Air carrier flight crew reported experiencing central air data computer malfunction in heavy rain.

Attributes
ACN	1522592
Time
Date	201802
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	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	Air Data Computer
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter Weather / Turbulence

Narrative:

With first officer flying; on descent on [the] arrival in heavy rain; received IAS miscompare. Autopilot kicked off; received several level 2 alerts associated with CADC. Airspeed was 20 knots different between captain and first officer. Ran airspeed unreliable checklist and determined that first officer's airspeed was reliable. We [advised ATC] due to holding going on for other emergency. Transferred control and I flew an uneventful approach to landing on CADC 2 in heavy weather.heavy rain can overwhelm pitot static system in md (maintenance debrief). Continue to fly CADC failures in the simulator to keep aircrew sharp for dangerous scenarios such as this.

Original NASA ASRS Text

Title: Air carrier flight crew reported experiencing Central Air Data Computer malfunction in heavy rain.

Narrative: With First Officer flying; on descent on [the] arrival in heavy rain; received IAS Miscompare. Autopilot kicked off; received several Level 2 Alerts associated with CADC. Airspeed was 20 knots different between Captain and First Officer. Ran Airspeed Unreliable Checklist and determined that First Officer's airspeed was reliable. We [advised ATC] due to holding going on for other emergency. Transferred control and I flew an uneventful approach to landing on CADC 2 in heavy weather.Heavy rain can overwhelm pitot static system in MD (Maintenance debrief). Continue to fly CADC failures in the simulator to keep aircrew sharp for dangerous scenarios such as this.

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.