Narrative:

On WOBUN2F departure from lhr, we were leveling at 6000 ft when cleared by ATC to climb to FL70. Although previously briefed, none of us caught the transition level at 6000 ft. Due to the very low altimeter setting, the difference between 6000 ft and FL70 was only 400 ft. Climbing to FL70 with the altimeters set at 993 millibars caused us to overshoot our altitude by approximately 600 ft. ATC issued a descent clearance to FL70 and advised us to check, our altimeters for 1013 millibars. There were no TA's or RA's during the excursion. We were informed that there would be action taken. Supplemental information from acn 500039: correction to the above: the destination was boston. A contributing factor to this mistake was the low altitude workload inherent with terminal operations. Supplemental information from acn 500040: the field altimeter was 988 qne (29.17 qnh). During a busy part of the departure, accelerating to 290 (cleared unrestr departure), turning on the SID, changing radio frequency, and anticipating a large altimeter difference change (29.17 to 29.92), we incorrectly set the altimeters to 29.92 at 6000 ft when they should have stayed on 988 qne. This resulted in a large altitude deviation. A thorough understanding of the correct international altimeter procedures would have prevented this from happening. Know the different procedures for international flying.

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Original NASA ASRS Text

Title: B767-300 CREW HAD ALT OVERSHOOT IN EGLL CLASS B AIRSPACE DUE TO ALTIMETER SETTING ERRORS.

Narrative: ON WOBUN2F DEP FROM LHR, WE WERE LEVELING AT 6000 FT WHEN CLRED BY ATC TO CLB TO FL70. ALTHOUGH PREVIOUSLY BRIEFED, NONE OF US CAUGHT THE TRANSITION LEVEL AT 6000 FT. DUE TO THE VERY LOW ALTIMETER SETTING, THE DIFFERENCE BTWN 6000 FT AND FL70 WAS ONLY 400 FT. CLBING TO FL70 WITH THE ALTIMETERS SET AT 993 MILLIBARS CAUSED US TO OVERSHOOT OUR ALT BY APPROX 600 FT. ATC ISSUED A DSCNT CLRNC TO FL70 AND ADVISED US TO CHK, OUR ALTIMETERS FOR 1013 MILLIBARS. THERE WERE NO TA'S OR RA'S DURING THE EXCURSION. WE WERE INFORMED THAT THERE WOULD BE ACTION TAKEN. SUPPLEMENTAL INFO FROM ACN 500039: CORRECTION TO THE ABOVE: THE DEST WAS BOSTON. A CONTRIBUTING FACTOR TO THIS MISTAKE WAS THE LOW ALT WORKLOAD INHERENT WITH TERMINAL OPS. SUPPLEMENTAL INFO FROM ACN 500040: THE FIELD ALTIMETER WAS 988 QNE (29.17 QNH). DURING A BUSY PART OF THE DEP, ACCELERATING TO 290 (CLRED UNRESTR DEP), TURNING ON THE SID, CHANGING RADIO FREQ, AND ANTICIPATING A LARGE ALTIMETER DIFFERENCE CHANGE (29.17 TO 29.92), WE INCORRECTLY SET THE ALTIMETERS TO 29.92 AT 6000 FT WHEN THEY SHOULD HAVE STAYED ON 988 QNE. THIS RESULTED IN A LARGE ALTDEV. A THOROUGH UNDERSTANDING OF THE CORRECT INTL ALTIMETER PROCS WOULD HAVE PREVENTED THIS FROM HAPPENING. KNOW THE DIFFERENT PROCS FOR INTL FLYING.

Data retrieved from NASA's ASRS site as of July 2007 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.