A320 TOOK OFF WITH AN ECAM HOT BRAKE WARNING AT ORD.

Narrative

TOOK OFF WITH HOT BRAKE INDICATION. EXTENSIVE TAXI FROM RWY 22L FOR TKOF. LESS THAN 1 MIN PRIOR TO TKOF AND JUST PRIOR TO 'TAXI INTO POS AND HOLD RWY 22L; BE READY FOR AN IMMEDIATE;' WE GOT A MASTER CAUTION AND ECAM FOR HOT BRAKES. ESTIMATE SEEING 335 DEGS C FOR L OUTBOARD BRAKE WITH L INBOARD ABOUT 270 DEGS C -- THEN CLRED FOR IMMEDIATE TKOF. TOLD FO TO CONTINUE THE TKOF ROLL AND THAT WE WOULD DELAY GEAR RETRACTION TO HELP WITH BRAKE COOLING. ONCE AIRBORNE; AT A SAFE ALT (AFTER GEAR RETRACTION); WE COMPLETED THE ECAM. SUPPLEMENTAL INFO FROM ACN 584549: WE HAD A LONG TAXI OUT FROM GATE TO RWY 22L AT ORD. JUST AS THE TWR CLRED US; 'RWY 22L TAXI INTO POS AND HOLD; BE READY FOR IMMEDIATE TKOF' WE GOT A MASTER CAUTION INDICATION WITH AN ECAM FOR HOT BRAKES. THE HIGHEST TEMP I REMEMBER SEEING WAS 335 DEGS ON THE L OUTBOARD BRAKE. AT THIS TIME WE WERE CLRED FOR IMMEDIATE TKOF. THE CAPT INSTRUCTED US TO CONTINUE WITH THE TKOF ROLL AND THAT WE WOULD DELAY GEAR RETRACTION TO HELP WITH BRAKE COOLING. ONCE WE WERE AIRBORNE; AT A SAFE ALT; WE COMPLETED THE ECAM PROC AND RETRACTED THE GEAR ONCE THE BRAKE HAD COOLED. THE REMAINDER OF THE FLT WAS UNEVENTFUL.