Air traffic controllers at Newark Airport in New Jersey have lost the radar images for the second time within two weeks.

This means that for 90 critical seconds, they had no knowledge of the position of any aircraft approaching or flying near the airport.

The U.S. Federal Aviation Administration (FAA) specifically reported that the radar in Philadelphia went offline for 90 seconds at 3:55 a.m. on Friday (local time, 10:55 a.m. in Greece).

A similar incident had occurred on April 28.

At that time, hundreds of flights at Newark were canceled or delayed because the FAA had restricted air traffic to ensure flight safety. Several controllers took leave after the incident to cope with the shock from the malfunction, which could have been fatal, according to the Associated Press.

The FAA also announced that it is installing fiber optic cables to more effectively transmit radar signals between its facilities in Philadelphia and New York.