B777-200
Flight Crew Air Transport Pilot (ATP)
Workload; Training / Qualification; Fatigue; Human-Machine Interface; Time Pressure; Communication Breakdown; Confusion; Distraction
Aircraft Equipment Problem Critical; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Clearance
Airspace Structure; Weather; Procedure; Human Factors
At the end of a long flight to Guangzhou; while on the arrival and cleared down to 2;400 meters; we went about 300 FT low as the crew set altimeters as leveling vice as coming through the transition level of 3;300 meters. The QNH at the time 1000 HP. Several factors can be factored into the event; 1. Long day (fatigue) 2. Weather associated with a typhoon 3. Operating in the China meters environment 4. Communication challenges with the Chinese Controller 5. Change of arrivals [at] the transition level switch of the altimeters was missed by the entire crew as we descended; and to the best I can recall it was about this time that the Controller finally assigned an arrival which was different from what we had loaded/expected. We had the GYA 1W arrival loaded and were switched to the GYA 1Y arrival.I could have done a better job backing up the Captain and First Officer. We had several times in the descent where it was tough to understand the Controller's instructions and it was an extremely busy on the radios due to the amount of arrival traffic and weather in the area from the outer bands of the typhoon. We could have queried the Controller on what arrival to expect sooner to avoid the higher workload of switching the arrivals while descending. This is only the second trip I have flown as a Relief Pilot and wasn't really sure what I should be concentrating my attention on while backing up the front end crew. In the future I will be more diligent in watching the arrival procedures and try to maintain better overall situational awareness.
Typhoon-type weather conditions in area with lots of CBs and turbulence. While descending; vectored off arrival due traffic. While on vector arrival changed to GYA 1W for 02L. Crew accomplished change and noted new mins. Then re-vectored back to arrival and arrival changed back to original. Change again accomplished. Then Approach Control descended aircraft to 2;400 meters/7;900 FT (TL FL108; TA 8;860 FT). Approach did not issue altitude instruction with the normal: 'Descent to 2;400 meters on altimeter 1000 HP.' I was concentrating on a large storm at 12 o'clock and trying to get the aircraft down to 7;900 FT as quickly as possible as we were in the approach environment and high; when I saw the altimeter display go yellow at 8;800 FT. We switched altimeters from STD to 1000 HP passing 8;500 FT. Indicated altitude immediately changed to 8;100 FT and the aircraft failed to capture altitude at 7;900 FT. Both the FO and I realized the problem. I disconnected the autopilot passing about 7;850 feet and arrested sink rate. Altitude bottomed out between 7;600 and 7;500 FT and quickly was corrected back to 7;900 feet (2;400 meters).  The Approach Controller must have realized he had not given us the local altimeter setting when descending us below the TL because when he queried us about our altitude he told us to make certain we were on the local altimeter setting of 1000 HP. This pairing which arrives in Guangzhou at around XA30PM is a very fatiguing; back-side-of-the-clock schedule. It is augmented with only a single relief pilot even though it routinely pushes 12 block hours and ends with a demanding descent and approach. When coupled with a weather event such as the typhoon conditions encountered on this trip; it is quite challenging.
The single augmented flight crew of a B777-200; at the end of a 12 hour flight to ZGGG including avoiding typhoon weather; failed to reset their altimeters in a timely fashion as the passed the Transition Level and descended below their cleared altitude.  Fatigue and metric altimetry at low transition levels were cited as contributing factors.