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A light 2 turbojet transport on start of descent at FL330 experienced the left air data computer failure with associated instruments.
| Attributes | |
| ACN | 485259 |
| Time | |
| Date | 200009 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : pdk.airport |
| State Reference | GA |
| Altitude | msl single value : 33000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl.artcc |
| Operator | general aviation : corporate |
| Make Model Name | Light Transport, Low Wing, 2 Turbojet Eng |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | other |
| Flight Phase | descent : vacating altitude |
| Route In Use | arrival star : awson arrival enroute airway : j43.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : corporate |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 40 flight time total : 7500 flight time type : 2000 |
| ASRS Report | 485259 |
| Person 2 | |
| Affiliation | company : corporate |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : multi engine pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : #2 air data computer other flight crewa other flight crewb other other : person 3 |
| Resolutory Action | flight crew : overcame equipment problem |
| Consequence | other |
| Supplementary | |
| Problem Areas | Aircraft ATC Human Performance Flight Crew Human Performance |
| Primary Problem | Aircraft |
Narrative:
In level flight air data computer began to make mach/IAS, ivsi and altimeter erratic +/-800 ft, +/-.2 mach, +/-1000 FPM. Aircraft never left altitude per copilot side instrument which were working normal. Removed and replaced air data computer and aircraft is functioning normally. I flew the aircraft manually to eliminate altitude excursions that the aircraft would have done had autoplt been connected. ATC asked our altitude which was reported at FL330, where we were according to accurate copilot instrument.
Original NASA ASRS Text
Title: A LIGHT 2 TURBOJET TRANSPORT ON START OF DSCNT AT FL330 EXPERIENCED THE L AIR DATA COMPUTER FAILURE WITH ASSOCIATED INSTS.
Narrative: IN LEVEL FLT AIR DATA COMPUTER BEGAN TO MAKE MACH/IAS, IVSI AND ALTIMETER ERRATIC +/-800 FT, +/-.2 MACH, +/-1000 FPM. ACFT NEVER LEFT ALT PER COPLT SIDE INST WHICH WERE WORKING NORMAL. REMOVED AND REPLACED AIR DATA COMPUTER AND ACFT IS FUNCTIONING NORMALLY. I FLEW THE ACFT MANUALLY TO ELIMINATE ALT EXCURSIONS THAT THE ACFT WOULD HAVE DONE HAD AUTOPLT BEEN CONNECTED. ATC ASKED OUR ALT WHICH WAS RPTED AT FL330, WHERE WE WERE ACCORDING TO ACCURATE COPLT INST.
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.