POTENTIAL CONFLICT LTSS.

Narrative

I WAS CAPT ON FLT ON MAR/93 FROM MCO-PHL. AT ABOUT 42 MI S OF SIE VOR; WE WERE CLRED TO DSND FROM FL280(?) TO CROSS 25 MI S OF SIE VOR AT 15000. THIS; OF COURSE; REGAINED A VERY HIGH RATE OF DSCNT. WE COMPLIED WITH THE CLRNC. AT 25 MI S OF SIE VOR; WE WERE CHANGED TO FREQ 127.7. WHEN WE CHKED IN; THE CTLR CLRED US TO DSND TO 13000 FT. I REPEATED THE CLRNC AND THE FO WHO WAS FLYING THE ACFT STARTED DOWN. THE CTLR THEN TOLD US TO MAINTAIN 15000 FT. I TOLD HIM WE WERE ALREADY AT 14300 FT. THE CTLR THEN TOLD ANOTHER ACFT TO INCREASE HIS RATE OF DSCNT. HE THEN TOLD MY FLT TO FLY AN EASTERLY HDG. I REPEATED THE HDG CLRNC AND TOLD HIM WE WERE AT 14000 FT (THE ALT I HAD TOLD THE FO TO MAINTAIN UNTIL I UNDERSTOOD FOR SURE WHAT THE CTLR WANTED). WE WERE CLRED TO 15000 FT WHICH WE COMPLIED WITH. I THEN ASKED THE CTLR IF THERE HAD BEEN A CONFLICT. HE SAID THAT THERE HAD BEEN; THAT HE HAD MISTAKENLY CLRED US TO 13000 FT AND TRIED TO CANCEL THE CLRNC BUT WE HAD NOT HEARD IT. I CAN ONLY SUGGEST THAT WHEN THERE IS A TFC CONFLICT; THE CTLR SHOULD USE LANGUAGE SUCH AS: XXX; CLB OR DSND IMMEDIATELY; SO THERE CAN BE NO DOUBT AS TO WHAT IS WANTED.