Jersey Airport radar fault affects about 40 flights
About 40 flights were delayed after interruptions to Jersey Airport's radar service on Monday.
No commercial flights were cancelled but the airport had to stay open late to clear the backlog.
The airport moved its air traffic service to a contingency facility in the north of the island to allow some flights to operate.
Flights started to return to normal at about 18:30 GMT when air traffic services returned to the airport.
Jersey normally handles all Channel Island air traffic control, but Guernsey took back control of their own airspace while the radar issues were resolved.
Jersey Airport's chief operating officer for aviation, Stephen Driscoll, said a full internal investigation would now take place to find out why the radar stopped sending data.
He said: "Although radar services at Guernsey Airport were not lost, allowing them to operate inter-island flights to and from Alderney, as they are included in the Channel Islands Control Zone, flights in and out of the Bailiwick were also affected."
Mr Driscoll said: "The safety of aircraft and passengers was not compromised at any time."