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Reporter IFR encountered moderate mixed icing and had to descend below radar vector altitude to get into the clear and cancel IFR.
| Attributes | |
| ACN | 336948 |
| Time | |
| Date | 199605 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : pub |
| State Reference | CO |
| Altitude | msl bound lower : 15000 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv tower : cvg |
| Operator | general aviation : personal |
| Make Model Name | Cessna 210 Centurion / Turbo Centurion 210C, 210D |
| 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 pilot : cfi |
| Experience | flight time last 90 days : 15 flight time total : 800 flight time type : 800 |
| ASRS Report | 336948 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : weather other anomaly other |
| Independent Detector | other other : unspecified cockpit |
| Resolutory Action | flight crew : took evasive action flight crew : exited adverse environment |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Weather |
| Air Traffic Incident | other |
Narrative:
IFR assigned altitude of 17000 ft MSL in VFR conditions, with cloud ceiling below around 11000 ft MSL. I could see a diffuse cloud buildup approximately 20-30 mi directly ahead on the assigned route, but it did not appear to be a developing cell because of the diffused nature. Talked to ATC (ZDV) to determine what kind of rides had been reported through this area. ATC indicated that layers had been reported. I continued flight into the diffused clouds and within a short time (1-2 mins) had encountered moderate mixed icing. I called center to indicate I had to descend. I began my descent to 15000 ft MSL. Center indicated there was high terrain and the MVA was 16000 ft MSL. Upon reaching 15000 ft I had visual contact with the ground and indicated to center I was descending below the cloud base. After establishing VFR at around 12000 ft MSL I called center to cancel IFR and then continued VFR to dro. I am aware of icing in western united states around any cloud buildup at almost any time of yr. Here is what I will do in this situation in the future: 1) if I am VFR on an IFR flight plan and I see a cloud buildup which can be circumvented, I will immediately ask for a route deviation and if this cannot be obtained I will cancel IFR. 2) I will avoid even diffuse (undefined) buildups at any ht above 12000 ft MSL.
Original NASA ASRS Text
Title: RPTR IFR ENCOUNTERED MODERATE MIXED ICING AND HAD TO DSND BELOW RADAR VECTOR ALT TO GET INTO THE CLR AND CANCEL IFR.
Narrative: IFR ASSIGNED ALT OF 17000 FT MSL IN VFR CONDITIONS, WITH CLOUD CEILING BELOW AROUND 11000 FT MSL. I COULD SEE A DIFFUSE CLOUD BUILDUP APPROX 20-30 MI DIRECTLY AHEAD ON THE ASSIGNED RTE, BUT IT DID NOT APPEAR TO BE A DEVELOPING CELL BECAUSE OF THE DIFFUSED NATURE. TALKED TO ATC (ZDV) TO DETERMINE WHAT KIND OF RIDES HAD BEEN RPTED THROUGH THIS AREA. ATC INDICATED THAT LAYERS HAD BEEN RPTED. I CONTINUED FLT INTO THE DIFFUSED CLOUDS AND WITHIN A SHORT TIME (1-2 MINS) HAD ENCOUNTERED MODERATE MIXED ICING. I CALLED CTR TO INDICATE I HAD TO DSND. I BEGAN MY DSCNT TO 15000 FT MSL. CTR INDICATED THERE WAS HIGH TERRAIN AND THE MVA WAS 16000 FT MSL. UPON REACHING 15000 FT I HAD VISUAL CONTACT WITH THE GND AND INDICATED TO CTR I WAS DSNDING BELOW THE CLOUD BASE. AFTER ESTABLISHING VFR AT AROUND 12000 FT MSL I CALLED CTR TO CANCEL IFR AND THEN CONTINUED VFR TO DRO. I AM AWARE OF ICING IN WESTERN UNITED STATES AROUND ANY CLOUD BUILDUP AT ALMOST ANY TIME OF YR. HERE IS WHAT I WILL DO IN THIS SIT IN THE FUTURE: 1) IF I AM VFR ON AN IFR FLT PLAN AND I SEE A CLOUD BUILDUP WHICH CAN BE CIRCUMVENTED, I WILL IMMEDIATELY ASK FOR A RTE DEV AND IF THIS CANNOT BE OBTAINED I WILL CANCEL IFR. 2) I WILL AVOID EVEN DIFFUSE (UNDEFINED) BUILDUPS AT ANY HT ABOVE 12000 FT MSL.
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.