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Pilot of an small aircraft sel lost aircraft control while in icing conditions, and regaining aircraft control after losing 4000 ft of altitude.
| Attributes | |
| ACN | 324386 |
| Time | |
| Date | 199512 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : 057 |
| State Reference | CA |
| Altitude | msl bound lower : 12000 msl bound upper : 20000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa |
| Operator | general aviation : personal |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 40 flight time total : 1250 flight time type : 900 |
| ASRS Report | 324386 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | inflight encounter : weather other anomaly |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : provided flight assist flight crew : regained aircraft control flight crew : declared emergency flight crew : overcame equipment problem flight crew : exited adverse environment |
| Consequence | faa : reviewed incident with flight crew faa : investigated Other |
| Supplementary | |
| Primary Problem | Weather |
Narrative:
While in cruise on top of layer (high cirrus layer much farther above), we were engulfed by a rising and building cloud head. No icing was forecast. While within the cloud we were accumulating ice quickly on all leading edges and front windows. Pitot heat was on prior to entry of cloud. After about 90 seconds we had not exited the other side, we executed a 180 degree turn in an attempt to exit the icing conditions. Shortly after executing the turn, we lost indications of airspeed (140 to 0 indicated in about 15 seconds) as well as all other pitot-static instruments. Control of the aircraft was lost and we descended from 20000 ft to 16000 ft before control was regained. Emergency was declared during this time. We were still IMC when control was regained at 16000 ft but we had a moderate icing problem on the aircraft. We continued our controled descent below assigned altitudes and below MVA while being vectored toward mmh along airways. This was necessitated by the continued accumulation of ice. We broke out at 12300 ft over mono lake. While continuing our now VMC descent toward mammoth airport we partially lost power (probably due to induction ice up). Alternate air did little to restore full power. The windshield was completely frozen over. We landed safely at mmh by utilizing peripheral vision out of the side windows. The loss of control was due to fixation on the airspeed indicator problem and not properly xchking my other instruments. About 10 seconds elapsed between loss of control and the realization that a pitot-static blockage had occurred. I have practiced partial panel on my most recent instrument-comp check. Experiencing this failure in actual conditions and struggling to make sense of the instruments is quite different from an instructor obviously covering an instrument. I did not utilize the altitude-static valve, due to having to quickly handle the loss of control. I have received a crash (no pun intended) course in instrument failures in actual conditions. This was my first experience in such. The next time it happens I'll be much more prepared. I don't think fixation on any one instrument will occur again.
Original NASA ASRS Text
Title: PLT OF AN SMA SEL LOST ACFT CTL WHILE IN ICING CONDITIONS, AND REGAINING ACFT CTL AFTER LOSING 4000 FT OF ALT.
Narrative: WHILE IN CRUISE ON TOP OF LAYER (HIGH CIRRUS LAYER MUCH FARTHER ABOVE), WE WERE ENGULFED BY A RISING AND BUILDING CLOUD HEAD. NO ICING WAS FORECAST. WHILE WITHIN THE CLOUD WE WERE ACCUMULATING ICE QUICKLY ON ALL LEADING EDGES AND FRONT WINDOWS. PITOT HEAT WAS ON PRIOR TO ENTRY OF CLOUD. AFTER ABOUT 90 SECONDS WE HAD NOT EXITED THE OTHER SIDE, WE EXECUTED A 180 DEG TURN IN AN ATTEMPT TO EXIT THE ICING CONDITIONS. SHORTLY AFTER EXECUTING THE TURN, WE LOST INDICATIONS OF AIRSPD (140 TO 0 INDICATED IN ABOUT 15 SECONDS) AS WELL AS ALL OTHER PITOT-STATIC INSTS. CTL OF THE ACFT WAS LOST AND WE DSNDED FROM 20000 FT TO 16000 FT BEFORE CTL WAS REGAINED. EMER WAS DECLARED DURING THIS TIME. WE WERE STILL IMC WHEN CTL WAS REGAINED AT 16000 FT BUT WE HAD A MODERATE ICING PROB ON THE ACFT. WE CONTINUED OUR CTLED DSCNT BELOW ASSIGNED ALTS AND BELOW MVA WHILE BEING VECTORED TOWARD MMH ALONG AIRWAYS. THIS WAS NECESSITATED BY THE CONTINUED ACCUMULATION OF ICE. WE BROKE OUT AT 12300 FT OVER MONO LAKE. WHILE CONTINUING OUR NOW VMC DSCNT TOWARD MAMMOTH ARPT WE PARTIALLY LOST PWR (PROBABLY DUE TO INDUCTION ICE UP). ALTERNATE AIR DID LITTLE TO RESTORE FULL PWR. THE WINDSHIELD WAS COMPLETELY FROZEN OVER. WE LANDED SAFELY AT MMH BY UTILIZING PERIPHERAL VISION OUT OF THE SIDE WINDOWS. THE LOSS OF CTL WAS DUE TO FIXATION ON THE AIRSPD INDICATOR PROB AND NOT PROPERLY XCHKING MY OTHER INSTS. ABOUT 10 SECONDS ELAPSED BTWN LOSS OF CTL AND THE REALIZATION THAT A PITOT-STATIC BLOCKAGE HAD OCCURRED. I HAVE PRACTICED PARTIAL PANEL ON MY MOST RECENT INST-COMP CHK. EXPERIENCING THIS FAILURE IN ACTUAL CONDITIONS AND STRUGGLING TO MAKE SENSE OF THE INSTS IS QUITE DIFFERENT FROM AN INSTRUCTOR OBVIOUSLY COVERING AN INST. I DID NOT UTILIZE THE ALT-STATIC VALVE, DUE TO HAVING TO QUICKLY HANDLE THE LOSS OF CTL. I HAVE RECEIVED A CRASH (NO PUN INTENDED) COURSE IN INST FAILURES IN ACTUAL CONDITIONS. THIS WAS MY FIRST EXPERIENCE IN SUCH. THE NEXT TIME IT HAPPENS I'LL BE MUCH MORE PREPARED. I DON'T THINK FIXATION ON ANY ONE INST WILL OCCUR AGAIN.
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.