The nation’s air traffic controllers union says the flight cancellations plaguing Newark Liberty International Airport in new Jersey and spilling over to U.S. airports can be traced to a week ago when controllers temporarily lost contact with planes.

At least five air traffic controllers have taken 45-day trauma leave, per CNN, suggesting delays at Newark, which averaged two-hours-and-forty minutes on Monday, will endure for some time. Any delays will be exacerbated by the renovation to one of Newark’s runways, which will continue until June 15.