A probe will establish the reason for drop in cabin pressure that left dozens of passengers bleeding through nose and ear onboard a Jet Airways flight, but experts are not ruling out possibilities other than pilot error.

In case there is malfunction in aircraft systems or defects, the role of aviation regulator Directorate General of Civil Aviation (DGCA) will come under question.

“In all probability it could be a pilot error but one has to rule out any other reasons before arriving at a conclusion. Only a thorough enquiry will determine if the crew made a mistake or there was a malfunction or a previous record of defect in the aircraft systems,” said Capt Shakti Lumba, former head of operations at IndiGo, and an aviation safety expert.

Taking about the role of aviation regulator and its efficacy, he said the overall oversight mechanism was poor in the country. “Generally speaking, the regulatory oversight is poor because DGCA lacks manpower to conduct oversight over such a tremendously growing industry,” Lumba said.

“If you look at all previous international audits, whether it is FAA or ICAO, one thing there is that DGCA has been unable to exercise oversight over safety operations of all the airlines,” he noted.

Days back, an Air India flight saw failure of its Instrument Landing System (ILS) while landing at New York airport. IndiGo aircraft fitted with Pratt and Whitney engines too have frequently developed snags with the regulator grounding them. At least 30 passengers on a Jet Airways flight from Mumbai to Jaipur suffered nose and ear bleeding on Thursday after the crew “forgot” to turn on a switch that controls cabin air pressure, officials said.

The cockpit crew of the flight, which had 171 people on board, have been derostered and the Aircraft Accident Investigation Bureau (AAIB) has been directed to probe the incident. “During climb, the crew forgot to select bleed switch due to which cabin pressurisation could not be maintained. As a result, oxygen masks got deployed,” a DGCA official said.

In an official statement, a Jet Airways spokesperson said that the Boeing 737 aircraft returned to Mumbai due to “loss of cabin pressure” and the pilots have been taken off duty pending investigation.

As several incidents related to air safety have been reported recently, civil aviation minister Suresh Prabhu has ordered a safety audit of all scheduled airlines and airports.