What happened
On 30 August 2013, an Air New Zealand Boeing 737-300 was performing a scheduled flight from Wellington to Auckland. During the descent phase of the flight, the aircraft experienced a loss of cabin pressure. In response to the depressurisation, the flight crew initiated emergency protocols. The aircraft subsequently completed a safe landing at Auckland Airport. There were no injuries reported, and the aircraft sustained no damage during the event.
The investigation
The Transport Accident Investigation Commission (TAIC) conducted an extensive investigation into the incident, which included a specialized examination of the aircraft's pressurisation system and rigorous testing. Despite these efforts, investigators were unable to pinpoint a definitive cause for the loss of pressure. However, the investigation could not rule out the possibility that an intermittent fault within the air-conditioning or pressurisation systems was responsible.
Findings
The investigation highlighted several critical safety concerns regarding crew performance and training. Specifically, the inquiry found that the crew did not strictly follow the published emergency checklists designed for cabin depressurisation. Furthermore, there were identified deficiencies in how cabin crew were trained to utilize emergency oxygen equipment and execute depressurisation procedures.
Another significant finding involved the risk of the cabin remaining pressurized while on the ground. The investigation noted that if the Cabin Altitude Warning checklist is used, there is a potential for the cabin to remain pressurized, which could make opening aircraft doors extremely difficult and delay evacuations. Following this inquiry, Boeing updated its checklists to mitigate this specific risk.
Safety action
While the operator took steps to address the identified training and checklist adherence issues, the Commission did not issue formal recommendations regarding those specific findings. However, the inquiry emphasized the necessity of complete checklist adherence and the importance of thorough crew training on emergency equipment to ensure passenger and crew safety during high-workload events.