Federal authorities are investigating a close call this week involving a military helicopter and a United Airlines plane approaching John Wayne Airport in Santa Ana.

United Airlines Flight 589 was approaching the airport in Orange County around 8:40 p.m. Tuesday when a Sikorsky Black Hawk helicopter crossed its path, according to the Federal Aviation Administration.

Pilots on the United Airlines plane were advised by air traffic control to watch for the military helicopter flying near the airport, United Airlines said.

“They saw the helicopter, and also received a traffic alert, which they responded to by leveling the aircraft,” United said.

The United flight with 162 passengers and six crew members landed safely.

The new investigation comes a week after the FAA issued a new airport safety order designed to improve safety near airports where helicopters cross both arrival and departure paths. The order suspends use of visual separation between airplanes and helicopters and requires air traffic controllers to use radar to manage lateral and vertical separation between aircraft.

A close call earlier this month between a twin-engine Beechcraft 99 and helicopter at Hollywood Burbank Airport was cited by federal authorities as a key factor behind a new airport safety measure.

In another example, the agency said American Airlines Flight 1657 was cleared to land at San Antonio International Airport when a police helicopter was on its final approach path. The helicopter turned to avoid the American Airlines plane, the FAA said.

The new requirement applies to more than 150 of the nation’s busiest airports and extends a restriction already in place at Ronald Reagan Washington National Airport.

The upgraded safety measure was rolled out after a year-long FAA safety team review. In a news release, the FAA also referenced the Jan. 29 American Airlines jet and Army Black Hawk crash that killed 67 people. A key factor in the crash was the placement of a helicopter route in the approach path of Reagan National Airport’s secondary runway, the NTSB board said, also identifying air traffic controllers’ over reliance on asking helicopter pilots to avoid other aircraft as a factor.