A B727 FLC DEPARTED THE RWY SURFACE ONTO THE OVERRUN ON LNDG AT MSP.

Narrative

ACFT WAS DISPATCHED WITH ANTISKID INOP. FO WAS FLYING. WE LANDED SLIGHTLY LONG; ON SPD AND AS WE TOUCHED; A RAINSHOWER STARTED XING MIDFIELD. AT BRAKE APPLICATION; ACFT SEEMED TO HYDROPLANE; NOSE STARTED DRIFTING R (WIND 190 DEGS AT 13 KTS). I GOT ON CTLS WITH COPLT. OVERCORRECTED WITH TILLER TO L. ACFT WAS STILL HYDROPLANING AFTER RELEASE AND REAPPLICATION OF BRAKES. ACFT STOPPED ABOUT 100-150 FT PAST THRESHOLD. I ASKED TWR IF THIS WAS A LOAD-BEARING SURFACE. THEY THOUGHT SO AND SAID WE COULD TAXI BACK. I TURNED THE ACFT 180 DEGS BACK AND TAXIED OFF RWY. WE HAD MAINT CHK THE TIRES. THEY DISCOVERED 4 FLAT SPOTS (SUBSEQUENT TIRE CHANGES FOR ALL 4). I SHOULD HAVE STRESSED THE NEED TO TOUCH DOWN AT THE JET TOUCHDOWN BLOCKS RATHER THAN WORK THE SMOOTH TOUCHDOWN. THE HYDROPLANING REALLY TOOK US ALL BY SURPRISE. THERE WAS VERY LITTLE; IF ANY; DECELERATION AT BRAKE APPLICATION. AND I FEEL WE WERE REALLY LUCKY WE HAD AS MUCH RWY AS WE DID. MSP RWY 12L; 8200 FT. WE TOUCHED DOWN WITH AT LEAST 500 FT REMAINING (A MIL RESERVE UNIT HAS DISTRIBUTED REMAINING SIGNS ON THE RWY).