Narrative:

Approximately 15 NM north of kingston VOR (ign), ZBW 128.1 MHZ gave us clearance to cross valre intersection at 9000 ft. I (first officer, PF) dialed 9000 into the altitude alerter (PF does this as procedure when autoplt is engaged). Captain was off the radio talking to the passenger briefly on PA system, so I read back the clearance. After reading back the clearance of 9000 and the controller acknowledged this, I recalled most clrncs on previous flts were to cross valre at 10000 (this is depicted on the extol 1 arrival chart into lga, but our company filed routing did not include this STAR). About a min after given the original clearance to 9000, I asked bos to re- confirm cross valre at 9000. He did. By this time captain was back on the radio and also heard valre at 9000. Crossing over kingston VOR (ign) tracking VI57 sbound we were approaching 10000 when TCASII gave us an RA command 'climb, climb.' RA on scope was minus 500 at 11 O'clock less than 2 mi. Vsi presentation displayed a few green dots between plus 1500 and plus 2000 FPM climb. The rest of the display showed red dots (TCASII working as designed!) I disengaged autoplt and smoothly but firmly raised nose to achieve 2000 FPM climb and added climb power. Captain notified ATC of RA and that we were climbing due to TCASII RA. ATC notified us of traffic and captain visually picked up the ATR commuter aircraft at 11 O'clock low, which captain said looked like a ATR turbo propeller. ZBW told us the traffic was squawking 1200 (VFR code) at 9500 ft and ATC was not working him. I later called ZBW on the telephone that same day and spoke with this controller. He indicated that they have a written letter from ny approach control that inbound aircraft must be at 9000 ft, 40 NM northwest of deer park VOR (dpk). I stated that the current extol 1 arrival plate states 'expect to cross valre at 10000.' the controller said they (FAA) will change this too. He earlier stated that 'many commuter aircraft routinely fly VFR at 9500 ft in this area.' I suggested that it would be safer to keep inbound aircraft at least at 10000 ft until south of kingston VOR before clearing them to descend to 9000. He said he would pass along the suggestion to his supervisor. I feel without the advance warning given to us by TCASII, we would have come very close to colliding with this commuter.

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Original NASA ASRS Text

Title: ACR IN DSCNT HAS TCASII RA TO CLB.

Narrative: APPROX 15 NM N OF KINGSTON VOR (IGN), ZBW 128.1 MHZ GAVE US CLRNC TO CROSS VALRE INTXN AT 9000 FT. I (FO, PF) DIALED 9000 INTO THE ALT ALERTER (PF DOES THIS AS PROC WHEN AUTOPLT IS ENGAGED). CAPT WAS OFF THE RADIO TALKING TO THE PAX BRIEFLY ON PA SYS, SO I READ BACK THE CLRNC. AFTER READING BACK THE CLRNC OF 9000 AND THE CTLR ACKNOWLEDGED THIS, I RECALLED MOST CLRNCS ON PREVIOUS FLTS WERE TO CROSS VALRE AT 10000 (THIS IS DEPICTED ON THE EXTOL 1 ARR CHART INTO LGA, BUT OUR COMPANY FILED ROUTING DID NOT INCLUDE THIS STAR). ABOUT A MIN AFTER GIVEN THE ORIGINAL CLRNC TO 9000, I ASKED BOS TO RE- CONFIRM CROSS VALRE AT 9000. HE DID. BY THIS TIME CAPT WAS BACK ON THE RADIO AND ALSO HEARD VALRE AT 9000. XING OVER KINGSTON VOR (IGN) TRACKING VI57 SBOUND WE WERE APCHING 10000 WHEN TCASII GAVE US AN RA COMMAND 'CLB, CLB.' RA ON SCOPE WAS MINUS 500 AT 11 O'CLOCK LESS THAN 2 MI. VSI PRESENTATION DISPLAYED A FEW GREEN DOTS BTWN PLUS 1500 AND PLUS 2000 FPM CLB. THE REST OF THE DISPLAY SHOWED RED DOTS (TCASII WORKING AS DESIGNED!) I DISENGAGED AUTOPLT AND SMOOTHLY BUT FIRMLY RAISED NOSE TO ACHIEVE 2000 FPM CLB AND ADDED CLB PWR. CAPT NOTIFIED ATC OF RA AND THAT WE WERE CLBING DUE TO TCASII RA. ATC NOTIFIED US OF TFC AND CAPT VISUALLY PICKED UP THE ATR COMMUTER ACFT AT 11 O'CLOCK LOW, WHICH CAPT SAID LOOKED LIKE A ATR TURBO PROP. ZBW TOLD US THE TFC WAS SQUAWKING 1200 (VFR CODE) AT 9500 FT AND ATC WAS NOT WORKING HIM. I LATER CALLED ZBW ON THE TELEPHONE THAT SAME DAY AND SPOKE WITH THIS CTLR. HE INDICATED THAT THEY HAVE A WRITTEN LETTER FROM NY APCH CTL THAT INBOUND ACFT MUST BE AT 9000 FT, 40 NM NW OF DEER PARK VOR (DPK). I STATED THAT THE CURRENT EXTOL 1 ARR PLATE STATES 'EXPECT TO CROSS VALRE AT 10000.' THE CTLR SAID THEY (FAA) WILL CHANGE THIS TOO. HE EARLIER STATED THAT 'MANY COMMUTER ACFT ROUTINELY FLY VFR AT 9500 FT IN THIS AREA.' I SUGGESTED THAT IT WOULD BE SAFER TO KEEP INBOUND ACFT AT LEAST AT 10000 FT UNTIL S OF KINGSTON VOR BEFORE CLRING THEM TO DSND TO 9000. HE SAID HE WOULD PASS ALONG THE SUGGESTION TO HIS SUPVR. I FEEL WITHOUT THE ADVANCE WARNING GIVEN TO US BY TCASII, WE WOULD HAVE COME VERY CLOSE TO COLLIDING WITH THIS COMMUTER.

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.