Narrative:

While at cruise flight we received an 'EFIS comp mon' caution and a boxed amber IAS on the pfd. The first officer was the pilot flying and I was pilot not flying. I followed the QRH for those items; and when compared to the standby instruments; led us to determine that the captain side air data computer (air data computer 1) had failed. With ATC we initiated a descent to FL280 in compliance with the checklist (to exit rvsm airspace). Once we were at FL280 and out of the weather; my first officer noticed an increasing discrepancy between his airspeed and the standby airspeed. We were level; power set for cruise; and the airspeed on pfd 2 was bleeding off. At this point he stopped using the pfd and was relying on only the standby instruments. It became obvious that air data computer 2 was unreliable (airspeed on pfd 2 eventually got as low as 88 KIAS) and I ran the complete air data computer failure checklist. As per the checklist we determined the nearest suitable airport. We communicated with the dispatcher that we were diverting due to an air data problem. We declared an emergency with ATC and received direct the field. I informed the flight attendants of our problem; that we were diverting. A PA was then made describing our problem. After we turned toward the divert airport; it appeared that air data computer 2 made a recovery of some sort; and was then matching what the standby instruments were indicating. The first officer continued using the standby instruments until a visual approach and landing were made. The approach and landing were uneventful. The mechanic that inspected the pitot system stated that pitot systems 1 and 2 were approximately 30% full of water.the threats came in waves. The first threat was the thunderstorms that we were deviating around. After the problem began the threats were not only the air data computer 1; but now air data computer 2. Questions swirled in my head as to what exactly is the problem? Why are both air data computer's erroneous? That I must be missing something; the last threat was managing the communication with everyone - ATC; company; flight attendants; passengers - while keeping an eye on things. I think that I may have needed to 'stop and wind the clock'; or slow down and evaluate more.

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Original NASA ASRS Text

Title: A CRJ-700 experienced an apparent dual ADC failure inflight as first PFD1 then PFD2 airspeeds differed from the standby. The QRH was completed; an emergency was declared and the flight diverted but during descent the systems returned to normal. A Mechanic found both systems approximately 30% full of water.

Narrative: While at cruise flight we received an 'EFIS COMP MON' caution and a boxed amber IAS on the PFD. The First Officer was the pilot flying and I was pilot not flying. I followed the QRH for those items; and when compared to the standby instruments; led us to determine that the Captain side ADC (ADC 1) had failed. With ATC we initiated a descent to FL280 in compliance with the checklist (to exit RVSM airspace). Once we were at FL280 and out of the weather; my First Officer noticed an increasing discrepancy between his airspeed and the standby airspeed. We were level; power set for cruise; and the airspeed on PFD 2 was bleeding off. At this point he stopped using the PFD and was relying on only the standby instruments. It became obvious that ADC 2 was unreliable (airspeed on PFD 2 eventually got as low as 88 KIAS) and I ran the complete ADC Failure Checklist. As per the checklist we determined the nearest suitable airport. We communicated with the Dispatcher that we were diverting due to an air data problem. We declared an emergency with ATC and received direct the field. I informed the flight attendants of our problem; that we were diverting. A PA was then made describing our problem. After we turned toward the divert airport; it appeared that ADC 2 made a recovery of some sort; and was then matching what the standby instruments were indicating. The First Officer continued using the standby instruments until a visual approach and landing were made. The approach and landing were uneventful. The Mechanic that inspected the pitot system stated that pitot systems 1 and 2 were approximately 30% full of water.The threats came in waves. The first threat was the thunderstorms that we were deviating around. After the problem began the threats were not only the ADC 1; but now ADC 2. Questions swirled in my head as to what exactly is the problem? Why are BOTH ADC's erroneous? That I must be missing something; the last threat was managing the communication with everyone - ATC; Company; flight attendants; passengers - while keeping an eye on things. I think that I may have needed to 'stop and wind the clock'; or slow down and evaluate more.

Data retrieved from NASA's ASRS site 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.