Description
On 1 June 2019, a Boeing 787-8 (JA828A) being operated by All Nippon Airways (ANA) on a scheduled international passenger flight from San Jose USA to Narita as ANA171 with an augmented flight crew of three pilots was in the cruise in day VMC when both air conditioning packs failed. A descent at normal rate was commenced and converted to an emergency descent when the cabin altitude reached 10,000 feet,at which point an emergency was declared. The flight thereafter was completed without further event.
Investigation
The event was classified as a Serious Incident and an Investigation was carried out by the Japan Transport Safety Board (JTSB). Relevant information was downloaded from the on- board EAFR (Enhanced Airborne Flight Recorders) and AMF-CPL (Airplane Condition Monitoring Function - Continuous Parameter Logging) and was also available from crew statements and ATC communications and radar recordings.
At the time of the event, the 50 year-old Captain, who had a total of 13,368 hours flying experience of which 2,004 hours were on type, was acting as PF and the 48 year-old relief pilot, who had a total of 10,545 hours flying experience of which 1,472 hours were on type, was occupying the First Officer’s seat.
What Happened
When level at FL 430 a little over 9 hours flight time since takeoff, thrust was reduced to slow down slightly from M 0.84 to M 0.78 in order to meet the required destination ETA. Soon after this, the EICAS indicated that the left side air conditioning pack had failed and on checking the operating status of the system on the MFDU it was found both left side Cabin Air Compressors had shut down.
