Narrative:

While on a 295 degree heading from dfw approach control, approximately 5 mi from the airport at 11000' assigned, we encountered an abrupt updraft associated with a thunderstorm (approximately 15-20 mi away) that sent the aircraft up 500', knocking the autoplt off. We climbed almost to 12000' before a correction was initiated. There was a very slight delay in recovery as the copilot momentarily looked at the above field level (afl) altimeter. A smooth recovery to 11000' was made. I do not think the deviation could have been avoided, but the recovery could have begun sooner. The confusion caused the copilot to look at the wrong altimeter--air carrier uses QFE and qnh. The copilot flies jets in the military reserves, and when flustered, reverted to his military training by looking at the altimeter on his instrument panel. I have flown with the QFE, qnh system for 11 yrs and amused to it, but I think it has outlived its usefulness now that there are radar altimeters to give AGL information.

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Original NASA ASRS Text

Title: UPDRAFT CAUSES WDB TO CLIMB ABOVE ASSIGNED ALT.

Narrative: WHILE ON A 295 DEG HDG FROM DFW APCH CTL, APPROX 5 MI FROM THE ARPT AT 11000' ASSIGNED, WE ENCOUNTERED AN ABRUPT UPDRAFT ASSOCIATED WITH A TSTM (APPROX 15-20 MI AWAY) THAT SENT THE ACFT UP 500', KNOCKING THE AUTOPLT OFF. WE CLBED ALMOST TO 12000' BEFORE A CORRECTION WAS INITIATED. THERE WAS A VERY SLIGHT DELAY IN RECOVERY AS THE COPLT MOMENTARILY LOOKED AT THE ABOVE FIELD LEVEL (AFL) ALTIMETER. A SMOOTH RECOVERY TO 11000' WAS MADE. I DO NOT THINK THE DEVIATION COULD HAVE BEEN AVOIDED, BUT THE RECOVERY COULD HAVE BEGUN SOONER. THE CONFUSION CAUSED THE COPLT TO LOOK AT THE WRONG ALTIMETER--ACR USES QFE AND QNH. THE COPLT FLIES JETS IN THE MIL RESERVES, AND WHEN FLUSTERED, REVERTED TO HIS MIL TRNING BY LOOKING AT THE ALTIMETER ON HIS INSTRUMENT PANEL. I HAVE FLOWN WITH THE QFE, QNH SYS FOR 11 YRS AND AMUSED TO IT, BUT I THINK IT HAS OUTLIVED ITS USEFULNESS NOW THAT THERE ARE RADAR ALTIMETERS TO GIVE AGL INFO.

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.