 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Air carrier MD82 flight crew first officer inadvertently disarms autoplt in descent while inputting speed data into the digital flight guidance panel. Descent through assigned altitude was observed by the flight crew when below 11000 ft. ATC notification was made and the aircraft returned to assigned altitude. PIC alleges that manipulating the digital flight guidance system in the MD82 is a big hurdle to overcome in the aircraft.
| Attributes | |
| ACN | 410758 |
| Time | |
| Date | 199808 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : sfo |
| State Reference | CA |
| Altitude | msl bound lower : 10500 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : oak |
| Operator | common carrier : air carrier |
| Make Model Name | MD-82 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : atp pilot : instrument |
| Experience | flight time last 90 days : 150 flight time total : 7000 flight time type : 150 |
| ASRS Report | 410758 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi pilot : flight engineer pilot : commercial |
| Experience | flight time last 90 days : 105 flight time total : 13010 flight time type : 9010 |
| ASRS Report | 410900 |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance other anomaly other |
| Independent Detector | 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:
Was told to maintain 11000 ft, but descended to 10500 ft. Autoplt did not capture altitude. Do not depend on autoplt to do the job. You must scan at all times. Supplemental information from acn 410900: copilot was flying with #2 autoplt engaged descending to 11000 ft with that altitude armed for capture by autoplt. In diagnosis of what caused the altitude incursion, copilot had made a digital flight guidance panel selection to reduce airspeed, however the flight guidance and autoplt had already captured the armed altitude of 11000 ft and was beginning to level off. The selection made by the copilot 'disarmed' the altitude capture and reversed the digital flight guidance to a vertical speed mode descent and aircraft continued to descend below 11000 ft. Had I seen it, I could have canceled his selection, re-armed the altitude and prevented incursion. Understanding and manipulating the digital flight guidance system is probably the biggest hurdle to overcome in this aircraft.
Original NASA ASRS Text
Title: ACR MD82 FLC FO INADVERTENTLY DISARMS AUTOPLT IN DSCNT WHILE INPUTTING SPD DATA INTO THE DIGITAL FLT GUIDANCE PANEL. DSCNT THROUGH ASSIGNED ALT WAS OBSERVED BY THE FLC WHEN BELOW 11000 FT. ATC NOTIFICATION WAS MADE AND THE ACFT RETURNED TO ASSIGNED ALT. PIC ALLEGES THAT MANIPULATING THE DIGITAL FLT GUIDANCE SYS IN THE MD82 IS A BIG HURDLE TO OVERCOME IN THE ACFT.
Narrative: WAS TOLD TO MAINTAIN 11000 FT, BUT DSNDED TO 10500 FT. AUTOPLT DID NOT CAPTURE ALT. DO NOT DEPEND ON AUTOPLT TO DO THE JOB. YOU MUST SCAN AT ALL TIMES. SUPPLEMENTAL INFO FROM ACN 410900: COPLT WAS FLYING WITH #2 AUTOPLT ENGAGED DSNDING TO 11000 FT WITH THAT ALT ARMED FOR CAPTURE BY AUTOPLT. IN DIAGNOSIS OF WHAT CAUSED THE ALT INCURSION, COPLT HAD MADE A DIGITAL FLT GUIDANCE PANEL SELECTION TO REDUCE AIRSPD, HOWEVER THE FLT GUIDANCE AND AUTOPLT HAD ALREADY CAPTURED THE ARMED ALT OF 11000 FT AND WAS BEGINNING TO LEVEL OFF. THE SELECTION MADE BY THE COPLT 'DISARMED' THE ALT CAPTURE AND REVERSED THE DIGITAL FLT GUIDANCE TO A VERT SPD MODE DSCNT AND ACFT CONTINUED TO DSND BELOW 11000 FT. HAD I SEEN IT, I COULD HAVE CANCELED HIS SELECTION, RE-ARMED THE ALT AND PREVENTED INCURSION. UNDERSTANDING AND MANIPULATING THE DIGITAL FLT GUIDANCE SYS IS PROBABLY THE BIGGEST HURDLE TO OVERCOME IN THIS ACFT.
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.