When the agency approved moving Newark air traffic controllers to Philadelphia, it said the odds of a dangerous communications breakdown was about 1 in 11 million.

An experienced air traffic controller retired just days after his radar failed as planes flew into New York airspace, according to The New York Times. The fault meant the Philadelphia-based Newark Liberty International Airport controller lost radar imagery for around a minute and a half on Aug.

Prompted by a radar failure a week ago at Newark Liberty Airport, and a midair collision that killed 67 people in Washington D.C., President Donald Trump‘s administration announced an unprecedented program to rebuild the nation’s air traffic control system and recruit more air traffic controllers.