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Private pilot of an small aircraft twin, on a single pilot IFR flight, descended below assigned altitude while on autoplt hold causing him to quickly respond by manually returning the aircraft to assigned altitude.
| Attributes | |
| ACN | 386790 |
| Time | |
| Date | 199711 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : mkc |
| State Reference | MO |
| Altitude | msl bound lower : 4750 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : mci |
| Operator | general aviation : personal |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | Part 91 |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | other other : other pilot : private pilot : instrument |
| Experience | flight time last 90 days : 45 flight time total : 375 flight time type : 178 |
| ASRS Report | 386790 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Upon assigned descent to 5000 ft MSL activated autoplt altitude hold at 5000 ft MSL. The system did not actuate and aircraft deviated 200-250 ft below assigned altitude. The system error was recognized and corrected immediately (within a split second) by pilot with manual control. Correction was swift and autoplt system may not always respond to pressure altitude simultaneously. Must react manually for pitch control.
Original NASA ASRS Text
Title: PVT PLT OF AN SMA TWIN, ON A SINGLE PLT IFR FLT, DSNDED BELOW ASSIGNED ALT WHILE ON AUTOPLT HOLD CAUSING HIM TO QUICKLY RESPOND BY MANUALLY RETURNING THE ACFT TO ASSIGNED ALT.
Narrative: UPON ASSIGNED DSCNT TO 5000 FT MSL ACTIVATED AUTOPLT ALT HOLD AT 5000 FT MSL. THE SYS DID NOT ACTUATE AND ACFT DEVIATED 200-250 FT BELOW ASSIGNED ALT. THE SYS ERROR WAS RECOGNIZED AND CORRECTED IMMEDIATELY (WITHIN A SPLIT SECOND) BY PLT WITH MANUAL CTL. CORRECTION WAS SWIFT AND AUTOPLT SYS MAY NOT ALWAYS RESPOND TO PRESSURE ALT SIMULTANEOUSLY. MUST REACT MANUALLY FOR PITCH CTL.
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.