SURABAYA - Indonesia is probing all airlines to see if they are violating terms of their route permits after the transportation ministry said AirAsia Indonesia was not authorised to fly to Singapore on Dec 28, the day its jetliner crashed into the Java Sea, Bloomberg reported on Sunday.
AirAsia "clearly" breached its route permit as it wasn't permitted to fly from Surabaya to Singapore on Sundays, the day the accident occurred, Mr Djoko Murjatmodjo, director-general for air aviation at the transportation ministry, was quoted by Bloomberg as saying.
The ministry is checking other carriers to ensure they comply with all rules, Murjatmodjo told the news agency.
AirAsia Indonesia was only permitted to fly between the two cities on Mondays, Tuesdays, Thursdays and Saturdays, according to Indonesia's transport ministry.
"We're investigating all other airlines to see if the same thing is happening there," Murjatmodjo said. "It's their responsibility to follow what we permit them to do."
The ministry has grounded AirAsia for the Surabaya-Singapore route since Friday, and the suspension will stay until the National Transportation Safety Committee (KNKT) completes its investigation into the alleged breach.
Former Indonesian Air Force chief of staff and aviation observer Chappy Hakim told Indonesia media he "did not understand" the alleged violation.
"If it's proven that AirAsia flew on a day it wasn't supposed to fly, the question is how could its flight plan be approved in the first place?" Chappy said on Saturday as quoted by kompas.com.
"It makes little sense that they chose to fly on a Sunday knowing they didn't have permission to do so."
He added that it was very odd for an unauthorised flight to have gone ahead.
AirAsia Indonesia's communication manager Malinda Yasmin said the airline could not provide any information before the investigation was completed.
"We will cooperate with the government during the investigation process," she told The Jakarta Post via SMS.