A Singapore aircraft with a pilot instructor and two trainees on board landed safely at Seletar Airport at 7.18pm yesterday, about 30 hours after it was intercepted by Indonesian fighter jets on Tuesday.
The C90GTi King Air plane owned by Singapore Technologies (ST) Aerospace and operated by its pilot training arm, Pacific Flight Services, left Pontianak in West Kalimantan at about 5.30pm Singapore time.
The plane, which was carrying a Singaporean pilot and two foreigners - believed to be Chinese nationals - was forced to land in Pontianak after being intercepted by two Indonesian Air Force Sukhoi 27/30 Flanker jets.
It was en route from Sibu in Sarawak to Singapore and allegedly flying in Indonesia's airspace without the necessary approvals.
ST Aerospace has insisted that it followed protocol.
A spokesman told The Straits Times last night: "The company had filed the original flight plans as it normally has done for similar flights."
The incident occurred during a return route familiarisation training flight as the instructor and pilot trainees were passing through a portion of Indonesian airspace which was in the filed flight plan, the spokesman said.
ST Aerospace is currently seeking clarification with the authorities on this matter and will make changes to the flight plan filings as required, she said.
Industry experts say the norm is for aircraft operators to file their flight plans through the civil aviation regulator of the country from which they depart.
The information is then conveyed to the authorities overseeing the skies along the path.
In this case, the flight plan was filed with the Civil Aviation Authority of Singapore before departure from Seletar and with the Malaysian authorities before the plane left Sibu.
The Indonesian Air Force has said that although the plane was overflying airspace managed by Singapore air traffic controllers, it was inside Indonesia's sovereign skies. As such, the flight needed approval from the Indonesian authorities, which was allegedly not obtained.
Tuesday's interception was the second such incident in a week.
On Oct 22, the Indonesian Air Force forced an Australian private jet flying from Darwin to Cebu in the Philippines to land in Manado, North Sulawesi, for an alleged similar offence.
Commenting on the ST Aerospace incident, the commander of the Indonesian Armed Forces, General Moeldoko, who was in Singapore on a three-day visit which ended yesterday, said: "Interception is an SOP (standard operating procedure) we adopt when an aircraft enters our sovereign airspace (unannounced).
"I believe all countries have common procedures for this, as they do (for intrusions) on land or at sea. Such stern measures are accepted by all countries, and this is our position."