The incident occurred when the aircraft was still in the maintenance area, at Bay 48. “It’s a leased aircraft and not owned by Air India,” said an Air India spokesperson. “Prima facie, the nose gear seems to have collapsed but the plane was still in the maintenance area while designated to fly to Dubai.” He said nobody was injured in the incident.

On Thursday, the door of an Airbus A-320 was damaged after the still-attached aerobridge slammed against it as the pushback vehicle at the rear wheels began to move. The passengers had already boarded.

It is standard procedure for engineers to carry out maintenance tests on a departing plane. Sources said the plane's landing lever was put into the ‘retract’ position forcing the front wheel of the plane to collapse while it was still standing. The landing lever is put into this position once the aircraft hits airspace, allowing the wheels of the plane to retract into the aircraft.

“Prima facie, it appears to be a case of human error as the ground engineer should have fixed the nose pin on top of the front wheel before testing the landing lever,” said an air safety expert, not wishing to be named. The nose pin is a thick titanium pin that fixed on top of the front wheel of the aircraft so that even when the lever is ‘retracted’, the front wheel cannot collapse.

While an aircraft engineer named Panchal was testing the plane from the cockpit, it was ground engineer Manoj Nair, under its belly, who reportedly saw the plane vibrating violently. He escaped unhurt, narrowly. The Dubai-bound plane, the AI 717, is a Boeing 777 and among the new aircraft in Air India's stable, leased from the United Airlines. The airline spokesperson said while human error could not be ruled out, the two engineers concerned have been suspended pending an inquiry. He also refuted charges of the aircraft had vibrated before its nose collapsed, saying no aircraft can vibrate when its engine is switched off.

“While nothing can be said before investigations are completed as you have to carefully go through every minute detail. However, you cannot ignore the fact that it is a very serious incident -- there is no doubt about that,” said senior civil aviation advisor and a former Director of Civil Aviation, H S Khola.