A330 ECAM INDICATED 'REAR CARGO DOOR' WARNING DURING CLIMBOUT. FLT CREW RETURNED TO DEP ARPT AND LANDED OVERWEIGHT.

Narrative

CLBING THROUGH FL270; ECAM MESSAGE 'REAR CARGO DOOR.' ACFT LEVELED OFF AT FL275. COMPLIED WITH ECAM (WE THOUGHT). ECAM SHOULD HAVE SAID 'IF ABN CAB V/S MAX FL-100 MEA.' STATUS PAGE SAID; 'MAX FL-100/MEA.' WE SAW THE STATUS PAGE; BUT DID NOT SEE THE 'IF ABN CAB V/S' INFO. WE DID APPEAR TO HAVE NORMAL CABIN PRESSURE; HOWEVER FO HAD PULLED OUT OXYGEN MASK. HE THOUGHT THERE WAS A PRESSURE BUMP; BUT DID NOT PUT ON MASK. CONSIDERING 3+ HR FLT OVERWATER; WE DECIDED TO RETURN TO ZZZ. ESTIMATED LNDG WT OF 430000 LBS; MAX LNDG WT 412200 LBS. REFED OVERWT LNDG CHKLIST. CHKLIST NOTE 'PERFORM AN OVERWT LNDG WHEN A CONDITION CAUSES IT TO BE SAFER TO LAND OVERWT THAN THE CONTINUE FLT UNTIL AT OR BELOW MAX CERTIFICATED LNDG WT.' PLANNED LNDG ZZZ; RWY 10506 FT; QRH INDICATED 5940 FT REQUIRED. BY SATCOM; I DISCUSSED ALTERNATIVES WITH DISPATCH AND MAINT CTL. WE ALL AGREED TO LAND OVERWT AND NOT HOLD FOR 1 1/2-2 HRS TO BURN DOWN TO MAX LNDG WT. RETURNED TO ZZZ. AFTER BRAKES COOLED; RETURNED TO GATE. MAX BRAKE TEMP 580 DEGS. OUR PLT HANDBOOK HAS A CHAPTER WHICH IS A DETAILED VERSION OF THE ECAM FOR NON-NORMAL PROCS. IT IS 210 PAGES LONG AND STATES; 'AFTER PERFORMING THE ECAM ACTIONS AND REVIEWING ECAM STATUS; REFER TO THE PLT'S HANDBOOK PROC FOR SUPPLEMENTAL INFO IF TIME PERMITS.' ON THIS PAGE FOR THE CARGO DOOR OPEN; A NOTE SAYS; 'INFLT -- NO CREW ACTION REQUIRED AS LONG AS CABIN PRESSURE IS NORMAL.' THIS IS NOT ANNOTATED ON ECAM. WE WERE ATTEMPTING TO COMPLY WITH ECAM STATUS PAGE; DSNDING TO FL100; BEFORE EVER GETTING TO THIS CHAPTER. CHIEF PLT REQUESTED A MEETING WITH THE FLT CREW TO DISCUSS FLT; WITH UNION REPRESENTATIVES THE NEXT DAY. HE DID NOT AGREE WITH OUR RETURN TO ZZZ AND OUR DECISION TO LAND OVERWT. WE WERE GIVEN TRAINING IN ECAM USAGE AT THIS TIME BY A CHK AIRMAN. MY CONCERNS ARE: 1) DOES IT MAKE ANY SENSE TO CONTINUE A FLT WITH AN UNKNOWN CARGO DOOR PROB ON AN ETOPS FLT JUST BECAUSE AIRBUS SAYS IT'S OK; ESPECIALLY WHEN YOU ARE ONLY 25 MINS INTO THE FLT? 2) CRM IS STRESSED EXTENSIVELY IN OUR TRAINING AND THAT INCLUDES WITH DISPATCH AND MAINT CTL. ALL 3 AGREED ON THE OVERWT LNDG. THEN WE WERE ALL BEING SECOND GUESSED BY THE CHIEF PLT. NOTE: AS MEETING CONCLUDED; CHIEF PLT WAS NOTIFIED THE SAME ACFT; SAME FLT NUMBER; WITH THE SAME CARGO DOOR INDICATION; HAD JUST LANDED IN ZZZ AND MADE AN OVERWT LNDG. MAINT COMPLIED WITH CARGO DOOR MEL; WHICH INHIBITS THE DOOR WARNING. SAME ACFT DEPARTED ONCE MORE; SAME FLT NUMBER. EVEN THOUGH THE DOOR WARNING HAD PRESUMABLY BEEN DISABLED; THE WARNING CAME ON ONCE AGAIN! ACFT ONCE AGAIN RETURNED TO ZZZ WITH AN OVERWT LNDG.