Narrative:

Approximately 80-100 NM south [of destination] we experienced a #1 pitot heat failure. Within a minute a complete loss of the #1 a/south indicator (we were in IMC icing conditions/turbulence) this was followed by a string of other system failures due to the air data computer disagreement; which included an ADI mismatch message (802 panel); loss of both flight directors; loss of the yaw damper(s); loss of auto pilot; and a landing gear warning horn that could not be muted; that was intermittent. The first officer just happened to have the emergency check list out and was studying it. We got the caution light. I had him read the appropriate check list; we complied; system would not reset. We discussed the situation; picked up the ATIS. 070-6g15; SM RA br 200 ov.almost immediately; there was a 'water-fall' of issues due to this failure; supporting systems failing with the weather going down to boot. So we decided it prudent to declare an emergency. We contacted [ATC]; informed them and asked them to notify dispatch. We talked to the flight attendant and the passengers. ATC advised wind five knots and if we wanted [a longer runway]. We said great. Then closer they revised the wind back to 15 KTS. We opted to continue with [the long runway]; we had plenty of length; rather than being vectored another 10-15 minutes in icing and weather deteriorating and our present set of compound systems failure circumstances. Somewhere between 2;500 and 3;000 ft on the approach; we regained #1 a/south indication; heater was still failed; but ice melted. I was able to reengage the yaw damper for landing to. Runway made; we landed flaps 35. The flight concluded without further incident. Taxied to the gate; deplaned; talked to the fire department; called dispatch and made report; talked to maintenance; made write up and that was it.

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Original NASA ASRS Text

Title: A Dash-8; in cruise 80 NM south of destination; lost #1 pitot heat leading to the loss of several critical components. An emergency was declared.

Narrative: Approximately 80-100 NM south [of destination] we experienced a #1 Pitot Heat failure. Within a minute a complete loss of the #1 A/S Indicator (we were in IMC icing conditions/turbulence) this was followed by a string of other system failures due to the ADC disagreement; which included an ADI mismatch message (802 panel); loss of both Flight Directors; loss of the Yaw Damper(s); loss of Auto Pilot; and a Landing Gear Warning Horn that could not be muted; that was intermittent. The First Officer just happened to have the Emergency Check List out and was studying it. We got the caution light. I had him read the appropriate check list; we complied; system would not reset. We discussed the situation; picked up the ATIS. 070-6G15; SM RA BR 200 OV.Almost immediately; there was a 'water-fall' of issues due to this failure; supporting systems failing with the weather going down to boot. So we decided it prudent to declare an emergency. We contacted [ATC]; informed them and asked them to notify Dispatch. We talked to the Flight Attendant and the passengers. ATC advised wind five knots and if we wanted [a longer runway]. We said great. Then closer they revised the wind back to 15 KTS. We opted to continue with [the long runway]; we had plenty of length; rather than being vectored another 10-15 minutes in icing and weather deteriorating and our present set of compound systems failure circumstances. Somewhere between 2;500 and 3;000 FT on the approach; we regained #1 A/S indication; heater was still failed; but ice melted. I was able to reengage the Yaw Damper for landing to. Runway made; we landed flaps 35. The flight concluded without further incident. Taxied to the gate; deplaned; talked to the Fire Department; called Dispatch and made report; talked to Maintenance; made write up and that was it.

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.