AirAsia has been asked to re-evaluate its safety briefing after an incident on a flight between Perth and Denpasar in October 2017. During the incident in which oxygen masks were deployed, not all masks did so and not all masks worked, causing a degree of confusion in the cabin and for passengers to ignore seatbelt lights as they searched for working oxygen masks.
Problems in the cabin during an emergency descent
As reported in Australian Aviation, an AirAsia A320 was flying from Perth to Denpasar on October 15, 2017. Shortly after takeoff, there was a high cabin altitude master warning. The Australian Transport and Safety Bureau (ATSB) who investigated the incident determined there was an “intermittent rare fault” with the cabin pressure controller 1 circuit board. This caused an incorrect control of the outflow valve, leading to over-pressurization of the aircraft cabin and activation of the cabin safety valves and alerts of excess cabin altitude.
Following the alerts, the pilots asked ATC for an emergency descent from 34,000 feet to 10,000 feet, informed the passengers and deployed oxygen masks.
According to the ATSB report, not all masks deployed and some of those that did deploy did not work properly. Some of the passengers ignored crew instructions, getting out of their seats and looking for oxygen masks that did work.
At the time the seatbelt light was on and the crew were shouting instructions such as “brace”,“sit down”, “get down,” and “grab mask, fasten seatbelt, breathe normally”. According to the ATSB, these could have had the effect of furthering fear and confusion amongst the passengers.
The aircraft landed in Perth safely. The crew appear not to have handled the disembarkation process particularly well. The ATSB report says;
“During disembarkation she then received several passenger reports of the cabin crew members at the rear panicking, shouting and alarming the children.”
It was also noted that some passengers had put on life jackets.
Passenger confusion around oxygen masks
The ATSB investigation revealed over half of the passengers were “unsure” if their masks were working correctly. Many passengers were also unclear about how to operate the oxygen masks. The ATSB investigation found when the release pin was removed, the oxygen canister did not work in six seats. In another six seats, the oxygen masks did not deploy. In a further three seats, no lanyards were pulled to commence the flow of oxygen.
The ATSB investigation found that both the pre-flight safety briefing and the safety card did not clearly demonstrate how to activate the flow of oxygen. The ATSB report said;
“The ATSB recommends that AirAsia Indonesia take further action to review its current passenger pre-flight safety briefing and safety information card to ensure passengers are provided with clear instructions on how to activate the flow of oxygen from the passenger oxygen masks and that the bag may not inflate when oxygen is flowing.”
The ATSB findings and AirAsia’s response
The ATSB found the contributing factors to the incident was a minor intermittent fault with the active cabin pressure controller. Airbus has reviewed its A320 emergency procedures when an incident like this occurs. Airbus now recommends and has implemented a manual cabin pressure controller changeover in case of abnormal cabin altitude.
The ATSB found the lack of clear instructions in both the pre-flight safety briefing and in the safety cards, combined with inappropriate commands from the cabin crew for a rapid descent and depressurization, along with a failure to deal with non-compliant passenger behavior were factors that increased risk.
AirAsia flies to several Australian cities, including Melbourne, Perth, Brisbane, Adelaide and Sydney. The airline told the ATSB that it was adhering to Indonesian regulations and that it would “consider” including the requirements in its safety demonstration announcements.