Narrative:

We were descending through roughly 20;000 ft after an uneventful flight. ATC had kept us high; so we were descending at a higher than normal airspeed and descent rate. No speed brakes were in use. The radar was on and returning no echoes. We flew into an IMC layer and then encountered very heavy rain and moderate turbulence. I reached down to turn on the engine ignition and when I looked up my airspeed indicator was behaving erratically. The excursions quickly grew to any range between mmo and vls. I disconnected the autopilot; confirmed that the first officer had reliable airspeed and gave control of the aircraft to him. We engaged autopilot 2. At this point my airspeed tape failed completely. There were many ECAM warnings. The first primary warning I believe was titled adr 1 [air data reference] unreliable. I do know that whatever the title was; no such wording was available in the QRH or supplemental manual. This condition lasted roughly 15-30 seconds; I believe. When we exited the rain all systems returned to normal. Because of the temporary failure the aircraft was now in alternate law. We ran the rest of the ECAM actions. I then became the pilot flying again as all my airspeed indications were fine and made an uneventful flaps 3 landing as directed by the ECAM. Once on the ground all systems were normal. I spoke with maintenance control and described what happened. Their thought; as was mine; was heavy rain in the number one pitot tube. We both agreed the aircraft was safe to return. Our flight back was uneventful.not sure of the cause but wanted to check if this aircraft had the pitot tube modification. Apparently it did. I am concerned with reference to the A330 accident that perhaps there are still things not understood about this situation.

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Original NASA ASRS Text

Title: An A321 Captain experienced an airspeed indication failure during descent through heavy rain. Control was transferred to the first Officer until the aircraft exited the rain when the Captains airspeed returned to normal. During the failure the aircraft reverted to Alternate Law and remained that way until landing.

Narrative: We were descending through roughly 20;000 FT after an uneventful flight. ATC had kept us high; so we were descending at a higher than normal airspeed and descent rate. No speed brakes were in use. The radar was on and returning no echoes. We flew into an IMC layer and then encountered very heavy rain and moderate turbulence. I reached down to turn on the engine ignition and when I looked up my airspeed indicator was behaving erratically. The excursions quickly grew to any range between MMO and Vls. I disconnected the autopilot; confirmed that the First Officer had reliable airspeed and gave control of the aircraft to him. We engaged autopilot 2. At this point my airspeed tape failed completely. There were many ECAM warnings. The first primary warning I believe was titled ADR 1 [Air Data Reference] unreliable. I do know that whatever the title was; no such wording was available in the QRH or Supplemental manual. This condition lasted roughly 15-30 seconds; I believe. When we exited the rain all systems returned to normal. Because of the temporary failure the aircraft was now in Alternate law. We ran the rest of the ECAM actions. I then became the pilot flying again as all my airspeed indications were fine and made an uneventful Flaps 3 landing as directed by the ECAM. Once on the ground all systems were normal. I spoke with Maintenance Control and described what happened. Their thought; as was mine; was heavy rain in the number one pitot tube. We both agreed the aircraft was safe to return. Our flight back was uneventful.Not sure of the cause but wanted to check if this aircraft had the pitot tube modification. Apparently it did. I am concerned with reference to the A330 accident that perhaps there are still things not understood about this situation.

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.