ACR X GAR DUE TO OCCUPIED RWY.

Narrative

ACR X BEING VECTORED BY ST LOUIS APCH FOR RWY 30L AT LAMBERT. APCH ASKED US IF WE HAD THE ARPT IN SIGHT. WE CONFIRMED WE HAD THE ARPT IN SIGHT. APCH POINTED OUT TFC ON A PARALLEL APCH FOR RWY 30R WHICH WE ALSO HAD IN SIGHT. APCH TOLD US TO DSND TO 2500 FT; TURN TO HDG 320 DEGS AND STARTED TO CLR US FOR THE APCH WHEN COM WAS LOST MID SENTENCE. IF WE CONTINUED ON THE 320 DEG HDG WE WOULD HAVE CONFLICTED WITH THE PARALLEL TFC. WE TRIED TWICE TO RE-ESTABLISH CONTACT WITH APCH WITH NO LUCK. I TURNED THE ACFT ON THE APCH TO AVOID A CONFLICT AND WE CALLED THE TWR THAT WE WERE ON THE APCH AND HE SAID 'CONTINUE.' WE CONTINUED THE APCH AND LEARNED THAT THE PROB WAS A B747 IN POS ON RWY 30L AND HAD SOME PAX GET OUT OF THEIR SEATS SO HE COULD NOT START HIS TKOF ROLL. TWR CALLED US AND SAID THIS WASN'T GOING TO WORK AND GAVE US A CLB TO 2500 FT AND A HDG FOR THE MISSED APCH. NO CONFLICT OCCURRED BUT LOOKING BACK ON THE SIT I AM NOT SURE THAT I SHOULD HAVE DEPARTED 2500 FT AND STARTED THE APCH. I BELIEVE THE REASON FOR THE LOST COM WAS THAT TWR WAS TALKING TO APCH ABOUT THE PROB WITH THE B747.