Narrative:

Descending through approximately 12500 MSL in idle power, 300 KIAS, on the dupont arrival into phl, we experienced a TCASII TA. TA was approximately 5 NM at 1 O'clock and 2000 below. I disconnected the autoplt and the first officer and I visually searched for traffic with no luck. At approximately 11500 MSL and 2 1/2 NM we got an RA to climb. I immediately advanced the power and initiated a 1 1/2 to 2 G pull-up into the green arc on the vvi. After climbing to approximately 12500 MSL, we got the 'clear of conflict' message and I resumed the descent to 10000 ft MSL as assigned, easily meeting all restrictions. Not until we received the RA and the first officer reported our maneuver to ZDC did we receive any traffic report from the controller. Neither pilot visually acquired the traffic but at the bottom of our maneuver, the RA was very close to the right wingtip of the airplane symbol on the 5 NM screen, and I recall minus 04 on the altitude readout. After landing in phl, passenger reported that, upon feeling our maneuver, he looked out and saw a twin turboprop with a high tail pass close enough that he could see both pilot's faces in the cockpit! Thank you TCASII!

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Original NASA ASRS Text

Title: AN ACR MLG HAD AN NMAC, OR LTSS, WITH A VFR SMT.

Narrative: DSNDING THROUGH APPROX 12500 MSL IN IDLE PWR, 300 KIAS, ON THE DUPONT ARR INTO PHL, WE EXPERIENCED A TCASII TA. TA WAS APPROX 5 NM AT 1 O'CLOCK AND 2000 BELOW. I DISCONNECTED THE AUTOPLT AND THE FO AND I VISUALLY SEARCHED FOR TFC WITH NO LUCK. AT APPROX 11500 MSL AND 2 1/2 NM WE GOT AN RA TO CLB. I IMMEDIATELY ADVANCED THE PWR AND INITIATED A 1 1/2 TO 2 G PULL-UP INTO THE GREEN ARC ON THE VVI. AFTER CLBING TO APPROX 12500 MSL, WE GOT THE 'CLR OF CONFLICT' MESSAGE AND I RESUMED THE DSCNT TO 10000 FT MSL AS ASSIGNED, EASILY MEETING ALL RESTRICTIONS. NOT UNTIL WE RECEIVED THE RA AND THE FO RPTED OUR MANEUVER TO ZDC DID WE RECEIVE ANY TFC RPT FROM THE CTLR. NEITHER PLT VISUALLY ACQUIRED THE TFC BUT AT THE BOTTOM OF OUR MANEUVER, THE RA WAS VERY CLOSE TO THE R WINGTIP OF THE AIRPLANE SYMBOL ON THE 5 NM SCREEN, AND I RECALL MINUS 04 ON THE ALT READOUT. AFTER LNDG IN PHL, PAX RPTED THAT, UPON FEELING OUR MANEUVER, HE LOOKED OUT AND SAW A TWIN TURBOPROP WITH A HIGH TAIL PASS CLOSE ENOUGH THAT HE COULD SEE BOTH PLT'S FACES IN THE COCKPIT! THANK YOU TCASII!

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.