B737 FLT CREW IS QUESTIONED BY IAH CTLR REGARDING POS ON THE RWY AFTER BEING CLRED INTO POS. CTLR CONFUSION WITH CALL SIGNS DUE TO TFC VOLUME.

Narrative

WE FOLLOWED TAXI INSTRUCTIONS FROM SPOT 1 FOR WA TO WV TO RWY 15L. WHEN WE WERE NEXT IN LINE THE TWR CLRED US INTO POS AND HOLD WITH FULL READBACK BY US. DURING THIS TIME THE TWR OPERATOR SEEMED VERY BUSY. AFTER SEVERAL ACFT WERE CLRED FOR TKOF ON RWY 15R TWR CLRED AN ACR ACFT FOR TKOF ON OUR RWY. BEFORE WE ANSWERED HE AGAIN CLRED THE ACR FOR TKOF TO WHICH SOMEONE SAID 'WHO WAS THAT FOR?' THIS GOT THE TWR CTLR TO AGAIN CLR THE ACR FOR TKOF; TO WHICH THE ACR FLT REPLIED THAT HE WAS #3 IN LINE HOLDING SHORT OF RWY 15R. THE TWR CTLR THEN ASKED WHO WAS ON RWY 15L; AND THEN TOLD US 'I DIDN'T CLR YOU; BUT THAT IS OK; NO PROB.' HE THEN CLRED MORE ACFT FOR TKOF ON RWY 15R BEFORE CLRING US FOR TKOF ON RWY 15L. ABOUT THE TIME WE DEPARTED WE HEARD WHAT APPEARED TO BE ANOTHER MIX-UP AS TO 'WHO WAS ON FIRST.' THE TWR CTLR DID NOT SEEM TO HAVE A COMPLETE GRASP OF THE SIT; PERHAPS DUE TO HIS HVY WORKLOAD AT THE TIME. SUPPLEMENTAL INFO FROM ACN 621862: CLRLY THIS CTLR WAS CONFUSED AND HAD LOST SITUATIONAL AWARENESS AS TO WHERE ACFT WERE AND AT WHICH RWY. HE CLRLY STATED FOR US TO GO INTO POS AND WE READ THAT CLRNC BACK.