The Federal Aviation Administration is investigating after two flights had to abort landings at Reagan Washington National Airport on Thursday because of a U.S. military helicopter en route to the Pentagon.
Delta Air Lines Flight 1671 and Republic Airways Flight 5825 were instructed to perform go-arounds due to the military helicopter in the vicinity.
The FAA had imposed restrictions on non-essential helicopter operations near the airport following a tragic mid-air collision on January 29.
Both airlines, Delta and Republic, are cooperating with the FAA investigation.
The airport's proximity to Washington, D.C., has made it popular with lawmakers, tourists, and residents.
The FAA has implemented changes to address safety concerns at the airport, including restrictions on helicopter traffic.
Recent safety incidents have prompted calls for stricter requirements for helicopters near DCA.
The FAA is also investigating helicopter traffic near other major airports to ensure safety.
Contributing: Zach Wichter, USA TODAY