Planes receive mysterious false midair collision alerts near Reagan National Airport

Reagan National Airport is seen here in January 2025. Andrew Harnik/Getty Images via CNN Newsource

The Federal Aviation Administration is investigating why multiple commercial flights about to land at Ronald Reagan National Airport, near Washington DC, repeatedly received midair collision alerts over the weekend when there were no other aircraft nearby.

The alerts occurred only miles from the site of the deadly January 29 midair collision of American Eagle 5342 and a US Army Blackhawk helicopter.

Several flight crews reported the mystery alerts on their Traffic Collision Avoidance System, known as TCAS, on Saturday “indicating another aircraft was nearby when no other aircraft were in the area,” the FAA said in a statement on Monday.

“We were about 1200 feet, there was somebody diving straight onto us,” a Republic Airline pilot told the control tower just after 9 a.m. Saturday according to audio captured by LiveATC.net.

“It’s been happening all morning. Let me know if you see anything. No one else has seen anything except for on the TCAS,” the tower air traffic controller warned another Republic flight coming in to land.

“Yeah, we got a little something there,” the pilot responded a short time later. “It said on the TCAS that it was 600 feet above us. And we didn’t see anything.”

TCAS works independently of ground air traffic control, searching nearby airspace using radio frequencies from transponders in other aircraft. If it detects a potential collision the system gives pilots specific maneuvers to safely get away.

Low altitudes and landing approaches can cause problems with the system and since it uses radio signals there can be interference, but it’s uncommon for so many planes received the false warnings in such a short period of time.

“Reporting traffic around our 11 o’clock. We got anything out here,” a PSA Airlines pilot questioned the control tower Saturday. “Negative… no known traffic between you and the field.”

The FAA says some pilots elected to abort their landings, known as a go-round, “as a result of the alerts.”