FLT CREW OF MD80 ENCOUNTER ANOTHER ACFT ON APCH TO IAH.

Narrative

WHILE BEING VECTORED FOR APCH; WE HAD ANOTHER AIRPLANE PASS CLOSE ABOVE US AND THEN CUT IN FRONT OF US ON THE APCH. ON DOWNWIND WE WERE ASKED TO KEEP SPD AT 250 KTS. WE WERE GIVEN A RATHER LATE CLRNC TO 2000 FT AND A LATE TURN TOWARD THE APCH. UPON LINING UP WITH THE APCH; WE HEARD; 'CLRED FOR APCH' AND ACKNOWLEDGED THE CLRNC. AT THAT TIME; WE SAW ANOTHER MD80 PASS HIGH AND IN FRONT OF US. IT PASSED THROUGH THE CTRLINE AND THEN BACK TO CUT IN FRONT OF US. WE RPTED THE OTHER AIRPLANE AND WERE TOLD TO MAINTAIN VISUAL SEPARATION; SLOW TO 150 KTS AND CALL TWR. WE CONFIGURED FOR LNDG. OUR INITIAL SEPARATION WAS ABOUT 1 MI; BUT SOON WIDENED TO 3 OR MORE MI. WE LANDED WITH NO FURTHER INCIDENT. UPON LNDG; THE PLT OF THE OTHER AIRPLANE MENTIONED A CALL SIGN MIX-UP. I WONDERED WHO MIXED UP; US OR HIM. I CALLED THE APCH CTL SUPVR. HE PULLED THE TAPES TO FIND THAT I HAD IN FACT ANSWERED THE OTHER AIRPLANE'S APCH CLRNC. HE SAID WHAT HAPPENED; WAS THAT HE HAD A NEW CTLR WORKING WHO GAVE US THE LATE DSCNT. THIS CREATED A 'HOLE' IN FRONT OF US AND HE FILLED IT WITH THE OTHER MD80. I GUESS I HAD EXPECTED AN APCH CLRNC SINCE WE WERE ON THE APCH AND NO ONE WAS IN FRONT OF US AT THE TIME. THE CTLR APPARENTLY HAD EXPECTED US TO MAKE A RAPID DSCNT FROM 6000 FT TO 2000 FT. I EXPLAINED THAT THE MD80 DOESN'T DSND VERY FAST AT 250 KTS.