 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Flight crew of medium large transport descending adjusted the vertical speed rate which took the autoplt out of capture mode. Descended 350 ft below assigned altitude.
| Attributes | |
| ACN | 382700 |
| Time | |
| Date | 199710 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : cae |
| State Reference | SC |
| Altitude | msl bound lower : 10650 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zjx |
| Operator | common carrier : air carrier |
| Make Model Name | MD-88 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial |
| Experience | flight time last 90 days : 180 flight time total : 5800 flight time type : 3400 |
| ASRS Report | 382700 |
| 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 : 125 flight time total : 6200 flight time type : 424 |
| ASRS Report | 382545 |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance |
| 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:
We were descending to assigned altitude of 11000 ft. ZJX gave a frequency change for columbia approach passing 12000 ft. Aircraft was in an IAS idle descent. Just as the autoplt captured 11000 ft and switched to vertical speed for the leveloff, the captain adjusted the vertical speed rate which unknowingly took the autoplt out of capture mode. The aircraft continued to descend through the assigned altitude of 11000 ft. It reached 10650 ft before the descent could be stopped and the aircraft returned to 11000 ft. Contributing factors included the frequency change just prior to level off and the captain's possible unfamiliarity with the aircraft (4-6 months in type). The captain initially tried to arrest the descent through the autoplt controls versus disconnecting the autoplt and taking manual control which may have been more effective. As first officer and the PNF, I assisted with aircraft control only when it was apparent the captain was having trouble stopping the descent. No comments were made by the controllers during this event.
Original NASA ASRS Text
Title: FLC OF MLG DSNDING ADJUSTED THE VERT SPD RATE WHICH TOOK THE AUTOPLT OUT OF CAPTURE MODE. DSNDED 350 FT BELOW ASSIGNED ALT.
Narrative: WE WERE DSNDING TO ASSIGNED ALT OF 11000 FT. ZJX GAVE A FREQ CHANGE FOR COLUMBIA APCH PASSING 12000 FT. ACFT WAS IN AN IAS IDLE DSCNT. JUST AS THE AUTOPLT CAPTURED 11000 FT AND SWITCHED TO VERT SPD FOR THE LEVELOFF, THE CAPT ADJUSTED THE VERT SPD RATE WHICH UNKNOWINGLY TOOK THE AUTOPLT OUT OF CAPTURE MODE. THE ACFT CONTINUED TO DSND THROUGH THE ASSIGNED ALT OF 11000 FT. IT REACHED 10650 FT BEFORE THE DSCNT COULD BE STOPPED AND THE ACFT RETURNED TO 11000 FT. CONTRIBUTING FACTORS INCLUDED THE FREQ CHANGE JUST PRIOR TO LEVEL OFF AND THE CAPT'S POSSIBLE UNFAMILIARITY WITH THE ACFT (4-6 MONTHS IN TYPE). THE CAPT INITIALLY TRIED TO ARREST THE DSCNT THROUGH THE AUTOPLT CTLS VERSUS DISCONNECTING THE AUTOPLT AND TAKING MANUAL CTL WHICH MAY HAVE BEEN MORE EFFECTIVE. AS FO AND THE PNF, I ASSISTED WITH ACFT CTL ONLY WHEN IT WAS APPARENT THE CAPT WAS HAVING TROUBLE STOPPING THE DSCNT. NO COMMENTS WERE MADE BY THE CTLRS DURING THIS EVENT.
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.