WASHINGTON, May 2 (Reuters) - Two flights aborted

landings at Reagan Washington National Airport on Thursday

because of the presence of a U.S. military helicopter that was

headed to the Pentagon, the Federal Aviation Administration

said.

The FAA, which is investigating the incident, said Friday

air traffic control instructed Delta Air Lines Flight 1671 and

Republic Airways Flight 5825 to perform go-arounds due to a

priority air transport helicopter.

In the aftermath of a January 29 mid-air collision of an

American Airlines ( AAL ) regional jet and an Army helicopter

that killed 67 people, the FAA imposed permanent restrictions on

non-essential helicopter operations around Washington's Reagan

National Airport.