The air traffic system meltdown at Newark Liberty International Airport last week “was the most dangerous situation you could have,” according to an air traffic controller on duty that day, as the fallout from the outage stretches into a second week.

A deadly midair collision in January between a military helicopter and a commercial airliner, and several crashes since, have prompted officials to focus on fixing the nation’s outdated air traffic control system and hiring more controllers.

US air safety regulators said they will upgrade equipment guiding flights into Newark Liberty International Airport after a reported radar and radio communications shutdown, endangering travellers and crew flying into the busy hub.