Widebody; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Confusion; Situational Awareness
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Airspace Structure; Human Factors
I was the pilot flying and the Captain was the Pilot Monitoring. The relief officer was also in the flight deck. We were cleared Runway 27L WOBUN 3G SID. Transition Altitude was checked prior to departure. Once on the LAA Europe Reference; second on the WOBUN 3G departure page and third on our FMC. Transition altitude was 6;000 feet. After takeoff we were cleared to 6;000 feet. There was some confusion as to whether we should stay on 'QNH' or set 'QNE'. This was all remedied by the time we reached transition altitude of 6;000 feet. We were then cleared to FL080. This was a very quick climb and ATC queried us to check altitude and altimeters. We immediately set 'QNE' and descended to FL080. ATC alerted us of traffic and we confirmed traffic in sight visually. No loss of separation occurred.I think especially important in this instance that 6;000 feet is briefed as the transition altitude and our clearance limit on this particular SID. However; 'QNH' must be maintained at 6;000 feet if we level.  This is totally opposite of USA as Transition Altitude is FL180 and 'QNE' is set at transition altitude. I plan to incorporate after Captains pre-takeoff briefing i.e. before gate departure that if leveling at transition altitude we need to keep current 'QNH' set and not switch over to STD 'QNE'. Also; awareness of resetting all altimeters to STD 'QNE' as soon as vacating the transition altitude for higher Flight Level.
Departing LHR on the WOBUN 3G departure off runway 27L we climbed to 6;000 feet. When switched from the Tower to Departure the Captain (Pilot Monitoring) gave our call sign and said we were climbing from 40 to 60 (a common habit I find myself doing in the states; i.e. leaving ORD I would normally tell the departure controller '2 point 8 climbing 5 or some variation Thereof). But of course in the UK they speak of levels under 100 feet in two digit format. So I can see the controllers concern as to our intentions to level at FL 060 vs. 6;000 feet. The controller replied that we were cleared to 6;000 feet. At the same time we were approaching the 'Transition Altitude' (6;000 feet). As per our checklist and state side habit pattern I noticed the Captain reach down and switch to 'STD' altimeter setting. Both the First Officer (Pilot Flying) and I (relief officer) questioned this. As this was the sixth day of our six day trip we were all familiar with each other and the Captain quickly put our input to use and immediately questioned ATC. The controller clarified that indeed we were cleared to '6;000 feet' on a QNH. The captain changed his altimeter back to the QNH setting and the First Officer climbed an additional few hundred feet to be level. We remained at 6;000 feet for some time. Very unusual for LHR to leave us at that altitude for any amount of time in my experience. And I found that contributed to the issue. It felt out of our normal habit pattern.The next series of events happened very quickly. We received clearance to 'climb level Eight Zero'. The captain responded to the clearance and the First Officer input the new altitude in the FMC. I was thinking to myself as the clearance came over the radio and the crew responded that it was 'ok now to change to 'STD' altimeter'. I found myself wanting to say that; but was distracted watching the crew go through the process of verifying the change to FMC and then executing. At moderate weights and low altitudes there is enough reserve thrust for the aircraft to climb aggressively and that's exactly what the aircraft did. For a simple 2;000 foot change the aircraft started up at over 2;000 feet per minute. At the same time as the crew executed the climb command the TCAS gave us a 'TA' and the controller also chimed in with the traffic information. I saw the traffic and called it 'in sight 12 o'clock ' meanwhile the First Officer was busy leveling off and the Captain was busy answering the controllers second call that we were cleared 'level 080 QNH 1013' (i.e. 'STD')As the Captain and First Officer both changed their altimeters and the aircraft was leveling on autopilot the momentum of the climb was going to over shoot our altitude. First Officers disconnected the autopilot and leveled the aircraft at FL080. The traffic was passed us at this point and no conflict occurred but we all realized at the same time that during those few; fast and furious moments that a late change to the altimeters coupled with the performance of the aircraft had contributed greatly to the event. I had the missing piece to the puzzle and didn't speak up before I was distracted by 'waiting for the right opportunity to speak up' and looking for traffic announced by TCAS. It's a bit of an art to providing useful input as an relief officer and not add to the chaos. I believe I should have spoken sooner and in the future will do so weather its needed or not; so as to not miss the opportunity to add a positive piece of information to the crews situational awareness. Perhaps a vertical speed climb for 6;000 feet to FL080 would have produced more time for us to deal with the multiple inputs present in this scenario. The industry seems very focused on automation and 'V/S' climbs seem almost taboo. While it is always the pilots that are responsible to operate the aircraft in the appropriate mode. I think years of focus on automation may lead us down a path of over reliance. I certainlywill remember this lesson and if presented with a similar situation in the future; would elect a vertical speed climb versus VNAV.
An air crew on a departure were cleared to 6;000 feet. The Captain was confused about the transition level procedure and set the standard altimeter setting initially until he was corrected. ATC then cleared them to Flight Level 080; which they overshot because of not having the correct standard altimeter setting.