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Pilot of M20K encountered icing conditions on an IFR pleasure flight in moderate to heavy turbulence. Suffered static port icing on normal source and lost altimeter. Utilizing alternate static source altimeter returned to normal function.
| Attributes | |
| ACN | 585249 |
| Time | |
| Date | 200306 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| State Reference | WY |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv.artcc |
| Operator | general aviation : personal |
| Make Model Name | M-20 K (231) |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level cruise : enroute altitude change |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | other |
| Function | flight crew : single pilot oversight : pic |
| Qualification | pilot : private pilot : instrument |
| Experience | flight time last 90 days : 36 flight time total : 1450 flight time type : 1161 |
| ASRS Report | 585249 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter : turbulence inflight encounter other non adherence : clearance other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : provided flight assist flight crew : returned to assigned altitude flight crew : overcame equipment problem flight crew : returned to intended or assigned course |
| Supplementary | |
| Problem Areas | Aircraft Weather Flight Crew Human Performance |
| Primary Problem | Weather |
Narrative:
Aircraft picked up light rime ice in clouds at 16000 ft. Requested descent to lower altitude (13000 ft) to escape ice conditions. Conditions were moderate to heavy turbulence in clouds. Altimeter readout was erratic and at some time apparently frozen or inoperative. Initially I thought the altimeter was defective and reported so to ATC. Conditions at this time were VFR, so requested permission to circle in descent. Turned on alternate static source and altimeter immediately returned to normal function. I had descended to 9500 ft, reported normal function of altimeter to ATC and climbed back to assigned altitude. I was not aware, prior to this, that what was apparently light rime icing would affect the static system of the aircraft. Because of this my first conclusion was that the altimeter was defective rather than inoperative due to ice blocking the static ports on the side of the aircraft.
Original NASA ASRS Text
Title: PLT OF M20K ENCOUNTERED ICING CONDITIONS ON AN IFR PLEASURE FLT IN MODERATE TO HVY TURB. SUFFERED STATIC PORT ICING ON NORMAL SOURCE AND LOST ALTIMETER. UTILIZING ALTERNATE STATIC SOURCE ALTIMETER RETURNED TO NORMAL FUNCTION.
Narrative: ACFT PICKED UP LIGHT RIME ICE IN CLOUDS AT 16000 FT. REQUESTED DSCNT TO LOWER ALT (13000 FT) TO ESCAPE ICE CONDITIONS. CONDITIONS WERE MODERATE TO HVY TURB IN CLOUDS. ALTIMETER READOUT WAS ERRATIC AND AT SOME TIME APPARENTLY FROZEN OR INOP. INITIALLY I THOUGHT THE ALTIMETER WAS DEFECTIVE AND RPTED SO TO ATC. CONDITIONS AT THIS TIME WERE VFR, SO REQUESTED PERMISSION TO CIRCLE IN DSCNT. TURNED ON ALTERNATE STATIC SOURCE AND ALTIMETER IMMEDIATELY RETURNED TO NORMAL FUNCTION. I HAD DSNDED TO 9500 FT, RPTED NORMAL FUNCTION OF ALTIMETER TO ATC AND CLBED BACK TO ASSIGNED ALT. I WAS NOT AWARE, PRIOR TO THIS, THAT WHAT WAS APPARENTLY LIGHT RIME ICING WOULD AFFECT THE STATIC SYS OF THE ACFT. BECAUSE OF THIS MY FIRST CONCLUSION WAS THAT THE ALTIMETER WAS DEFECTIVE RATHER THAN INOP DUE TO ICE BLOCKING THE STATIC PORTS ON THE SIDE OF THE ACFT.
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.