 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
B737-800 captain reported that an FMS malfunction resulted in an uncommanded climb during approach.
| Attributes | |
| ACN | 1700717 |
| Time | |
| Date | 201911 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.TRACON |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance |
Narrative:
Descending into ZZZ the aircraft locked onto a glideslope signal at around FL340 and started to climb. Took a couple of seconds to figure out what it was doing; but once I saw the G/south on the FMA was green (meaning it was locked on) it was clear the aircraft thought it should follow the glide slope so it started a climb. At that point the autopilot was disconnected and ATC was notified that we had a problem. All the automation was turned off and once the aircraft was stable in the descent the automation LNAV/VNAV etc.; was re-established. Aircraft landed safely in ZZZ and was turned over to maintenance. They discovered that the FCC computer on the a side had tripped a fault code and placarded the autopilot a inoperative. Flew the aircraft back to ZZZ on autopilot B with no issues.
Original NASA ASRS Text
Title: B737-800 Captain reported that an FMS malfunction resulted in an uncommanded climb during approach.
Narrative: Descending into ZZZ the aircraft locked onto a glideslope signal at around FL340 and started to climb. Took a couple of seconds to figure out what it was doing; but once I saw the G/S on the FMA was green (meaning it was locked on) it was clear the aircraft thought it should follow the glide slope so it started a climb. At that point the autopilot was disconnected and ATC was notified that we had a problem. All the automation was turned off and once the aircraft was stable in the descent the automation LNAV/VNAV etc.; was re-established. Aircraft landed safely in ZZZ and was turned over to Maintenance. They discovered that the FCC computer on the A side had tripped a fault code and placarded the autopilot A inoperative. Flew the Aircraft back to ZZZ on autopilot B with no issues.
Data retrieved from NASA's ASRS site 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.