It was disaster averted by less than two minutes.

Initial investigations have revealed that the May 26 Air India Express Dubai-Pune flight IX-212 was less than two minutes away from plunging into the Arabian Sea. It had plummeted dangerously from an altitude of 37,000 feet when its commander was away from the cockpit, in the washroom, leaving the first officer to man the controls. The aircraft's nose was down to a minus-23-degree angle because of which its descent rate increased rapidly and went up to 21,000 feet per minute even as the overspeed warning blared loudly in the cockpit.

That was the scene the commander walked into after his loo break. A few minutes before that, the Boeing 737 had entered Indian air space and was cruising over the Arabian Sea. The airplane was on autopilot at 37,000 feet when the commander handed it over to the first officer and walked out closing the cockpit door behind him. According to sources, the commander realized something was wrong when he returned from the washroom and did not get any response after he pressed the cockpit's door-unlock button (it sets off a chime inside the cockpit and the pilot sitting inside responds by pushing a button which opens the door). By this time the commander also realized that the aircraft was at an unusual pitch attitude (a pitching movement is nose up-nose down motion of an aircraft and a nose-down pitch increases air speed). Sensing danger, the commander punched in the emergency code, which opens the cockpit door, but only after 35 seconds.

"On entering the cockpit, he was shocked when he saw the Primary Flight Display, which displays information on altitude, vertical speed (in this case rate of descent) and the air speed. It showed the aircraft's nose was down by minus 23 degrees, due to which it was flying at 0.88 Mach," said the source. Mach One is the speed of sound and therefore 0.88 Mach is 88% the speed of sound, which was well beyond the operating limit speed of most passenger aircraft. The loud aural alarm or the clacker, in aviation parlance, which blares continuously giving an overspeed warning was on. "Such a high speed could lead to structural failure of the aircraft and to recover from such a situation safely requires exceptional pilot skills," he said adding that the commander appeared to have displayed remarkable skill in following the textbook "jet upset recovery procedure".

The incident puts a huge question mark on the training given by Air India Express, especially to its first officers. The first officer had 1,000 hours of flying experience on the Boeing 737 aircraft which, say aviation safety experts, is quite adequate to handle a situation like this.

The Directorate-General of Civil Aviation (DGCA) is investigating the incident. "The aircraft plunged at speeds beyond its maximum limit. The recovery would have stressed the structure abnormally. This would require special investigations to be carried out on the aircraft after landing," said an air safety expert. It was not known whether the aircraft was grounded following this incident.