Small aircraft on IFR flight plan has ice building, unable maintain altitude.

Attributes
ACN	160907
Time
Date	199010
Day	Fri
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : bfd
State Reference	PA
Altitude	msl bound lower : 4000 msl bound upper : 4500
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tower : mht
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 2 Eng, Retractable Gear
Flight Phase	cruise other descent other
Route In Use	approach : circling enroute airway : v72
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 800
ASRS Report	160907
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 flight crewa
Resolutory Action	controller : issued new clearance flight crew : declared emergency
Consequence	Other
Supplementary
Primary Problem	Weather

Narrative:

Small aircraft westbound on V72 at 4500' MSL (filed 6000' MSL, requested lower due to ice). The initial letdown was requested 35 NM east of bfd, but was not executed for 15 NM. Ice was accumulating 1'/hour. I requested radar vectors to the nearest airport for landing. Cle asked if we would like bfd. The reply was yes. 2-5 mins later airspeed started fluctuating from 150 mph to 0 mph. I assumed it was pitot ice, but still advanced mixture propellers and throttle full. We descended to 4000' MSL to maintain red line and broke out below the overcast. 3 mi ahead was bfd rotating beacon. ZOB asked if we wanted an approach and I replied negative, 'we have bfd in sight,' and were going to circle left for runway 23. Center then advised us to change to CTAF. We landed safely and contacted the FSS on field.

Original NASA ASRS Text

Title: SMA ON IFR FLT PLAN HAS ICE BUILDING, UNABLE MAINTAIN ALT.

Narrative: SMA WBND ON V72 AT 4500' MSL (FILED 6000' MSL, REQUESTED LOWER DUE TO ICE). THE INITIAL LETDOWN WAS REQUESTED 35 NM E OF BFD, BUT WAS NOT EXECUTED FOR 15 NM. ICE WAS ACCUMULATING 1'/HR. I REQUESTED RADAR VECTORS TO THE NEAREST ARPT FOR LNDG. CLE ASKED IF WE WOULD LIKE BFD. THE REPLY WAS YES. 2-5 MINS LATER AIRSPD STARTED FLUCTUATING FROM 150 MPH TO 0 MPH. I ASSUMED IT WAS PITOT ICE, BUT STILL ADVANCED MIXTURE PROPS AND THROTTLE FULL. WE DSNDED TO 4000' MSL TO MAINTAIN RED LINE AND BROKE OUT BELOW THE OVCST. 3 MI AHEAD WAS BFD ROTATING BEACON. ZOB ASKED IF WE WANTED AN APCH AND I REPLIED NEGATIVE, 'WE HAVE BFD IN SIGHT,' AND WERE GOING TO CIRCLE LEFT FOR RWY 23. CENTER THEN ADVISED US TO CHANGE TO CTAF. WE LANDED SAFELY AND CONTACTED THE FSS ON FIELD.

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.