A C-210's airspeed failed in IMC at 5;000 ft with the pitot heat on so the pilot declared an emergen...

Narrative:

After leveling in cruise and performing cruise checklist and filling [in] the data; the airspeed indicator very quickly dropped to zero. I immediately verified pitot heat was on and cross checked all the instruments to verify the aircraft was in level flight. Although no icing had been encountered; I also turned on the tks system since there was no airspeed indication to assist in detecting ice. I contacted departure and declared an emergency. I queried the controller about the weather conditions at my departure airport to minimize 'head down' time. I also queried the controller about the weather at my destination because in my pre-flight weather planning; the destination weather was forecast to be significantly better than the departure airport. I decided to continue the flight because the destination weather forecast was almost VFR compared to the departure which was almost low IFR and the aircraft was configured and trimmed to maintain straight and level flight. After several minutes; the airspeed came alive and the needle spun almost instantly from 0 to 160 KTS. I canceled the emergency with center and continued without any further issues with the indicator.

Original NASA ASRS Text

Title: A C-210's airspeed failed in IMC at 5;000 FT with the pitot heat ON so the pilot declared an emergency but continued because destination weather was near VFR. The airspeed recovered after a short time.

Narrative: After leveling in cruise and performing Cruise Checklist and filling [in] the data; the airspeed indicator very quickly dropped to zero. I immediately verified pitot heat was ON and cross checked all the instruments to verify the aircraft was in level flight. Although no icing had been encountered; I also turned on the TKS system since there was no airspeed indication to assist in detecting ice. I contacted Departure and declared an emergency. I queried the Controller about the weather conditions at my departure airport to minimize 'head down' time. I also queried the Controller about the weather at my destination because in my pre-flight weather planning; the destination weather was forecast to be significantly better than the departure airport. I decided to continue the flight because the destination weather forecast was almost VFR compared to the departure which was almost low IFR and the aircraft was configured and trimmed to maintain straight and level flight. After several minutes; the airspeed came alive and the needle spun almost instantly from 0 to 160 KTS. I canceled the emergency with Center and continued without any further issues with the indicator.

Data retrieved from NASA's ASRS site as of July 2013 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	1085055
Time
Date	201305
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	Cessna 210 Centurion / Turbo Centurion 210C 210D
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Airspeed Indicator
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Commercial
Events
Anomaly	Aircraft Equipment Problem Critical Inflight Event / Encounter Weather / Turbulence

A C-210's airspeed failed in IMC at 5;000 ft with the pitot heat on so the pilot declared an emergency but continued because destination weather was near VFR. The airspeed recovered after a short time.