: More than 30 passengers, some bleeding from their noses and ears, have received treatment after pilots "forgot" to turn on a switch regulating cabin pressure, officials said.
Jet Airways flight 9W 697 from to Jaipur turned back shortly after take off.
Videos tweeted by passengers aboard the plane showed oxygen masks deployed inside the aircraft.
The aviation ministry said the cockpit crew had been taken off duty pending an investigation.
Jet Airways said in a statement that Thursday morning's flight had turned back "due to loss in cabin pressure" and "regretted" the inconvenience caused to its passengers.
"The B737 aircraft, with 166 guests and 5 crew landed normally in . All guests were deplaned safely and taken to the terminal. First aid was administered to few guests who complained of ear pain, bleeding nose etc," the statement said.
The airline said it was co-operating fully with the DGCA investigation.