|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||atc facility : bdf|
|Altitude||msl bound lower : 23500|
msl bound upper : 24000
|Controlling Facilities||artcc : zau|
|Operator||common carrier : air carrier|
|Make Model Name||Medium Large Transport, Low Wing, 2 Turbojet Eng|
|Flight Phase||descent other|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : instrument|
pilot : commercial
pilot : atp
pilot : flight engineer
|Experience||flight time last 90 days : 100|
flight time total : 6200
|Function||flight crew : first officer|
|Qualification||pilot : commercial|
pilot : instrument
|Anomaly||aircraft equipment problem : less severe|
altitude deviation : overshoot
|Independent Detector||aircraft equipment other aircraft equipment : unspecified|
other flight crewa
|Resolutory Action||flight crew : returned to intended course or assigned course|
|Air Traffic Incident||other|
The aircraft altitude alert system was inoperative so we were extra aware of altitude. During descent, on autoplt, I was leveling off at FL240, making a small correction on vertical speed, when the autoplt started a rapid descent. The descent went to 23550', approximately, and I recovered it back to FL240. Center didn't say anything to us about it. I don't know how to do anything different if it occurred again.
Original NASA ASRS Text
Title: AUTOPLT BEGAN A RAPID DESCENT WHEN THE FLT CREW ATTEMPTED TO LEVEL OFF AT ASSIGNED ALT.
Narrative: THE ACFT ALT ALERT SYSTEM WAS INOP SO WE WERE EXTRA AWARE OF ALT. DURING DESCENT, ON AUTOPLT, I WAS LEVELING OFF AT FL240, MAKING A SMALL CORRECTION ON VERTICAL SPEED, WHEN THE AUTOPLT STARTED A RAPID DESCENT. THE DESCENT WENT TO 23550', APPROX, AND I RECOVERED IT BACK TO FL240. CENTER DIDN'T SAY ANYTHING TO US ABOUT IT. I DON'T KNOW HOW TO DO ANYTHING DIFFERENT IF IT OCCURRED AGAIN.
Data retrieved from NASA's ASRS site as of August 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.