More than 13 years ago, a Boeing aircraft crashed in a hilly terrain in Greece snuffing out 121 lives. A year later, investigators concluded that omissions in controlling cabin pressure was a key reason for the crash. On Thursday morning, the 166 passengers on board a Jet Airways flight might not have been aware about the incident that happened in Greece over a decade ago. But, they faced a similar situation as the cockpit crew forgot to control cabin pressure. At least 30 passengers on the airlines Mumbai-Jaipur flight suffered nasal and ear bleeding and headache as the Boeing 737-800 aircraft returned to Mumbai within minutes of take-off. Both the pilots – commander and copilot – have been de-rostered, an investigation has been ordered and the airline has expressed regret over the incident. According to two senior pilots and regulatory officials, Thursdays incident could be due to human negligence as checking cabin pressure is part of standard checks carried out before operation of a flight. Nasal and ear bleeding of air passengers due to de-pressurisation of cabin is a rare occurrence, the two senior pilots who are working with two different airlines told PTI. One of them operates Boeing planes and the other Airbus aircraft. One of the pilots said that generally, an aircraft is pressurised to 8,000 feet so that the pressure is adequate for the human body. Normally, a plane flies at an altitude of around 35,000 feet. A pilot said de-pressurisation could even result in hypoxia for the people on board. Hypoxia or lack of adequate oxygen supply for the human tissues, can cause various problems, including deterioration in a cognitive abilities. According to a doctor at Dr Balabhai Nanavati Hospital in Mumbai, five Jet Airways passengers who were on board the flight were suffering from mild conductive deafness. As per their preliminary examination by ENT doctors, the five passengers suffered barotrauma of ear, which is caused due to a change in air pressure, said Rajendra Patankar, chief operating officer at the hospital. There were 171 people on board, including 5 crew members. A passenger, who was in the flight, recalled a fellow passenger with bleeding nose.