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Captain inadvertently moved the altitude alerter while silencing the gear horn in a DC9-30. He reset it to the wrong altitude and failed to level off at the assigned altitude.
| Attributes | |
| ACN | 396310 |
| Time | |
| Date | 199803 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : gep airport : msp |
| State Reference | MN |
| Altitude | msl bound lower : 10500 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zmp tracon : sju |
| Operator | common carrier : air carrier |
| Make Model Name | DC-9 30 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | arrival other enroute airway : zmp |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 3400 flight time type : 180 |
| ASRS Report | 396310 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 150 flight time total : 11500 flight time type : 1300 |
| ASRS Report | 396410 |
| Events | |
| Anomaly | altitude deviation : crossing restriction not met altitude deviation : overshoot non adherence : clearance non adherence other other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Aircraft was assigned 11000 ft MSL for descent into minneapolis. The altitude alert altitude was set at 11000 ft and the captain initiated the descent. While silencing the gear warning alert as throttles were retarded to idle, the altitude knob for the altitude alert was moved indicating 10400 ft. The captain (PF) set the alert knob to 10000 ft. Passing 10500 ft the captain asked what altitude we were cleared to. I immediately called ZMP and advised that we were descending through 10500 ft and asked what was our assigned altitude, 10000 ft or 11000 ft? ZMP advised us to continue our descent to 10000 ft. This was a very busy time in the cockpit and as the first officer (PNF) I did not see the captain reset the altitude alert altitude. I was accomplishing my checklist during the unintentional descent below the assigned altitude of 11000 ft. I believe it is important to monitor the leveloff while accomplishing other cockpit duties. Fortunately, no other aircraft were in our vicinity at the time of this incident. Supplemental information from acn 396410: if I had confirmed the 10000 ft with the first officer, and/or ATC, we could have avoided this. The gear horn is also very close to the altitude alerter in some DC9's. On other aircraft the gear horn button is farther down the dash and away from the alerter.
Original NASA ASRS Text
Title: CAPT INADVERTENTLY MOVED THE ALT ALERTER WHILE SILENCING THE GEAR HORN IN A DC9-30. HE RESET IT TO THE WRONG ALT AND FAILED TO LEVEL OFF AT THE ASSIGNED ALT.
Narrative: ACFT WAS ASSIGNED 11000 FT MSL FOR DSCNT INTO MINNEAPOLIS. THE ALT ALERT ALT WAS SET AT 11000 FT AND THE CAPT INITIATED THE DSCNT. WHILE SILENCING THE GEAR WARNING ALERT AS THROTTLES WERE RETARDED TO IDLE, THE ALT KNOB FOR THE ALT ALERT WAS MOVED INDICATING 10400 FT. THE CAPT (PF) SET THE ALERT KNOB TO 10000 FT. PASSING 10500 FT THE CAPT ASKED WHAT ALT WE WERE CLRED TO. I IMMEDIATELY CALLED ZMP AND ADVISED THAT WE WERE DSNDING THROUGH 10500 FT AND ASKED WHAT WAS OUR ASSIGNED ALT, 10000 FT OR 11000 FT? ZMP ADVISED US TO CONTINUE OUR DSCNT TO 10000 FT. THIS WAS A VERY BUSY TIME IN THE COCKPIT AND AS THE FO (PNF) I DID NOT SEE THE CAPT RESET THE ALT ALERT ALT. I WAS ACCOMPLISHING MY CHKLIST DURING THE UNINTENTIONAL DSCNT BELOW THE ASSIGNED ALT OF 11000 FT. I BELIEVE IT IS IMPORTANT TO MONITOR THE LEVELOFF WHILE ACCOMPLISHING OTHER COCKPIT DUTIES. FORTUNATELY, NO OTHER ACFT WERE IN OUR VICINITY AT THE TIME OF THIS INCIDENT. SUPPLEMENTAL INFO FROM ACN 396410: IF I HAD CONFIRMED THE 10000 FT WITH THE FO, AND/OR ATC, WE COULD HAVE AVOIDED THIS. THE GEAR HORN IS ALSO VERY CLOSE TO THE ALT ALERTER IN SOME DC9'S. ON OTHER ACFT THE GEAR HORN BUTTON IS FARTHER DOWN THE DASH AND AWAY FROM THE ALERTER.
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.