Indonesian transport authorities suspended aviation officers Monday who were on duty at the time of AirAsia Flight 8501’s crash as a probe into the incident continues. The doomed AirAsia flight was apparently unauthorized, and authorities have threatened to revoke airlines’ licenses should any domestic carriers violate their flying permits in the future.

Djoko Murjatmodjo, acting director-general of civil aviation, said the Transport Ministry has ordered the air traffic controllers, airport operator and airport aviation officers on duty at the Surabaya airport on Dec. 28 suspended, according to the Wall Street Journal.

The Transport Ministry said it will also hold airlines to greater accountability in the future. "If, after assessment, another airline is also not flying on the approved schedule, that is a violation and we will suspend it, too," Murjatmodjo told reporters, according to Channel News Asia. The AirAsia flight, which was apparently authorized to fly only on Mondays, Tuesday, Thursdays, and Saturdays, flew on a Sunday, and investigations are under way into who might have greenlighted the plane’s takeoff. AirAsia Indonesia, the domestic operator of Malaysia-based AirAsia, has already had its Surabaya-Singapore flight permits suspended.

National Police Chief Gen. Sutarman has also said he will lend his manpower to the National Transportation Safety Committee’s and the Transport Ministry’s probe into possible violations of aviation law.

Following the AirAsia crash on Dec. 28 on its Surabaya-to-Singapore flight, Indonesia’s Transport Ministry launched a revision of air safety protocols. All pilots are now required to attend a briefing with flight operating officers (FOO) prior to takeoff after it was reported that the pilot on Flight 8501 took weather information reported by the meteorological agency BMKG, rather than through the airlines, according to the Wall Street Journal. While many airlines in Indonesia currently do perform direct briefings with their pilots, it was not a formal requirement. Murjatmodjo said that the FOO briefings will not only cover weather conditions, but the FOO will also be able to assess if the pilot is in good health to perform the flight.

Didit Soerjadi, operations manager with Indonesia’s chartered flight operator PT Gatari Air Service, told the Wall Street Journal that as FOOs need to be hired, airliners’ operational costs will increase, and acknowledged that some pilots just check on weather conditions themselves. “Can you imagine what will happen if an airline company has 15 flights from a certain airport at the same time and all pilots must be briefed?” he said.