Narrative:

On descent; I was the pilot monitoring. The number 2 autopilot was engaged. We were on the arrival and deviating south of a cluster of thunderstorms. On descent; we were IMC and I detected no in-flight icing. I did notice very light ice crystals and very light precipitation in the descent. When the pilot flying went to selected speed in the descent; I noticed that my airspeed indicator (captain pfd) showed approximately 5 KTS lower than the blue selected target triangle. We quickly became busy with other descent duties; crossing altitudes; etc. On approach; while in selected speed; I noticed my airspeed decreasing on a stabilized approach. The captain pfd showed the airspeed approaching vls and then decreasing below vls. We did a crosscheck of the first officer and isis airspeed indications and determined that the captain airspeed indicator was incorrectthere were no ECAM faults or sts messages related to airspeed while in flight. I do recall a CAT lll single message during the approach. After determining that the captain airspeed was faulty; we switched the air data to captain on 3 and received normal airspeed indications on the captain pfd. Around 1500' to 1000' feet in visual conditions; I switched the air data momentarily back to norm for trouble shooting information. The captain airspeed was approximately 25 KTS low. I returned the switch to captain on 3 and a normal landing followed. After landing at approximately 80 KTS on rollout; we received an adr 1 fault on the ECAM. Appropriate log entry was made and the pilot flying (check airman) discussed the problem with maintenance. I went outside and had a mechanic secure a stand and thoroughly inspect the nose area. The nose area; sensors; pitot tubes; etc. Appeared normal. There was some moisture on the nose area just forward of the windscreen. We could not determine if the moisture came from melting ice or condensation from the cool metal interaction with the warm moist evening air. The fact that we had an airbus air data problem without in-flight fault indications should possibly warrant further investigation

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Original NASA ASRS Text

Title: A321 Captain experienced an airspeed indication anomaly during descent and approach in IMC. Switching ADR to Captain on 3 corrected the PFD airspeed indication problem.

Narrative: On descent; I was the pilot monitoring. The number 2 autopilot was engaged. We were on the arrival and deviating south of a cluster of thunderstorms. On descent; we were IMC and I detected no in-flight icing. I did notice very light ice crystals and very light precipitation in the descent. When the pilot flying went to selected speed in the descent; I noticed that my airspeed indicator (Captain PFD) showed approximately 5 KTS lower than the blue selected target triangle. We quickly became busy with other descent duties; crossing altitudes; etc. On approach; while in selected speed; I noticed my airspeed decreasing on a stabilized approach. The Captain PFD showed the airspeed approaching VLS and then decreasing below VLS. We did a crosscheck of the First Officer and ISIS airspeed indications and determined that the Captain airspeed indicator was incorrectThere were no ECAM faults or STS messages related to airspeed while in flight. I do recall a CAT lll single message during the approach. After determining that the Captain airspeed was faulty; we switched the air data to Captain on 3 and received normal airspeed indications on the Captain PFD. Around 1500' to 1000' feet in visual conditions; I switched the air data momentarily back to Norm for trouble shooting information. The Captain airspeed was approximately 25 KTS low. I returned the switch to Captain on 3 and a normal landing followed. After landing at approximately 80 KTS on rollout; we received an ADR 1 fault on the ECAM. Appropriate log entry was made and the pilot flying (Check Airman) discussed the problem with Maintenance. I went outside and had a mechanic secure a stand and thoroughly inspect the nose area. The nose area; sensors; pitot tubes; etc. appeared normal. There was some moisture on the nose area just forward of the windscreen. We could not determine if the moisture came from melting ice or condensation from the cool metal interaction with the warm moist evening air. The fact that we had an Airbus air data problem without in-flight fault indications should possibly warrant further investigation

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.