GA small aircraft enroute encounter with icing conditions, resulting in altitude deviation excursion...

Attributes
ACN	130512
Time
Date	198912
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : aoo
State Reference	PA
Altitude	msl bound lower : 4600 msl bound upper : 5300
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 120 flight time total : 1800
ASRS Report	130512
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course none taken : unable
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

En route from st thomas VOR to johnstown VOR, WX at johnstown started to go down--visibility 2 1/2 mi in snow showers. WX at pit on other side of mountain still good. WX at st thomas still VFR, but I didn't want to get stuck between clouds and mountains. Filed flight plan with aoo radio. Gave me ZNY WX advisory for ice. Aoo told me to contact nyc. Couldn't reach them. Aoo told me to call ZOB. Got a hold of them and climbed to 5000'. Tops in area were 9000'(?). Stayed at 5000' instead of trying to climb. Started picking up ice (light), and asked for and got 7000'. Had trouble maintaining 7000'. Went back down to 5000'. Airspeed froze over. Turbulence and ice caused me to wander from heading slightly and deviate from altitude. Altitude showed 4800' when center said 4600'. Possible partial blockage of static? Shot approach into aoo ILS 20 with 1' rime on wings and windshield froze over no. Airspeed with only defroster side clear (left side). Flying from right seat, my failure to climb immediately or find an alternate route south VFR caused the deviation in altitude, and if the ice built any faster, could have caused an accident.

Original NASA ASRS Text

Title: GA SMA ENROUTE ENCOUNTER WITH ICING CONDITIONS, RESULTING IN ALT DEVIATION EXCURSION FROM CLRNC ALT.

Narrative: ENRTE FROM ST THOMAS VOR TO JOHNSTOWN VOR, WX AT JOHNSTOWN STARTED TO GO DOWN--VISIBILITY 2 1/2 MI IN SNOW SHOWERS. WX AT PIT ON OTHER SIDE OF MOUNTAIN STILL GOOD. WX AT ST THOMAS STILL VFR, BUT I DIDN'T WANT TO GET STUCK BTWN CLOUDS AND MOUNTAINS. FILED FLT PLAN WITH AOO RADIO. GAVE ME ZNY WX ADVISORY FOR ICE. AOO TOLD ME TO CONTACT NYC. COULDN'T REACH THEM. AOO TOLD ME TO CALL ZOB. GOT A HOLD OF THEM AND CLBED TO 5000'. TOPS IN AREA WERE 9000'(?). STAYED AT 5000' INSTEAD OF TRYING TO CLB. STARTED PICKING UP ICE (LIGHT), AND ASKED FOR AND GOT 7000'. HAD TROUBLE MAINTAINING 7000'. WENT BACK DOWN TO 5000'. AIRSPD FROZE OVER. TURB AND ICE CAUSED ME TO WANDER FROM HDG SLIGHTLY AND DEVIATE FROM ALT. ALT SHOWED 4800' WHEN CENTER SAID 4600'. POSSIBLE PARTIAL BLOCKAGE OF STATIC? SHOT APCH INTO AOO ILS 20 WITH 1' RIME ON WINGS AND WINDSHIELD FROZE OVER NO. AIRSPD WITH ONLY DEFROSTER SIDE CLR (LEFT SIDE). FLYING FROM RIGHT SEAT, MY FAILURE TO CLB IMMEDIATELY OR FIND AN ALTERNATE ROUTE S VFR CAUSED THE DEVIATION IN ALT, AND IF THE ICE BUILT ANY FASTER, COULD HAVE CAUSED AN ACCIDENT.

Data retrieved from NASA's ASRS site as of August 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.

GA small aircraft enroute encounter with icing conditions, resulting in altitude deviation excursion from clearance altitude.