SINGAPORE - The Civil Aviation Authority of Singapore (CAAS) said in response to media queries that approval had been given for the Surabaya-Singapore sector based on the air rights that were available under the air services deal between both countries and available landing slots at Changi Airport.
Before an airline can launch a service between two points, it needs to obtain approval of its flight schedules from the respective civil aviation authorities at each end of its flight routing separately, the CAAS said.
Indonesia AirAsia had applied to operate a daily flight between Surabaya and Singapore, arriving at Changi Airport at 8.30am and departing for Surabaya at 2.10pm.
The application was made for the period from October 26 to March 28.
CAAS said on Saturday: "These daily flights were approved as there were available air traffic rights under the bilateral air services agreement and the slots at Changi Airport were available."
The airline was operating the flight four times a week on Mondays, Wednesdays, Fridays and Sundays, CAAS said and added: "Airlines may adjust their flight frequencies in the course of a season in response to market demand or operational requirements."
CAAS' reply came after Indonesia's transport ministry said it will investigate all Indonesia AirAsia flight schedules from Monday, an official said, as part of a government investigation into the passenger jet that crashed.
"We are going to investigate all AirAsia flight schedules," Mr Djoko Muratmodjo, acting general director for air navigation in the transport ministry, said on Saturday. "Hopefully we can start on next Monday. We won't focus on licences, just schedules," he added.
"It is possible AirAsia's licence in Indonesia might be revoked," he said, stressing that it was only one possibility.
The transport ministry on Friday temporarily suspended Indonesia AirAsia's Surabaya-Singapore flights because it had apparently operated the service beyond the scope of its licence, which permitted flights on four days of the week but not Sundays, when the crash occurred.
"We will also investigate the party that gave permission to AirAsia to fly on that day," Mr Muratmodjo added.
Indonesia AirAsia chief executive officer Sunu Widyatmoko said the airline would cooperate with the investigation into the Surabaya-Singapore route, but declined to answer further questions.