United plane while it was pushing back from the gate early Tuesday morning at San Francisco International Airport, prompting the cancellation of two trans-Pacific flights that had been carrying more than 500 passengers between them, officials said.

No one was injured during the mishap, the latest incident to bring scrutiny to commercial aviation safety procedures in the United States.

The brush between the two planes occurred around 12:35 a.m., according to the Federal Aviation Administration, which said that the planes were maneuvering in an area where air traffic controllers do not communicate with flight crews.

As one of the Boeing 777s was leaving the gate to fly to Sydney, Australia, its right wingtip clipped the left wingtip of a flight departing for Hong Kong, the F.A.A. said in a statement. A video that appeared to have been taken from inside one of the airport’s terminals showed workers standing on a hydraulic lift inspecting the point where the two wings clipped.

A spokesman for the airport referred questions on the incident to United Airlines.

There were 202 people and 16 crew members on the flight to Sydney, while the plane to Hong Kong had 306 passengers and 16 crew members on it, according to the airline. United did not say what kind of damage the planes had sustained or what had led to the accident.

United said that it was working to rebook the passengers on other flights.

The mishap happened at a time of increased anxiety about commercial aviation in the United States, following other accidents, disruptions and flight-path problems and a week after air traffic controllers briefly lost communication with planes at Newark Liberty International Airport, their union said. The communications breakdown at Newark prompted hundreds of delays and cancellations, in addition to dozens of flight diversions. United said last week that it was cutting back its daily flight schedule at Newark, citing a shortage in air traffic controllers.

Last month, two American Airlines jets, including one carrying at least six members of Congress from New York and New Jersey, clipped wings on a taxiway at Ronald Reagan National Airport outside Washington.

No one was injured in that incident, but it brought fresh scrutiny to safety at the airport, where an American Airlines regional jet making its final approach was struck by an Army helicopter on Jan. 29, killing all 67 people aboard the two aircraft. That crash was the deadliest in the United States in 20 years.

On Thursday, air traffic controllers instructed two commercial flights to abort their landings at Reagan Airport because an U.S. Army helicopter was preparing to land nearby at the Pentagon, said the F.A.A., which added that it was investigating.

Soon after those aborted flights, the Army said that it was suspending training flights around the Pentagon, Reuters reported.