Two large aircraft were involved in a minor collision at Changi Airport early yesterday, delaying the journeys of more than 600 passengers who were on board.
Nobody was injured, but the Airbus 380 and Boeing 787, which hit each other wing to wing, have been grounded for repairs.
Following the incident, which occurred at about 1.40am between an Emirates A-380 and Scoot B-787, Changi Airport Group has issued a safety notice to all airlines, ground handlers and other partners.
The incident occurred when Emirates Flight EK405, bound for Dubai, was being pushed out of gate C23 at Terminal 1 by a tow tug.
The Scoot aircraft, controlled by the pilot, was meanwhile taxiing to prepare for departure to Tianjin, China.
The Emirates plane was reversing towards the left when its right winglet came into contact with the left wing of the Scoot aircraft which was heading straight, The Straits Times understands.
The Civil Aviation Authority of Singapore and Changi Airport Group said they are working with the relevant parties to investigate the incident.
Experts said the probe will likely focus on instructions that were given by air traffic control and whether the Scoot pilot had kept a proper lookout.
"In this case, it would seem that the Emirates pilot is clear since the plane was being pushed back and he was not in control of the aircraft at the time," said a source who did not want to be identified.
A Scoot spokesman said all 303 passengers were put on a replacement aircraft, which departed at about 6am - more than four hours after the incident.
Mr Raymond Tham, chief executive and managing director of a Tianjin-based pharmaceutical online website who was on the Scoot flight, said: "I did not hear or notice anything. Neither did the passengers make an exclamation or commotion about the collision.
"We were stationary for a while before the pilot made an announcement, which mentioned something about damage to a wing and the need to return to a gate, but without any specifics."
There was little information provided during the four-hour wait for the replacement plane, and passengers were also not served any refreshments, he added.
All passengers on the Emirates aircraft were rebooked on alternative flights, a spokesman said, so that the aircraft which was "slightly damaged" could be repaired.
The last reported case of planes hitting each other at Changi Airport was in June last year, when the tail cone of an SIA plane that was parked was damaged after it was hit by the wing of another SIA aircraft that was being towed.
Ground accidents on the tarmac, including baggage vehicles and aerobridges that hit stationary planes, are a growing concern for the International Air Transport Association (Iata) as flight numbers increase and airports become more crowded.
To reduce the number of such incidents, Iata, which represents global carriers, has in the past few years been encouraging sharing of information for learning purposes.
Airports are also increasingly turning to automated tarmac vehicles to mitigate the risk of human fatigue causing accidents.
At Changi Airport, automated airside vehicle trials are currently being carried out.