ATR72 flight crew experienced airframe anti-ice failure enroute and diverted to their filed alternat...

Narrative:

Enroute we had an airframe de-ice fault. The checklist was completed and we advised dispatch and maintenance of the need to avoid icing conditions. Our destination was reporting overcast skies and 3 degrees. The captain and I decided to divert and we asked dispatch to look for alternate destinations. ATC advised our filed alternate; looked best with VFR conditions and 11 degrees. We obtained a PIREP from a military aircraft for negative icing departing our filed alternate. Dispatch suggested another airport with overcast skied and -3 degrees. We informed dispatch and ATC of our intentions to divert to our filed alternate. 30 miles from the airport dispatch sent an ACARS expressing concerns of crosswind. We did not understand the concern since the field was VFR. Since dispatch had a safety concern that we could not address we took the most conservative course of action and declared an emergency with ATC. The flight landed uneventfully in our filed alternate. The event occurred due to a safety concern that could not be addressed due to our proximity. The safest course of action was to declare an emergency and land at since the weather was VFR.

Original NASA ASRS Text

Title: ATR72 flight crew experienced airframe anti-ice failure enroute and diverted to their filed alternate in order to avoid icing conditions. A low time Captain and communications issues add complexity to the scenario.

Narrative: Enroute we had an airframe de-ice fault. The checklist was completed and we advised Dispatch and maintenance of the need to avoid icing conditions. Our destination was reporting overcast skies and 3 degrees. The Captain and I decided to divert and we asked Dispatch to look for alternate destinations. ATC advised our filed alternate; looked best with VFR conditions and 11 degrees. We obtained a PIREP from a military aircraft for negative icing departing our filed alternate. Dispatch suggested another airport with overcast skied and -3 degrees. We informed Dispatch and ATC of our intentions to divert to our filed alternate. 30 miles from the airport Dispatch sent an ACARS expressing concerns of crosswind. We did not understand the concern since the field was VFR. Since Dispatch had a safety concern that we could not address we took the most conservative course of action and declared an emergency with ATC. The flight landed uneventfully in our filed alternate. The event occurred due to a safety concern that could not be addressed due to our proximity. The safest course of action was to declare an emergency and land at since the weather was VFR.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	837344
Time
Date	200905
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	ATR 72
Operating Under FAR Part	Part 121
Flight Phase	Cruise Descent
Flight Plan	IFR
Component
Aircraft Component	Aerofoil Ice System
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Commercial
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Inflight Event / Encounter Weather / Turbulence

ATR72 flight crew experienced airframe anti-ice failure enroute and diverted to their filed alternate in order to avoid icing conditions. A low time captain and communications issues add complexity to the scenario.