Narrative:

20 mins prior to departure had adr #1 fault indicated in the switch and on the ECAM. Notified maintenance controller who contacted contract mechanic to troubleshoot system. Mechanic went through troubleshoot; reset and test sent by maintenance controller. Told mechanic that there was water in static ports found on preflight from wash the night before. Mechanic said that would not cause fault. He reset system and signed off the write-up. On taxi out; system faulted a second time. Contacted maintenance controller and returned to gate. Mechanic swapped adr #1 to #2 position for MEL relief. He retested adr and did llm check. After doing ddg procedures; engines were started at gate to check for failures at mechanic's request. MEL was added to new release. First officer #3 was selected on air data switch; adr #2 turned off and circuit breaker for angle of attach #2 (N-9) pulled and collared. Flaps #3 takeoff performed in accordance with MEL procedure. At 3500 ft after flap retraction passing green DOT (210 KTS); stall warning sounded; red barber pole jumped to 230 KTS indicating a flight control degradation to alternate law. Aircraft nose immediately lowered and wings leveled to accelerate above indicated stall speed. Immediate concern was whether airspeed accurate or not because of previous failure of adr. An immediate check of captain's pfd with first officer's pfd and backup airspeed all showed the same airspeed. ECAM message came up 'flight control alternate law-protections lost.' there were no failures indicates anywhere! A lights check to see if we were missing something turned up nothing. Emergency was declared and dispatch was called with maintenance controller for help. Completed ECAM and communication. Had long discussion with maintenance controller with no definite reason for the failure. Decided to divert to ZZZ2 for runway length and uncertainty about nature of failure. Every time aircraft turned; stall speed jumped to 240 KTS. Reviewed MEL to rechk procedures accomplished on ground. Reviewed communication divert procedures. Planned for approach to longest runway at ZZZ2 and requested crash fire rescue equipment equipment. Lowered gear at 2500 ft; turned off autoplt to see if there were other failures. Direct law was actuated by gear extension. Uneventful touchdown. Had rescue check for physical damage to aircraft and taxied to gate.

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Original NASA ASRS Text

Title: A320 FLT CREW HAS FAILURE OF THE AIR DATA REF UNIT DURING CLB; ACFT REVERTS TO ALTERNATE LAW AND STALL WARNING OCCURS. FLT CREW DECLARES EMER AND DIVERTS FOR LNDG.

Narrative: 20 MINS PRIOR TO DEP HAD ADR #1 FAULT INDICATED IN THE SWITCH AND ON THE ECAM. NOTIFIED MAINT CTLR WHO CONTACTED CONTRACT MECH TO TROUBLESHOOT SYS. MECH WENT THROUGH TROUBLESHOOT; RESET AND TEST SENT BY MAINT CTLR. TOLD MECH THAT THERE WAS WATER IN STATIC PORTS FOUND ON PREFLT FROM WASH THE NIGHT BEFORE. MECH SAID THAT WOULD NOT CAUSE FAULT. HE RESET SYS AND SIGNED OFF THE WRITE-UP. ON TAXI OUT; SYS FAULTED A SECOND TIME. CONTACTED MAINT CTLR AND RETURNED TO GATE. MECH SWAPPED ADR #1 TO #2 POS FOR MEL RELIEF. HE RETESTED ADR AND DID LLM CHK. AFTER DOING DDG PROCS; ENGS WERE STARTED AT GATE TO CHK FOR FAILURES AT MECH'S REQUEST. MEL WAS ADDED TO NEW RELEASE. FO #3 WAS SELECTED ON AIR DATA SWITCH; ADR #2 TURNED OFF AND CIRCUIT BREAKER FOR ANGLE OF ATTACH #2 (N-9) PULLED AND COLLARED. FLAPS #3 TKOF PERFORMED IN ACCORDANCE WITH MEL PROC. AT 3500 FT AFTER FLAP RETRACTION PASSING GREEN DOT (210 KTS); STALL WARNING SOUNDED; RED BARBER POLE JUMPED TO 230 KTS INDICATING A FLT CTL DEGRADATION TO ALTERNATE LAW. ACFT NOSE IMMEDIATELY LOWERED AND WINGS LEVELED TO ACCELERATE ABOVE INDICATED STALL SPD. IMMEDIATE CONCERN WAS WHETHER AIRSPD ACCURATE OR NOT BECAUSE OF PREVIOUS FAILURE OF ADR. AN IMMEDIATE CHK OF CAPT'S PFD WITH FO'S PFD AND BACKUP AIRSPD ALL SHOWED THE SAME AIRSPD. ECAM MESSAGE CAME UP 'FLT CTL ALTERNATE LAW-PROTECTIONS LOST.' THERE WERE NO FAILURES INDICATES ANYWHERE! A LIGHTS CHK TO SEE IF WE WERE MISSING SOMETHING TURNED UP NOTHING. EMER WAS DECLARED AND DISPATCH WAS CALLED WITH MAINT CTLR FOR HELP. COMPLETED ECAM AND COM. HAD LONG DISCUSSION WITH MAINT CTLR WITH NO DEFINITE REASON FOR THE FAILURE. DECIDED TO DIVERT TO ZZZ2 FOR RWY LENGTH AND UNCERTAINTY ABOUT NATURE OF FAILURE. EVERY TIME ACFT TURNED; STALL SPD JUMPED TO 240 KTS. REVIEWED MEL TO RECHK PROCS ACCOMPLISHED ON GND. REVIEWED COM DIVERT PROCS. PLANNED FOR APCH TO LONGEST RWY AT ZZZ2 AND REQUESTED CFR EQUIP. LOWERED GEAR AT 2500 FT; TURNED OFF AUTOPLT TO SEE IF THERE WERE OTHER FAILURES. DIRECT LAW WAS ACTUATED BY GEAR EXTENSION. UNEVENTFUL TOUCHDOWN. HAD RESCUE CHK FOR PHYSICAL DAMAGE TO ACFT AND TAXIED TO GATE.

Data retrieved from NASA's ASRS site as of January 2009 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.