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EMB145 aircraft warning system momentarily activated; disconnecting autoplt resulting in altitude overshoot.
| Attributes | |
| ACN | 747122 |
| Time | |
| Date | 200707 |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : pdx.tracon |
| State Reference | OR |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : pdx.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | EMB ERJ 145 ER&LR |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : approach |
| Route In Use | approach : visual |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 120 flight time total : 2800 flight time type : 1700 |
| ASRS Report | 747122 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance |
| Primary Problem | Aircraft |
Narrative:
We had been cleared to 4000 ft; and during the descent; we experienced unrelated electronic 'nuisance warnings' from the airplane. One of these kicked the autopilot off; with no annunciation of it. We descended 250 ft below the 4000 foot clearance; and were making corrections. Before returning completely to the assigned altitude; though; and only a few seconds later; we were cleared for the visual approach. There were no other aircraft in the area and there was no conflict. Visual conditions prevailed and we could see the airport clearly. These aircraft are getting older; and the volume of these 'nuisance warnings' has increased dramatically. These are warnings that go off; indicating a problem; but then disappear a few seconds later; leaving no indication that the warning ever existed. Additionally; more diligent scan of the instruments during the critical leveling off phase of the descent would have avoided this issue also.
Original NASA ASRS Text
Title: EMB145 ACFT WARNING SYSTEM MOMENTARILY ACTIVATED; DISCONNECTING AUTOPLT RESULTING IN ALT OVERSHOOT.
Narrative: WE HAD BEEN CLRED TO 4000 FT; AND DURING THE DSCNT; WE EXPERIENCED UNRELATED ELECTRONIC 'NUISANCE WARNINGS' FROM THE AIRPLANE. ONE OF THESE KICKED THE AUTOPILOT OFF; WITH NO ANNUNCIATION OF IT. WE DESCENDED 250 FT BELOW THE 4000 FOOT CLRNC; AND WERE MAKING CORRECTIONS. BEFORE RETURNING COMPLETELY TO THE ASSIGNED ALTITUDE; THOUGH; AND ONLY A FEW SECONDS LATER; WE WERE CLRED FOR THE VISUAL APCH. THERE WERE NO OTHER ACFT IN THE AREA AND THERE WAS NO CONFLICT. VISUAL CONDITIONS PREVAILED AND WE COULD SEE THE ARPT CLRLY. THESE ACFT ARE GETTING OLDER; AND THE VOLUME OF THESE 'NUISANCE WARNINGS' HAS INCREASED DRAMATICALLY. THESE ARE WARNINGS THAT GO OFF; INDICATING A PROBLEM; BUT THEN DISAPPEAR A FEW SECONDS LATER; LEAVING NO INDICATION THAT THE WARNING EVER EXISTED. ADDITIONALLY; MORE DILIGENT SCAN OF THE INSTRUMENTS DURING THE CRITICAL LEVELING OFF PHASE OF THE DSCNT WOULD HAVE AVOIDED THIS ISSUE ALSO.
Data retrieved from NASA's ASRS site as of January 2009 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.