The Department of Transportation’s inspector general has opened an audit into the relocation of the Federal Aviation Administration’s air traffic control facility responsible for flights approaching or departing Newark Liberty International Airport.

It was the first acknowledgment by the Federal Aviation Administration of a possible error by the controller in the moments before the collision that claimed 67 lives.

The acknowledgement came during the second day of testimony held to discuss the collision of a commercial plane and Army helicopter in January that killed 67 people.