Regional Jet 700 ER/LR (CRJ700)
Flight Crew Air Transport Pilot (ATP)
Other / Unknown
Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types
Air Traffic Control Issued New Clearance; Aircraft Equipment Problem Dissipated; Flight Crew Landed As Precaution; Flight Crew Diverted; General Declared Emergency; General Maintenance Action
Aircraft; Human Factors; Weather
At FL370 cruise received 'EFIS Comp Mon' caution with IAS and ALT flags on both left and right PFD's. Airspeed was indicating a decrease in speed approaching 200 knots. At this time left PFD did not have high speed or low speed 'tapes' present. Right PFD had both high and low speed 'tapes' displayed and converging. We began a descent and the airspeed continued to decrease with climb power set. The stick shaker activated in the descent with climb power set. The 'standby' instrument was also flagged and unreliable. During this event we encountered autopilot disconnect; rudder limit fault; mach trim disconnect; stall fail; and an anti-ice duct warning followed by an anti-ice caution.   Company Dispatch was contacted via SELCAL; emergency declared and we diverted to ZZZ without further issue.   1). The left and right PFD IAS and ALT flags cleared themselves while in the descent approximately at FL200 and appeared to be reliable at that time. The Standby instrument IAS flag never cleared and was present upon landing.  2). The QRH did not contain any solutions/guidance to the IAS/ALT situation since all three pitot systems were affected.  3). Upon landing; a contract Mechanic inspected the pitot system water traps and reported verbally to me that no water was present. The following day he stated that water was found; purged; and the system was signed off in the AML.
The reporter indicates that pitch and power were used to descend and maintain a safe flying speed. He does not recall if this procedure was taught at his current employer or a previous company.
CRJ700 Captain experiences an 'EFIS Comp Mon' caution with IAS and ALT flags on both left and right PFD's at FL370. In a descent with climb power set; stick shaker is activated and at the same time the standby instrument is noted to be flagged. Numerous other failures are indicated during the descent. Passing FL200 the left and right pitot static systems return to normal and the flight diverts to a suitable airport.