Narrative:

At cruise; FL370; in IMC stall fail caution appeared briefly 3 or so times and would self-clear each time after a couple of seconds. Consulted QRH; message had cleared at this point. At this time we were deviating through and area of isolated thunderstorm the IMC conditions were partly the result of these cells as the 'tops' were dispersed in the upper FL300's. We were no closer than 10-15 NM of the cell cores at any time. Approximately 10 minutes later same stall fail caution scenario occurred except the stall fail caution remained posted. Per QRH we selected stall ptct pusher to off. Shortly thereafter stall fail caution self-cleared and with agreement of first officer; I decided that I was more comfortable turning the stall ptct switches back on we could apply QRH guidance again if stall fail caution returned (it did not). ATC advised we could expect holding for our filed destination and were given a clearance limit. We consulted our enroute chart to determine if a published holding pattern was depicted. Received holding instructions and were instructed that speed to our holding fix (approximately 40 NM ahead) was at our discretion. We began to slow. Soon after; stabilized at our new speed; in continuous light turbulence; the first officer noticed that the indicated airspeed on pfd 2 was continuing to show a slow decrease. Both pfd 1 and standby airspeed were stable relative to it; allowing for the continuous light turbulence. [I] directed the first officer to consult the QRH to assist with troubleshooting when EFIS comp mon caution posted. Applied the QRH guidance and concurred that we appeared to have an air data computer 2 failure. [We] selected air data source selector switch to air data computer 1. First officer reiterated the requirement to advise ATC of rvsm status. I noted it and said we would. Reviewing air data computer failure QRH procedure; as directed by QRH; we had brief discussion in relation to whether we had a single or a dual air data computer failure. Things started to happen quickly from this point. My recollection was that at this juncture we received a mach trim caution. I then observed that indicated airspeed on my pfd 1 was slowly degrading. I increased thrust; but indicated speed and trend vector maintained slow indicated decrease. Isi speed was steady. I selected climb power and told first officer to declare an emergency and advise that we would be descending. As captain's indicated speed on pfd 1 continued to degrade; the low speed cue began to appear. Isi indicated speed was stable. As we began descent with autopilot disengaged low speed cue and high speed cue quickly converged. The sticker shaker activated and stayed engaged for some time. I believe we were descending when we received the rudder limiter caution. [I] directed the first officer to consult that QRH procedure. I was concerned with rudder travel issues at altitude with an expedited; no mach trim and autopilot disengaged descent. IMC conditions still prevailed. First officer was exploring diversion airport options with ATC and backing me up. Soon after beginning descent isi speed began to decrease. We were in a descent with high power set. I asked the first officer if he would cross-check my analysis as I now felt that I could no longer rely upon my isi speed either. He agreed. I maintained my approximately 2.5 degree nose down attitude and rolled out on ATC assigned heading for a vector to a divert airport. With wings level I observed mfd ground speed indicating approximately 520 KTS. The first officer was busy so I think I notified him that I was going to reduce power. When his workload allowed I asked him to query ATC as to our ground speed. Their response was consistent with our ground speed readout at that time. Around this time we lost all air data computer display info on both pfd's (red flags for altitude; V/south and IAS). First officer pointed out that we might want to consider reselecting both position for air data computer's on source selector panel. Given the hope that we may recover at least one air data computer at some point and/or that we might have somehow misdiagnosed our problem I concurred. We had no usable air data computer data on either pfd at that point anyway. In the region of 24;000 ft or so isi airspeed seem to recover. Shortly thereafter pfd 1; then pfd 2 air data recovered. Consulting the isi; [I] asked the first officer to query ATC as to current ground speed. Isi indicated speed was more credible at this point. Assigned FL190 and descending through approximately FL210 we agreed that air data computer info for isi and pfd 1 appeared to be reliable but airspeed for pfd 2 was still indicating a 'slower' speed. We elected to deem pfd 2 info invalid and per QRH procedures selected pfd 1 data on the source selector panel. All other previous caution messages had self-cleared. At this point we felt confident enough to attempt to reengage the autopilot. Having initially chosen a nearby divert airport with ATC input as to weather conditions and runway length there and at a major regional airport; we revised our destination to the larger airport with updated weather now indicating no gusts and similar ceiling to the closer airport. [We] notified flight attendants of approximately 6 minutes to landing. We had initially notified them of our intention to divert earlier. First officer notified operations of our impending arrival and got a gate assignment. First officer made PA to passengers notifying them of our intention to divert. Remainder of flight was without further incident. Parked at what later transpired was a remote international gate. [We] assisted agent with passenger queries. Were led to a vacant customs quarantine area which necessitated 'rescue' by airport officials 25 minutes later. Returned to aircraft and followed-up with dispatch; notified maintenance control and contacted chief pilot on-call.

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Original NASA ASRS Text

Title: A CRJ-700 in IMC at FL370 lost all air data computer information; resulting in the loss of all altitude; indicated airspeed; and VSI indications. A diversion was made to a nearby airport and while descending through FL240; Air Data Computer 1 systems returned to normal.

Narrative: At cruise; FL370; in IMC Stall Fail Caution appeared briefly 3 or so times and would self-clear each time after a couple of seconds. Consulted QRH; message had cleared at this point. At this time we were deviating through and area of isolated thunderstorm the IMC conditions were partly the result of these cells as the 'tops' were dispersed in the upper FL300's. We were no closer than 10-15 NM of the cell cores at any time. Approximately 10 minutes later same Stall Fail Caution scenario occurred except the Stall Fail Caution remained posted. Per QRH we selected Stall PTCT Pusher to OFF. Shortly thereafter Stall Fail caution self-cleared and with agreement of First Officer; I decided that I was more comfortable turning the Stall PTCT switches back ON we could apply QRH guidance again if Stall Fail Caution returned (it did not). ATC advised we could expect holding for our filed destination and were given a clearance limit. We consulted our enroute chart to determine if a published holding pattern was depicted. Received holding instructions and were instructed that speed to our holding fix (approximately 40 NM ahead) was at our discretion. We began to slow. Soon after; stabilized at our new speed; in continuous light turbulence; the First Officer noticed that the indicated airspeed on PFD 2 was continuing to show a slow decrease. Both PFD 1 and Standby Airspeed were stable relative to it; allowing for the continuous light turbulence. [I] directed the First Officer to consult the QRH to assist with troubleshooting when EFIS COMP MON caution posted. Applied the QRH guidance and concurred that we appeared to have an ADC 2 failure. [We] selected Air Data source selector switch to ADC 1. First Officer reiterated the requirement to advise ATC of RVSM status. I noted it and said we would. Reviewing ADC Failure QRH procedure; as directed by QRH; we had brief discussion in relation to whether we had a single or a dual ADC failure. Things started to happen quickly from this point. My recollection was that at this juncture we received a MACH TRIM Caution. I then observed that indicated airspeed on my PFD 1 was slowly degrading. I increased thrust; but indicated speed and trend vector maintained slow indicated decrease. ISI speed was steady. I selected climb power and told First Officer to declare an emergency and advise that we would be descending. As Captain's indicated speed on PFD 1 continued to degrade; the low speed cue began to appear. ISI indicated speed was stable. As we began descent with autopilot disengaged low speed cue and high speed cue quickly converged. The sticker shaker activated and stayed engaged for some time. I believe we were descending when we received the Rudder Limiter Caution. [I] directed the First Officer to consult that QRH procedure. I was concerned with rudder travel issues at altitude with an expedited; no Mach Trim and autopilot disengaged descent. IMC conditions still prevailed. First Officer was exploring diversion airport options with ATC and backing me up. Soon after beginning descent ISI speed began to decrease. We were in a descent with high power set. I asked the First Officer if he would cross-check my analysis as I now felt that I could no longer rely upon my ISI speed either. He agreed. I maintained my approximately 2.5 degree nose down attitude and rolled out on ATC assigned heading for a vector to a divert airport. With wings level I observed MFD ground speed indicating approximately 520 KTS. The First Officer was busy so I think I notified him that I was going to reduce power. When his workload allowed I asked him to query ATC as to our ground speed. Their response was consistent with our ground speed readout at that time. Around this time we lost all ADC display info on both PFD's (red flags for ALT; V/S and IAS). First Officer pointed out that we might want to consider reselecting BOTH position for ADC's on source selector panel. Given the hope that we may recover at least one ADC at some point and/or that we might have somehow misdiagnosed our problem I concurred. We had no usable ADC data on either PFD at that point anyway. In the region of 24;000 FT or so ISI airspeed seem to recover. Shortly thereafter PFD 1; then PFD 2 air data recovered. Consulting the ISI; [I] asked the First Officer to query ATC as to current ground speed. ISI indicated speed was more credible at this point. Assigned FL190 and descending through approximately FL210 we agreed that ADC info for ISI and PFD 1 appeared to be reliable but airspeed for PFD 2 was still indicating a 'slower' speed. We elected to deem PFD 2 info invalid and per QRH procedures selected PFD 1 data on the Source Selector panel. All other previous caution messages had self-cleared. At this point we felt confident enough to attempt to reengage the autopilot. Having initially chosen a nearby divert airport with ATC input as to weather conditions and runway length there and at a major regional airport; we revised our destination to the larger airport with updated weather now indicating no gusts and similar ceiling to the closer airport. [We] notified flight attendants of approximately 6 minutes to landing. We had initially notified them of our intention to divert earlier. First Officer notified Operations of our impending arrival and got a gate assignment. First Officer made PA to passengers notifying them of our intention to divert. Remainder of flight was without further incident. Parked at what later transpired was a remote international gate. [We] assisted Agent with passenger queries. Were led to a vacant Customs quarantine area which necessitated 'rescue' by airport officials 25 minutes later. Returned to aircraft and followed-up with Dispatch; notified Maintenance Control and contacted Chief Pilot on-call.

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.