Narrative:

Shortly after takeoff from bdl en route to pit, we were handed off to ZBW. Clearance was direct to center VOR. At 11000 ft, we were advised of turboprop traffic at '12000 ft, 1-2 O'clock, approximately 8 mi.' we acquired the traffic visually and via TCASII at 2 O'clock and advised ATC. At this point, ZBW issued these instructions: 'maintain visual separation with that traffic, climb and maintain 17000 ft, no delay through 13000 ft.' after acknowledging this clearance, the first officer and I determined by visual references and the TCASII that we could initiate a quick climb and maintain separation, although the traffic was tracking straight down the 2 O'clock line of the TCASII. After initiating the climb, the TCASII issued a TA, whereupon the first officer, flying the plane, increased the climb rate. The TA was followed quickly by an insistent RA ('descend! Descend now!). Since we were already committed to a high rate of climb at approximately 20 degree deck angle and 5000 FPM rate of climb and trading airspeed for altitude from the initial 310 KTS, we continued the climb and made a clearing turn of about 30 degrees to the left of our route clearance. From the TCASII we concluded that we passed 12000 ft, the target's altitude, at approximately 3.5 NM range, and cleared 13000 ft at about 3.0 NM range. Airspeed at the conclusion of the evasive maneuver was 230 KTS. The other traffic made no apparent change in flight path or altitude. The traffic passed almost directly below us. 1) ZBW was remiss in issuing these climb instructions -- this is a technique allowed for approach/departure control but not for ARTCC. 2) we were mistaken in accepting this clearance, and then in initiating the climb which resulted in reduced separation. 3) it is always dangerous to disregard a TCASII RA, but under visual conditions we were more comfortable doing this than attempting to transition from a 5000 FPM climb to a 3000 FPM descent. The big problem potential is that the other traffic would have been issued a 'climb' RA which would have further reduced separation. Presumably, this is precisely what would have happened if the other traffic had been TCASII-equipped without a visual contact on us. Supplemental information from acn 298009: we were level at 11000 ft nwbound about 10 NM southeast of center, awaiting climb clearance from center. Center calls out traffic at 2 O'clock and level at 12000 ft wbound, I don't recall the distance. We advised center we had the traffic in sight. Center hesitates for a moment and says to climb to 17000 ft and no delay through 13000 ft. We check the traffic, and it's 6 mi now. We both felt comfortable that if we expedited the climb, it should be no problem. I immediately engaged cws on the autoplt and started a 5000-6000 FPM climb. Immediately after I initiated the climb, TCASII displayed a TA alert. Soon after, TCASII displayed an RA, commanding a descent. Since I had the traffic in sight, I kept the aircraft climbing through 12500 ft. While turning left (wbound) to get more spacing. I saw the commuter turboprop pass beneath us at about 13000 ft. This situation was one of those live and learn and too close for comfort. I'm never going to accept a clearance like that again. I'm just going to advise that we'll wait for traffic to clear whether we have the traffic in sight or not. Callback conversation with reporter revealed the following information: both rptrs informed the ctrs can now use visual separation below FL180. This was effective in feb/xx/95.

Google
 

Original NASA ASRS Text

Title: ACR X CLB THROUGH OCCUPIED ALT VISUAL SEPARATION BY CTR RECEIVED TCASII RA WITH ACFT Y.

Narrative: SHORTLY AFTER TKOF FROM BDL ENRTE TO PIT, WE WERE HANDED OFF TO ZBW. CLRNC WAS DIRECT TO CTR VOR. AT 11000 FT, WE WERE ADVISED OF TURBOPROP TFC AT '12000 FT, 1-2 O'CLOCK, APPROX 8 MI.' WE ACQUIRED THE TFC VISUALLY AND VIA TCASII AT 2 O'CLOCK AND ADVISED ATC. AT THIS POINT, ZBW ISSUED THESE INSTRUCTIONS: 'MAINTAIN VISUAL SEPARATION WITH THAT TFC, CLB AND MAINTAIN 17000 FT, NO DELAY THROUGH 13000 FT.' AFTER ACKNOWLEDGING THIS CLRNC, THE FO AND I DETERMINED BY VISUAL REFS AND THE TCASII THAT WE COULD INITIATE A QUICK CLB AND MAINTAIN SEPARATION, ALTHOUGH THE TFC WAS TRACKING STRAIGHT DOWN THE 2 O'CLOCK LINE OF THE TCASII. AFTER INITIATING THE CLB, THE TCASII ISSUED A TA, WHEREUPON THE FO, FLYING THE PLANE, INCREASED THE CLB RATE. THE TA WAS FOLLOWED QUICKLY BY AN INSISTENT RA ('DSND! DSND NOW!). SINCE WE WERE ALREADY COMMITTED TO A HIGH RATE OF CLB AT APPROX 20 DEG DECK ANGLE AND 5000 FPM RATE OF CLB AND TRADING AIRSPD FOR ALT FROM THE INITIAL 310 KTS, WE CONTINUED THE CLB AND MADE A CLRING TURN OF ABOUT 30 DEGS TO THE L OF OUR RTE CLRNC. FROM THE TCASII WE CONCLUDED THAT WE PASSED 12000 FT, THE TARGET'S ALT, AT APPROX 3.5 NM RANGE, AND CLRED 13000 FT AT ABOUT 3.0 NM RANGE. AIRSPD AT THE CONCLUSION OF THE EVASIVE MANEUVER WAS 230 KTS. THE OTHER TFC MADE NO APPARENT CHANGE IN FLT PATH OR ALT. THE TFC PASSED ALMOST DIRECTLY BELOW US. 1) ZBW WAS REMISS IN ISSUING THESE CLB INSTRUCTIONS -- THIS IS A TECHNIQUE ALLOWED FOR APCH/DEP CTL BUT NOT FOR ARTCC. 2) WE WERE MISTAKEN IN ACCEPTING THIS CLRNC, AND THEN IN INITIATING THE CLB WHICH RESULTED IN REDUCED SEPARATION. 3) IT IS ALWAYS DANGEROUS TO DISREGARD A TCASII RA, BUT UNDER VISUAL CONDITIONS WE WERE MORE COMFORTABLE DOING THIS THAN ATTEMPTING TO TRANSITION FROM A 5000 FPM CLB TO A 3000 FPM DSCNT. THE BIG PROB POTENTIAL IS THAT THE OTHER TFC WOULD HAVE BEEN ISSUED A 'CLB' RA WHICH WOULD HAVE FURTHER REDUCED SEPARATION. PRESUMABLY, THIS IS PRECISELY WHAT WOULD HAVE HAPPENED IF THE OTHER TFC HAD BEEN TCASII-EQUIPPED WITHOUT A VISUAL CONTACT ON US. SUPPLEMENTAL INFO FROM ACN 298009: WE WERE LEVEL AT 11000 FT NWBOUND ABOUT 10 NM SE OF CTR, AWAITING CLB CLRNC FROM CTR. CTR CALLS OUT TFC AT 2 O'CLOCK AND LEVEL AT 12000 FT WBOUND, I DON'T RECALL THE DISTANCE. WE ADVISED CTR WE HAD THE TFC IN SIGHT. CTR HESITATES FOR A MOMENT AND SAYS TO CLB TO 17000 FT AND NO DELAY THROUGH 13000 FT. WE CHK THE TFC, AND IT'S 6 MI NOW. WE BOTH FELT COMFORTABLE THAT IF WE EXPEDITED THE CLB, IT SHOULD BE NO PROB. I IMMEDIATELY ENGAGED CWS ON THE AUTOPLT AND STARTED A 5000-6000 FPM CLB. IMMEDIATELY AFTER I INITIATED THE CLB, TCASII DISPLAYED A TA ALERT. SOON AFTER, TCASII DISPLAYED AN RA, COMMANDING A DSCNT. SINCE I HAD THE TFC IN SIGHT, I KEPT THE ACFT CLBING THROUGH 12500 FT. WHILE TURNING L (WBOUND) TO GET MORE SPACING. I SAW THE COMMUTER TURBOPROP PASS BENEATH US AT ABOUT 13000 FT. THIS SIT WAS ONE OF THOSE LIVE AND LEARN AND TOO CLOSE FOR COMFORT. I'M NEVER GOING TO ACCEPT A CLRNC LIKE THAT AGAIN. I'M JUST GOING TO ADVISE THAT WE'LL WAIT FOR TFC TO CLR WHETHER WE HAVE THE TFC IN SIGHT OR NOT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: BOTH RPTRS INFORMED THE CTRS CAN NOW USE VISUAL SEPARATION BELOW FL180. THIS WAS EFFECTIVE IN FEB/XX/95.

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.