The Federal Aviation Administration is investigating after several airliners on approach to land at Washington Reagan National Airport Saturday morning received what appear to be false alarms from their onboard Traffic Collision Avoidance System.
“It’s been happening all morning. Let me know if you see anything. No one else has seen anything except for on the TCAS,” one air traffic controller can be heard telling an inbound flight, according to ATC audio reviewed by CBS News. At least five flight crews reported receiving apparent false TCAS alerts.
The pilots of American Eagle flight 4469, operated by Republic Airways, were coming into land from Pittsburgh when they received an alert. The flight was descending between 1200 and 1000 feet when TCAS instructed the pilots to take evasive maneuvers to avoid another object.
“We had to dive a little bit,” one of the pilots told air traffic controllers.
Controllers asked the pilots after safely landing, “did you actually visibly see anything other than what the TCAS was showing?”
“Negative, it would just say an unknown target descending rapidly,” the pilots responded.
“Alright, that’s the same sort of reports we’ve been getting. It seemed like it had stopped but it sounds like it’s starting again,” a controller replied.
Former chair of the National Transportation Safety Board and CBS News transportation safety analyst Robert Sumwalt said that the situation is unusual.
“I’ve never heard of something like this,” the retired 737 captain said. “Nuisance alerts, yes, they happen. But not like this where several planes have it at the same location.”
The FAA said in a statement to CBS News that several flight crews inbound to Reagan National Airport reported the onboard alerts when no other aircraft were nearby, but the total number of aircraft impacted is unclear.
The TCAS is a piece of technology installed on individual planes, not a ground-based or centrally located system. It works by using an aircraft’s transponder to detect and communicate with nearby aircraft. After receiving the position and altitude of the nearby aircraft, the system calculates if there’s a potential for collision. If it finds there’s a potential, it will instruct the pilots via audible alerts and displayed instructions to watch for traffic, climb or descend to avoid a mid-air collision.
“Some of the crews executed go-arounds as a result of the alerts. The FAA is investigating why the alerts occurred,” the FAA’s statement said.
Federal investigators on Monday added that the issue has not been reported again since Saturday morning, with last reports coming in around 9 a.m. EST.
“Yeah, we got a little something there,” the pilots of American Eagle flight 4538, also operated by Republic, from New York City’s John F. Kennedy International Airport said after they received a similar alarm on Saturday morning. “It said on the TCAS, it was 600 feet above us and we didn’t see anything.”
American Eagle flight 5197 arriving from Minneapolis reported the same thing occurring on their approach: “We got a TCAS but we didn’t see anything either.”
Arriving from Des Moines, American Eagle 5098 reported receiving two warnings.
Flight 5802 from Nashville told controllers after an alert, “we saw nothing out there though.”
The crew of Flight 4469 appeared to joke about a possible explanation, saying it was “aliens.” Another voice said “Russia.”
The incidents unfolded amid heightened scrutiny at Reagan National Airport after January’s deadly crash between a Black Hawk and a regional aircraft. Last month, the NTSB recovered the plane’s TCAS and investigators are working to examine the system and related components.
