Narrative:

While receiving radar vectors for sequencing at hpn, we received a RA on TCASII. WX was 4500' broken 5 mi haze. On an assigned heading of 140 degree at 2000' MSL and 5.6 mi DME south of hpn approach advised us of traffic close proximity approximately 9 O'clock, 1500' MSL 'altitude unverified.' our reply was neg contact 'we'll take a turn.' ny approach replied 'turn left heading 080 degree' at this point our traffic 'displayed' on TCASII as a solid cyan diamond indicating at our 9'10 O'clock position. This was known as 'proximate traffic' in TCASII lingo. Moments later TCASII reported a TA which turned into a RA and instructed us to 'descend, descend now.' at this point we're rolling out on 080 degree heading and initiating a descent. The TCASII RA dictated a 1500 FPM descent. The RA stopped as we approached 1600' MSL to be replaced by a 'ground proximity warning signal' (GPWS instructing us to 'terrain whoop whoop, pull up.' at this time we saw our traffic, a cabin class multi-engine turbo-propeller passing from left to right in a shallow climb less than 1/8 mi in front of us. We transmitted our actions and reasons to ny approach as we vacated 2000' MSL due to our RA. The PF and I discussed this situation after the flight concluded. I believe ATC was trying to turn us 'inside' of this tfcs path. However it appears that it was a bad turn based on our radius of turn and the projected flight path of this VFR traffic. What's interesting and we both agreed that when ATC assigned 080 degree heading, initially we didn't like how it looked on TCASII. It appears that we should have declined that clearance based on TCASII information. As flight crews became more familiar with TCASII and better able to interpret 'intruder or TAS' before they become ras, maybe it will be more obvious when to accept or decline an ATC clearance based on TCASII information.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR PLT TAKES EVASIVE ACTION TO MISS UNIDENTIFIED ACFT.

Narrative: WHILE RECEIVING RADAR VECTORS FOR SEQUENCING AT HPN, WE RECEIVED A RA ON TCASII. WX WAS 4500' BROKEN 5 MI HAZE. ON AN ASSIGNED HDG OF 140 DEG AT 2000' MSL AND 5.6 MI DME S OF HPN APCH ADVISED US OF TFC CLOSE PROX APPROX 9 O'CLOCK, 1500' MSL 'ALT UNVERIFIED.' OUR REPLY WAS NEG CONTACT 'WE'LL TAKE A TURN.' NY APCH REPLIED 'TURN L HDG 080 DEG' AT THIS POINT OUR TFC 'DISPLAYED' ON TCASII AS A SOLID CYAN DIAMOND INDICATING AT OUR 9'10 O'CLOCK POS. THIS WAS KNOWN AS 'PROXIMATE TFC' IN TCASII LINGO. MOMENTS LATER TCASII RPTED A TA WHICH TURNED INTO A RA AND INSTRUCTED US TO 'DSND, DSND NOW.' AT THIS POINT WE'RE ROLLING OUT ON 080 DEG HDG AND INITIATING A DSNT. THE TCASII RA DICTATED A 1500 FPM DSNT. THE RA STOPPED AS WE APCHED 1600' MSL TO BE REPLACED BY A 'GND PROX WARNING SIGNAL' (GPWS INSTRUCTING US TO 'TERRAIN WHOOP WHOOP, PULL UP.' AT THIS TIME WE SAW OUR TFC, A CABIN CLASS MULTI-ENG TURBO-PROP PASSING FROM L TO R IN A SHALLOW CLB LESS THAN 1/8 MI IN FRONT OF US. WE XMITTED OUR ACTIONS AND REASONS TO NY APCH AS WE VACATED 2000' MSL DUE TO OUR RA. THE PF AND I DISCUSSED THIS SITUATION AFTER THE FLT CONCLUDED. I BELIEVE ATC WAS TRYING TO TURN US 'INSIDE' OF THIS TFCS PATH. HOWEVER IT APPEARS THAT IT WAS A BAD TURN BASED ON OUR RADIUS OF TURN AND THE PROJECTED FLT PATH OF THIS VFR TFC. WHAT'S INTERESTING AND WE BOTH AGREED THAT WHEN ATC ASSIGNED 080 DEG HDG, INITIALLY WE DIDN'T LIKE HOW IT LOOKED ON TCASII. IT APPEARS THAT WE SHOULD HAVE DECLINED THAT CLRNC BASED ON TCASII INFO. AS FLT CREWS BECAME MORE FAMILIAR WITH TCASII AND BETTER ABLE TO INTERPRET 'INTRUDER OR TAS' BEFORE THEY BECOME RAS, MAYBE IT WILL BE MORE OBVIOUS WHEN TO ACCEPT OR DECLINE AN ATC CLRNC BASED ON TCASII INFO.

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.