Narrative:

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 standard 'qne'. Also; awareness of resetting all altimeters to standard 'qne' as soon as vacating the transition altitude for higher flight level.

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Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.