SIMILAR CALL SIGNS AND CLB CLRNC CONFUSION RESULT IN TFC CONFLICT W OF LDN VOR; VA.

Narrative

DURING DEP FROM IAD; ACR FLT XYZ WAS CLRED TO 14000 FT IN THE VICINITY OF LINDON VOR. WE WERE LEVEL AT 14000 FT FOR SEVERAL MINS WHEN CTR SAID; 'ACR XYZ EXPEDITE CLB THROUGH 15000 FT.' I RESPONDED; 'ACR XYZ; WAS ONLY CLRED TO 14000 FT.' I ALSO HAD NOTICED THAT TFC AHEAD AT 15000 FT WAS CLOSING AND I FIGURED THAT WAS WHY WE WERE ONLY CLRED TO 14000 FT. CTR RESPONDED; 'ACR XYZ CLB TO 17000 FT; EXPEDITE THROUGH 15000 FT.' I RESPONDED 'ACR XYZ CLB TO 17000 FT AND SMARTLY THROUGH 15000 FT.' I FELT THAT THE TFC AHEAD AT 15000 FT COULD BE A HAZARD BUT THE FACT THAT CTR STRESSED EXPEDITE MEANT THAT SAFETY REQUIRED THE CLB. I SET THE ALT WINDOW TO 17000 FT; THE FO CONFIRMED THE ALT AND HE STARTED TO CLB. AFTER WE CLBED APPROX 100-200 FT THE TCASII TARGET TURNED FROM WHITE TO YELLOW AND I TOLD THE FO TO 'PUT THE NOSE DOWN; I DON'T LIKE THIS.' THEN WE GOT A DSND RA. WE WERE ALREADY LOWERING THE NOSE AND THE FO FOLLOWED THE GUIDANCE ON THE VERT SPD SCALE. WHILE ALL THIS WAS HAPPENING I HAD VISUAL CONTACT WITH THE TFC AND SAW HIM PASS OVERHEAD AS WE WERE LEVELING AT 14000 FT. THE RA HAD CEASED. ABOUT THIS TIME AND FOR THE FIRST TIME I WAS AWARE; ANOTHER ACR XYZ SAID SOMETHING TO CTR; AND CTR SAID SOMETHING LIKE; 'OTHER ACR XYZ NOT YOU.' CTR AGAIN AFTER A SHORT TIME CLRED US TO 17000 FT. CTR DID NOT SAY ANYTHING ABOUT WHAT HAD HAPPENED AND WE DIDN'T ASK. NEITHER THE FO OR I WERE CLR WHERE THE BREAKDOWN OCCURRED. I DID FEEL HOWEVER THAT I SHOULD HAVE QUESTIONED THE CLB CLRNC REGARDING THE TFC AHEAD.