More than 30 passengers from India experienced bleeding from the nose and ears after pilots on their plane "forgot" to turn on cabin pressure, according to multiple news reports.
Jet Airways flight 697 from Mumbai to Jaipur turned around after it took off after the pressure dropped inside the plane.
Oxygen bags deployed from above the seats.
"During climb, the crew forgot to select bleed switch due to which cabin pressure could not be maintained. As a result, oxygen masks got deployed," Lalit Gupta, joint director general working for the Directorate General of Civil Aviation, told Newsweek.
The airline said in a statement that the flight turned around "due to loss in cabin pressure" and "regretted" what happened.
"The B737 aircraft, with 166 guests and 5 crew, landed normally in Mumbai. All guests were deplaned safely and taken to the terminal. First aid was administered to a few guests who complained of ear pain, bleeding nose, etc," the statement said.
Passengers shared videos of what happened on the plane through social media.
Symptoms suffered by the passengers are common when a plane has low air pressure, according to Newsweek.
"To survive high altitudes, occupants of an aircraft need help breathing. The solution is to pump air into the airplane, so the interior pressure is high enough to keep the humans happy," according to AeroSavvy.
Jet Airways grounded two pilots back in January after reports of a fight inside the cockpit during a flight, according to BBC News. The flight landed safely.