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Crew failed to xchk altimeter settings which resulted in descending below cleared altitude.
| Attributes | |
| ACN | 428320 |
| Time | |
| Date | 199902 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : dvv.vortac |
| State Reference | CO |
| Altitude | msl bound lower : 16000 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | Mixed |
| Weather Elements | Turbulence |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other vortac |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival star : ramms 1 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : flight engineer pilot : cfi pilot : commercial |
| Experience | flight time last 90 days : 260 flight time total : 3000 flight time type : 1400 |
| ASRS Report | 428320 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : undershoot non adherence : clearance non adherence : published procedure |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued alert flight crew : returned to original clearance |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
How problem arose: captain set wrong altimeter setting, he set 30.34 instead of 29.34, causing us to cross a fix approximately 1000 ft low. Contributing factors: captain failed to announce transition level at FL180. I was occupied with informing our flight attendants of the turbulence and filling out the logbook, which took much longer than normal because of turbulence we were experiencing on our descent. If I had finished the logbook or set it aside to finish on the ground, I would have been in a better position to catch the error when it was made. How it was discovered: at the end of descent, ATC asked our altitude. I knew we were supposed to be at 17000 ft. I saw my altimeter was still at 29.92 and read 17200 or 17400 ft MSL. Realizing I had missed the transition altitude, I looked down to get the altimeter setting and crosschecked my captain, thinking he had missed it as well, only to see the wrong setting on his altimeter -- 30.34 instead of 29.34, putting us very low at our crossing. Corrective; we immediately climbed up to 17000 ft with the correct altimeter setting. By more closely following our SOP's we could have avoided this error. I can think of no procedure improvements. Only following what I already know to be good procedure would have stopped this.
Original NASA ASRS Text
Title: CREW FAILED TO XCHK ALTIMETER SETTINGS WHICH RESULTED IN DSNDING BELOW CLRED ALT.
Narrative: HOW PROB AROSE: CAPT SET WRONG ALTIMETER SETTING, HE SET 30.34 INSTEAD OF 29.34, CAUSING US TO CROSS A FIX APPROX 1000 FT LOW. CONTRIBUTING FACTORS: CAPT FAILED TO ANNOUNCE TRANSITION LEVEL AT FL180. I WAS OCCUPIED WITH INFORMING OUR FLT ATTENDANTS OF THE TURB AND FILLING OUT THE LOGBOOK, WHICH TOOK MUCH LONGER THAN NORMAL BECAUSE OF TURB WE WERE EXPERIENCING ON OUR DSCNT. IF I HAD FINISHED THE LOGBOOK OR SET IT ASIDE TO FINISH ON THE GND, I WOULD HAVE BEEN IN A BETTER POS TO CATCH THE ERROR WHEN IT WAS MADE. HOW IT WAS DISCOVERED: AT THE END OF DSCNT, ATC ASKED OUR ALT. I KNEW WE WERE SUPPOSED TO BE AT 17000 FT. I SAW MY ALTIMETER WAS STILL AT 29.92 AND READ 17200 OR 17400 FT MSL. REALIZING I HAD MISSED THE TRANSITION ALT, I LOOKED DOWN TO GET THE ALTIMETER SETTING AND XCHKED MY CAPT, THINKING HE HAD MISSED IT AS WELL, ONLY TO SEE THE WRONG SETTING ON HIS ALTIMETER -- 30.34 INSTEAD OF 29.34, PUTTING US VERY LOW AT OUR XING. CORRECTIVE; WE IMMEDIATELY CLBED UP TO 17000 FT WITH THE CORRECT ALTIMETER SETTING. BY MORE CLOSELY FOLLOWING OUR SOP'S WE COULD HAVE AVOIDED THIS ERROR. I CAN THINK OF NO PROC IMPROVEMENTS. ONLY FOLLOWING WHAT I ALREADY KNOW TO BE GOOD PROC WOULD HAVE STOPPED THIS.
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.