Flight returns as oxygen masks fail to operate mid-air

Before every flight, airlines assure travellers that the overhead masks will deploy in case the cabin pressure dips. But on a recent Delhi-Addis Ababa flight, when the pressure dipped soon after take-off, all the masks did not get deployed, while some didn’t have air flow in them.

Luckily, the aircraft was not at a cruising altitude. It quickly descended to 10,000 feet — where breathing without pressurisation was possible — before returning to land safely in Delhi.

The scare happened on Ethiopian Airlines' flight ET-687 on September 15, which took off with 223 passengers for Addis Ababa at 6.40am. "When the Boeing 767 (ET-ALO) was at 34,000 feet at 7.08am, it reported cabin pressurisation failure to Delhi air traffic control and descended to 10,000 feet. Several passengers and crew masks did not deploy after passenger oxygen switch was activated. There was no oxygen flow in some of the masks," said a source.

In a statement, Ethiopian Airlines claimed: "While our flight ET-687 took-off for a scheduled service from Delhi to Addis Ababa, a remark with a small technical problem appeared in the cockpit and our crew decided to return to fix the problem. The aircraft landed safely at 7.53am and the flight continued after fixing the technical remark."

A team from Directorate General of Civil Aviation (DGCA) inspected the 15-yearold B767 on Monday under the safety assessment for foreign aircraft (SAFA) programme.

According to a source, the regulatory team found discrepancies, including aircraft registration not being on the identification plate, fuel being less by more than a tonne — though within aircraft operation limits, technical log book not filled properly by flight crew with details of flight and fuel and chocks on and chocks off (triangular blocks put in front of tyres to ensure a parked aircraft does not move) time not being noted. "These are significant findings and are being conveyed to the Ethiopian aviation regulator," said the source.

The aircraft was grounded in Delhi for a couple of days for replacement of the oxygen generator and low limit valve.

SAFA inspections are carried out all over the world with the local aviation safety authorities checking the aircraft of foreign airlines.

Indian-registered aircraft are also inspected at airports abroad. A few years ago, a leading Indian carrier had to instruct its pilots not to leave the aircraft before passengers at foreign airports.