TKOF ABORTED AFTER AFT CARGO DOOR LIGHT COMES ON.

Narrative

ON TKOF ROLL AT APPROX 90 KTS MASTER CAUTION LIGHT ILLUMINATED; AFT CARGO DOOR LIGHT ILLUMINATED. ABORT WAS INITIATED AT 100-110 KTS. THROTTLES WERE CLOSED AND GENTLE BRAKING WAS INITIATED (9000 FT OF RWY REMAINING; OAT 20 DEG F). I CRACKED THE REVERSERS OUT OF HABIT AND WAS SURPRISED BY RTO MAX BRAKING AUTOBRAKES. AS THIS WAS A BENIGN 'OOPS; DON'T TKOF; GO BACK TO THE GATE' EVENT; NOT A PANIC MAX EFFORT EVENT; I HAD FORGOTTEN ABOUT THE AUTOBRAKES BEING SET AT 'RTO.' I TOLD THE FO TO TURN OFF THE AUTOBRAKES; WHICH HE DID IMMEDIATELY. MAX BRAKING WAS USED FOR ONLY 4-6 SECONDS; MAYBE LESS. RETURNED TO THE GATE; REPAIRS MADE AND BRAKES INSPECTED. THEY WERE QUITE WARM TO THE TOUCH; BUT NOT HOT. DISPATCH RELAYED THAT WE REQUIRED 55 MINS BRAKE COOLING DELAY. AS THESE CHARTS ARE PREDICATED ON MAX BRAKING FROM BRAKE INITIATION TO STOP; I TOLD THE AGENT TO DISREGARD AND WE PUSHED WHEN REPAIRS WERE COMPLETED. I WAS ADVISED BY CHIEF PLTS OFFICE TO SUBMIT NASA RPT AS FAA LOOKS ONLY AT BRAKE APPLICATION SPD WT; OAT; ETC AND ALLOWS NO PLT DISCRETION AS TO BRAKE COOLING TIME. WE PROBABLY COMPLIED WITH BRAKE COOLING TIME BECAUSE OF TIME REQUIRED FOR REPAIRS; POINT IS; FAA SHOULD ALLOW DISCRETION BY CREW WHO WAS THERE AND MAINT INSPECTION. SUPPLEMENTAL INFO FROM ACN 228274. TIME PERIOD WAS COMPLIED WITH AND BECAUSE OF TIME REQUIRED FOR REPAIRS ABORT OCCURRED AT AM45L AND SECOND TKOF WAS INITIATED AFTER PM00L.