The Federal Aviation Administration (FAA) is investigating why multiple commercial flights approaching Ronald Reagan National Airport near Washington D.C. received midair collision alerts over the weekend, despite there being no other aircraft nearby.
The alerts, which were triggered on Saturday, occurred only miles away from the location of the deadly midair collision on January 29 involving American Eagle flight 5342 and a US Army Blackhawk helicopter.
Several flight crews reported the mystery alerts on their Traffic Collision Avoidance System (TCAS), which indicated the presence of another aircraft even though none were in the area.
One Republic Airline pilot described the incident on the control tower audio, saying, “We were about 1200 feet, there was somebody diving straight onto us.” The pilot also mentioned that the TCAS was showing conflicting information, as no other aircraft could be seen.
The TCAS system works independently from ground control by detecting nearby aircraft using radio signals from their transponders. If a potential collision is detected, the system suggests maneuvers for pilots to avoid danger.
Low altitudes and landing approaches can cause problems for the system, and interference from radio signals can occasionally lead to false alerts. However, it is rare for so many flights to experience these false alarms in such a short time.
The FAA confirmed that some pilots chose to abort their landings after receiving the alerts, a procedure known as a “go-around,” due to the warnings.