GA small aircraft track deviation due ice accumulation on VOR antenna.

Attributes
ACN	103156
Time
Date	198901
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : hio
State Reference	OR
Altitude	msl bound lower : 6000 msl bound upper : 6000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zse
Operator	general aviation : instructional
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute airway : v165
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 30 flight time total : 231 flight time type : 100
ASRS Report	103156
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	inflight encounter : weather non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

I departed IFR from portland/hillsboro. Encountered light fog, then IMC conditions, proceeded on my assigned route (V165 to olympia VOR then to seattle/boeing field). At the end of climb to 6000' seattle center said I was off course, I thought I was still on course. I got a vector back to course that was about 40 degree. I then looked out at my wings with a flashlight and saw I had accumulated quite a lot of ice that explained why I was off course. I told center of my icing and got a lower altitude. Callback conversation with reporter revealed the following: the reporter had done a vot check before takeoff and the navigation error was less than 3 degree. Not enough to put the aircraft 6 mi off track as reported by ARTCC. Other members of flying club confirmed they had been exposed to the same problems in icing conditions.

Original NASA ASRS Text

Title: GA SMA TRACK DEVIATION DUE ICE ACCUMULATION ON VOR ANTENNA.

Narrative: I DEPARTED IFR FROM PORTLAND/HILLSBORO. ENCOUNTERED LIGHT FOG, THEN IMC CONDITIONS, PROCEEDED ON MY ASSIGNED ROUTE (V165 TO OLYMPIA VOR THEN TO SEATTLE/BOEING FIELD). AT THE END OF CLIMB TO 6000' SEATTLE CENTER SAID I WAS OFF COURSE, I THOUGHT I WAS STILL ON COURSE. I GOT A VECTOR BACK TO COURSE THAT WAS ABOUT 40 DEG. I THEN LOOKED OUT AT MY WINGS WITH A FLASHLIGHT AND SAW I HAD ACCUMULATED QUITE A LOT OF ICE THAT EXPLAINED WHY I WAS OFF COURSE. I TOLD CENTER OF MY ICING AND GOT A LOWER ALT. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE RPTR HAD DONE A VOT CHECK BEFORE TKOF AND THE NAV ERROR WAS LESS THAN 3 DEG. NOT ENOUGH TO PUT THE ACFT 6 MI OFF TRACK AS REPORTED BY ARTCC. OTHER MEMBERS OF FLYING CLUB CONFIRMED THEY HAD BEEN EXPOSED TO THE SAME PROBLEMS IN ICING CONDITIONS.

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.