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An HS125-800 flew near a thunderstorm and lost air data computer's; autoplt; and attitude and heading. An emergency was declared with a VMC descent to a nearby airport.
| Attributes | |
| ACN | 713797 |
| Time | |
| Date | 200610 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | msl single value : 34000 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Turbulence Thunderstorm |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc artcc : svzm.artcc |
| Operator | general aviation : corporate |
| Make Model Name | BAe 125 Series 800 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : corporate |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : multi engine pilot : cfi |
| Experience | flight time last 90 days : 100 flight time total : 6000 flight time type : 1500 |
| ASRS Report | 713797 |
| Person 2 | |
| Affiliation | company : corporate |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical inflight encounter : turbulence inflight encounter : weather |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : landed as precaution flight crew : diverted to another airport flight crew : landed in emergency condition |
| Consequence | other |
| Supplementary | |
| Problem Areas | Weather Aircraft |
| Primary Problem | Weather |
Narrative:
In cruise at FL340 radar was showing a cell at our 10 O'clock position; and 15 mi. As soon as we encountered turbulence our autoplt disengaged and air data computer #1 and #2 failed along with attitude/heading #1 and #2 (ahrs #1 and #2) failures. Declared emergency and requested vectors away from thunderstorms. Using standby attitude indicator and altimeter we flew into an area of VFR conditions and made a rapid descent to avoid deteriorating WX in all quadrants. Maintained VFR below 23000 ft and requested vectors to nearest suitable airport. ZZZ was 35 mi and with VFR conditions. Landed safely. Resets of air data computer #1 and #2 circuit breakers; and checking for any failed busses was to no avail. Postflt showed no obvious lightning damage. Suspect electro-magnetic interference tripped our data bus #1 and #2 which caused a complete loss of data.
Original NASA ASRS Text
Title: AN HS125-800 FLEW NEAR A TSTM AND LOST ADC'S; AUTOPLT; AND ATTITUDE AND HDG. AN EMER WAS DECLARED WITH A VMC DSCNT TO A NEARBY ARPT.
Narrative: IN CRUISE AT FL340 RADAR WAS SHOWING A CELL AT OUR 10 O'CLOCK POS; AND 15 MI. AS SOON AS WE ENCOUNTERED TURB OUR AUTOPLT DISENGAGED AND ADC #1 AND #2 FAILED ALONG WITH ATTITUDE/HDG #1 AND #2 (AHRS #1 AND #2) FAILURES. DECLARED EMER AND REQUESTED VECTORS AWAY FROM TSTMS. USING STANDBY ATTITUDE INDICATOR AND ALTIMETER WE FLEW INTO AN AREA OF VFR CONDITIONS AND MADE A RAPID DSCNT TO AVOID DETERIORATING WX IN ALL QUADRANTS. MAINTAINED VFR BELOW 23000 FT AND REQUESTED VECTORS TO NEAREST SUITABLE ARPT. ZZZ WAS 35 MI AND WITH VFR CONDITIONS. LANDED SAFELY. RESETS OF ADC #1 AND #2 CIRCUIT BREAKERS; AND CHKING FOR ANY FAILED BUSSES WAS TO NO AVAIL. POSTFLT SHOWED NO OBVIOUS LIGHTNING DAMAGE. SUSPECT ELECTRO-MAGNETIC INTERFERENCE TRIPPED OUR DATA BUS #1 AND #2 WHICH CAUSED A COMPLETE LOSS OF DATA.
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.