NMAC AVERTED BY TCASII RA. OPPOSITE DIRECTION TFC AT CLRED TO ALT. EVASIVE ACTION DSCNT. SAME ASSIGNED ALT.

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WE WERE DEPARTING DCA AND CLBING TO AN ASSIGNED ALT OF 17000 FT. PASSING APPROX 13000 FT THE CTLR INSTRUCTED US TO MAINTAIN 14000 FT. AS I WAS SETTING THE ALT ALERT; I NOTICED AN ACFT ON THE TCASII APPROX 1000 FT ABOVE OUR CURRENT ALT. I BROUGHT THIS TO THE ATTN OF THE COPLT BUT WAS UNABLE TO QUESTION THE CTLR DUE TO CONGESTION ON THE FREQ. I THEN SUGGESTED TO THE COPLT THAT WE LEVEL OFF AT WHICH TIME WE RECEIVED A TFC ALERT ON THE TCASII. SHORTLY THEREAFTER; WE RECEIVED A RA ON THE TCASII TO DSND; WHICH WE FOLLOWED. AFTER A SHALLOW DSCNT; WE RECEIVED A 'CLR OF CONFLICT' FROM THE TCASII. WE THEN RESUMED OUR CLB TO 14000 FT. DURING ALL OF THIS WE WERE UNABLE TO CONTACT ATC DUE TO CONGESTION ON THE FREQ. AFTER WE WERE CLR; THE OTHER ACFT INVOLVED; ACR Y; A B737; ADVISED THE CTLR OF HIS NEED TO FOLLOW A RA ON HIS TCASII. I DID NOT RPT OUR RA RESPONSE ON THE FREQ BECAUSE: 1) ACR Y HAD RPTED IT; 2) THE CONGESTION ON THE FREQ; 3) OUR DEV WAS MINOR AND MOMENTARY AND; 4) I PERCEIVED THAT THE CTLR WAS AWARE OF HIS MISTAKE. IN RETROSPECT; I FEEL I SHOULD HAVE RPTED IT ON FREQ AS MY COPLT HAD SUGGESTED. A CONTRIBUTING FACTOR TO THIS INCIDENT WAS THE FACT THAT THE CTLR WAS APPARENTLY XMITTING TO ACFT ON 2 DIFFERENT FREQS. SUPPLEMENTAL INFO FROM ACN 346400: WE WOULD HAVE MOST LIKELY RUN INTO TFC HAD IT NOT BEEN FOR THE TCASII. TFC SEPARATION WAS REDUCED TO ABOUT 500 FT.