WASHINGTON, March 26 (Reuters) - The Federal Aviation

Administration said on Thursday it was investigating a close

call between a United Airlines jet and an Army Black Hawk

helicopter in California.

The FAA said the United Boeing 737 jet on Tuesday at 8:40

p.m. was on approach to John Wayne Airport in Orange County,

California, and a Black Hawk crossed in front of the plane.

Flightradar24, a flight tracking site, said the aircraft were

525 feet apart vertically.

The FAA is also investigating whether the incident violated

its new policy that bars visual separation for helicopters near

major airports.