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BA3100 radar altimeter began to malfunction en route. Checked with maintenance to see if they should continue to mcw. Advised to call on the ground. Landed with ceiling 400 ft and visibility 1 mi. MEL requires 500 ft 1 mi with radar altimeter inoperative.
| Attributes | |
| ACN | 354189 |
| Time | |
| Date | 199611 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : mcw |
| State Reference | IA |
| Altitude | msl bound lower : 8000 msl bound upper : 8000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zmp |
| Operator | common carrier : air carrier |
| Make Model Name | Jetstream 31 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | cruise other descent : approach descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 2800 flight time type : 180 |
| ASRS Report | 354189 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : published procedure non adherence : far |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : detected after the fact |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
En route the radar altimeter started to swing rapidly (in cruise at 8000 ft), this generated GPWS warning. I suspected moisture in the system. We called maintenance on the radio and asked if they wanted us to continue. I knew this would affect further operation as low ceiling and visibility were widespread. Maintenance advised us to continue and call when we got on the ground in mcw. We did so. Only at that time did I note the MEL called for WX no lower than 500 ft 1 mi with the radar altimeter OTS. It was 300-400 ft and 1 mi in mcw when we landed. The only way to know this fact was to consult the MEL. At the time (night, IMC, ice, PF, no autoplt) it did not seem like a very practical thing to do. Unfortunately maintenance did not look at their MEL, and did not tell us about the restr. During training, calling maintenance for help was emphasized, looking in the MEL was not even discussed.
Original NASA ASRS Text
Title: BA3100 RADAR ALTIMETER BEGAN TO MALFUNCTION ENRTE. CHKED WITH MAINT TO SEE IF THEY SHOULD CONTINUE TO MCW. ADVISED TO CALL ON THE GND. LANDED WITH CEILING 400 FT AND VISIBILITY 1 MI. MEL REQUIRES 500 FT 1 MI WITH RADAR ALTIMETER INOP.
Narrative: ENRTE THE RADAR ALTIMETER STARTED TO SWING RAPIDLY (IN CRUISE AT 8000 FT), THIS GENERATED GPWS WARNING. I SUSPECTED MOISTURE IN THE SYS. WE CALLED MAINT ON THE RADIO AND ASKED IF THEY WANTED US TO CONTINUE. I KNEW THIS WOULD AFFECT FURTHER OP AS LOW CEILING AND VISIBILITY WERE WIDESPREAD. MAINT ADVISED US TO CONTINUE AND CALL WHEN WE GOT ON THE GND IN MCW. WE DID SO. ONLY AT THAT TIME DID I NOTE THE MEL CALLED FOR WX NO LOWER THAN 500 FT 1 MI WITH THE RADAR ALTIMETER OTS. IT WAS 300-400 FT AND 1 MI IN MCW WHEN WE LANDED. THE ONLY WAY TO KNOW THIS FACT WAS TO CONSULT THE MEL. AT THE TIME (NIGHT, IMC, ICE, PF, NO AUTOPLT) IT DID NOT SEEM LIKE A VERY PRACTICAL THING TO DO. UNFORTUNATELY MAINT DID NOT LOOK AT THEIR MEL, AND DID NOT TELL US ABOUT THE RESTR. DURING TRAINING, CALLING MAINT FOR HELP WAS EMPHASIZED, LOOKING IN THE MEL WAS NOT EVEN DISCUSSED.
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.