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An ATR42 on descent into msp, mn, descends below cleared altitude of 11000 ft. Flight crew blames new cockpit procedures.
| Attributes | |
| ACN | 375330 |
| Time | |
| Date | 199707 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : grb |
| State Reference | WI |
| Altitude | msl bound lower : 10700 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zmp |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Transport, High Wing, 2 Turboprop Eng |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 7000 flight time type : 4000 |
| ASRS Report | 375330 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 12000 flight time type : 2500 |
| ASRS Report | 375421 |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were cleared pilot's discretion from 12000 ft to 11000 ft. When we called out of 12000 ft, I had thought the captain had set 11000 ft in autoplt when the original clearance was given. The new altitude was never set in. Because the new altitude was not set, the aircraft did not capture 11000 ft. I noticed this at about 10800 ft. By the time I turned off the autoplt and stopped the downward trend, we had descended to 10700 ft then immediately back to 11000 ft. As I was correcting the situation, ZMP asked our altitude. By the time I could answer we were back at 11000 ft. Human factors: this happened at the end of a 12 hour work day in very hot conditions. We were both very tired. I believe that is the reason we both missed this mistake. Also contributing could have been a change in our company procedures regarding altitude changes. Previously the PF will set the new altitude in the autoplt before beginning a change in altitude. The new procedure has the PNF set in the new altitude. Since the change I have noticed a large mix in methods used by pilots.
Original NASA ASRS Text
Title: AN ATR42 ON DSCNT INTO MSP, MN, DSNDS BELOW CLRED ALT OF 11000 FT. FLC BLAMES NEW COCKPIT PROCS.
Narrative: WE WERE CLRED PLT'S DISCRETION FROM 12000 FT TO 11000 FT. WHEN WE CALLED OUT OF 12000 FT, I HAD THOUGHT THE CAPT HAD SET 11000 FT IN AUTOPLT WHEN THE ORIGINAL CLRNC WAS GIVEN. THE NEW ALT WAS NEVER SET IN. BECAUSE THE NEW ALT WAS NOT SET, THE ACFT DID NOT CAPTURE 11000 FT. I NOTICED THIS AT ABOUT 10800 FT. BY THE TIME I TURNED OFF THE AUTOPLT AND STOPPED THE DOWNWARD TREND, WE HAD DSNDED TO 10700 FT THEN IMMEDIATELY BACK TO 11000 FT. AS I WAS CORRECTING THE SIT, ZMP ASKED OUR ALT. BY THE TIME I COULD ANSWER WE WERE BACK AT 11000 FT. HUMAN FACTORS: THIS HAPPENED AT THE END OF A 12 HR WORK DAY IN VERY HOT CONDITIONS. WE WERE BOTH VERY TIRED. I BELIEVE THAT IS THE REASON WE BOTH MISSED THIS MISTAKE. ALSO CONTRIBUTING COULD HAVE BEEN A CHANGE IN OUR COMPANY PROCS REGARDING ALT CHANGES. PREVIOUSLY THE PF WILL SET THE NEW ALT IN THE AUTOPLT BEFORE BEGINNING A CHANGE IN ALT. THE NEW PROC HAS THE PNF SET IN THE NEW ALT. SINCE THE CHANGE I HAVE NOTICED A LARGE MIX IN METHODS USED BY PLTS.
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.