(CNN)A Jet Airways flight from Mumbai to Jaipur was forced to turn back Thursday after around 30 passengers complained of nose and ear bleeds due to low pressure in the cabin.
"The B737 aircraft, with 166 guests and 5 crew landed normally in Mumbai," Jet Airways said in a statement. "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."
An official with the Directorate General of Civil Aviation (DGCA) told CNN affiliate CNN News 18 that the crew allegedly forgot to press a button to pressurize the cabin.
"During climb, crew forgot to select bleed switch due to which cabin pressurization could not be maintained, and oxygen masks got deployed," the official said.
In the statement, Jet Airways said Flight 9W697 "made an air turn back due to loss in cabin pressure." A spokeswoman refused to confirm the claim that the crew forgot to press the button.
Videos from the flight posted online showed passengers wearing oxygen masks, which automatically deploy if there is a drop in pressure.
"I saw many people having nose bleeds," passenger Joel D'Souza told CNN. "I took off my oxygen mask for one second and felt so stuffy and hot in the cabin. There was no announcement by the crew and nobody knew what to do."
He said he and other passengers had since boarded another flight that was about to depart around 11.00 a.m. local time.
Jet Airways said the flight's cockpit crew "has been taken off scheduled duties pending investigation," and it was making alternative arrangements for passengers on board.
Aircraft fly at an altitude where the air pressure is far lower than our bodies are used to, which also means there is less oxygen available for us to breathe.
Because of this, aircraft are pressurized to simulate a lower altitude inside the cabin. As an aircraft climbs to a high altitude, the cabin is pressurized, and as it descends for landing, it is gradually de-pressurized.
Low pressure air is thinner and drier, which can cause nosebleeds.