AN LGT CREW CLBED IN RESPONSE TO TCASII TO AVOID A WDB.

Narrative

WE WERE OPERATING FLT FROM EWR-MIA IN AN LGT WITH 142 PAXS ON BOARD. WE WERE LEVEL AT FL280. ZDC WAS ASKING ABOUT WHAT OUR MACH WOULD BE AT FL310. BEFORE I COULD REPLY; WE GOT A TA FOLLOWED BY AN IMMEDIATE RA ON THE TCASII WITH A 'CLB NOW' COMMAND. THE FO BEGAN A CLB. ATC CALLED OUT TFC AT 3 MI; 12 O'CLOCK AT FL270. I TOLD ATC WE WERE CLBING DUE TO A TCASII ALERT AND THE CTLR IMMEDIATELY ISSUED US A 30 DEG L TURN. THE FO SAW A WDB CLB OUT OF AN UNDERCAST AND PASS JUST OFF TO OUR R. ATC TOLD US THAT HE HAD RPTED LEVEL AT FL270. WE WERE AT 28900 AND WDB WAS STILL CLBING. PASSING WITHIN 5-700 FT OF US ACCORDING TO THE TCASII DISPLAY. WE THEN CLBED TO FL310 AND FLEW ON TO MIA. TCASII WAS ON LEVEL; 40 NM RING. THE FIRST DISPLAY WAS A RED ALERT WITHIN 5 NM OF OUR POS. IT APPEARS THAT THE WDB PROFESSIONALS WERE IN A FAIRLY STEEP CLB MODE THROUGH THEIR ASSIGNED ALT AND THEREBY GAVE OUR TCASII LITTLE CHANCE OF MUCH ADVANCED WARNING. THE ENTIRE SCENARIO LASTED 10-15 SECONDS. OUR CLB OUT OF FL280 TO AVOID A COLLISION WITH WDB CAUSED NO CONFLICT WITH ANY ADDITIONAL TFC ON THE AIRWAY.