Bomb Threat Against United Flight Grounds Planes at Reagan Airport, Hear Audio

Flights to and from Reagan National Airport in Washington, D.C. were put on a temporary hold Tuesday after a bomb threat was made against a United Airlines flight ... and you can listen to the air traffic controller warning the pilot.

Check out the clip -- the air traffic controller informs the cockpit they've got an "unconfirmed bomb report" and mandates they land on a runway away from the main airport structure.

United States Secretary of Transportation Sean Duffy said on X the flight landed safely at DCA and passengers were evacuated so law enforcement could carry out a full search of the aircraft.

Reagan confirmed runways opened back up less than 2 hours after the UA flight landed and Metropolitan Washington Airports Authority police investigated with multiple partners.

The FAA tells TMZ ... United Airlines Flight 512 had just landed from George Bush Intercontinental Airport in Houston. The FAA said there was a reported "security issue" on the aircraft and that passengers deplaned onto the taxiway, as authorities swept the plane.

During the investigation, several flights were diverted to other airports ... and the airport warned passengers they could expect delays resulting from the incident.

Luckily, the reported threat was a bunch of bologna ... and Duffy thanked authorities for their quick response. Regular operations resumed Tuesday afternoon.

As you know, the threat came as the government continues its shutdown -- with air traffic controllers among those who must work without pay ... one of many reasons why TMZ's Harvey Levin has been pushing for the "Out With Their Asses" movement.