Narrative:

We were descending from 8000 to 6000' when abe approach called 2 targets. We called tally ho on both. We were told to 'keep the second target in sight, he will be climbing through your altitude.' this target was an small transport turbo propeller who was working abe approach on another frequency. He called us in sight (I talked to the other captain on the phone the next day) and he was cleared to climb from 4000 to 8000'. At the same time he was cleared to resume normal navigation (the captain told me the next day that this was interpreted as a clearance to go direct lrp VOR. Then we were told to descend to 4000' and to maintain visibility sep. My copilot was the PF. Both he and I were uncomfortable with this situation from the moment that we were told to 'keep him in sight, he'll be climbing through your altitude,' but we did not say anything to the controller. As in many things concerning high density traffic, we've come to accept too many uncomfortable situations in the interests of getting along with ATC. When we were told to descend to 4000' we decided to level off at 6000' to evaluate the geometry of this situation. It appeared that it would be close, but not as close as it turned out to be. The wild card was that the other crew started flying by reference to the gauges, started a 2000 FPM climb and turned 20 to 30 degrees into us as they turned to go direct to lrp VOR. I was looking right at the target the entire time. I told the copilot that he was 'sliding behind us.' he passed my aircraft at my 8 O'clock position, just slightly below me. The rapidity of the changing geometry (2000 FPM climb, 20-30 degree heading change) at night made it very difficult to maintain visibility sep. 1) the controller put us in a dangerous position and assumed that we were willing and able to maintain visibility sep. 2) the other aircraft did not keep us in sight after they called us in sight and initiated a maximum climb and turn into us. 3) we did not express our misgivings to ATC. Lesson: be aggressive, don't worry so much about ATC relations.

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Original NASA ASRS Text

Title: 2 ACR ACFT, 1 CLIMBING, 1 DESCENDING, EACH GIVEN THE OTHER AS TRAFFIC FOR SEPARATION, HAD NMAC.

Narrative: WE WERE DSNDING FROM 8000 TO 6000' WHEN ABE APCH CALLED 2 TARGETS. WE CALLED TALLY HO ON BOTH. WE WERE TOLD TO 'KEEP THE SECOND TARGET IN SIGHT, HE WILL BE CLBING THROUGH YOUR ALT.' THIS TARGET WAS AN SMT TURBO PROP WHO WAS WORKING ABE APCH ON ANOTHER FREQ. HE CALLED US IN SIGHT (I TALKED TO THE OTHER CAPT ON THE PHONE THE NEXT DAY) AND HE WAS CLRED TO CLB FROM 4000 TO 8000'. AT THE SAME TIME HE WAS CLRED TO RESUME NORMAL NAV (THE CAPT TOLD ME THE NEXT DAY THAT THIS WAS INTERPRETED AS A CLRNC TO GO DIRECT LRP VOR. THEN WE WERE TOLD TO DSND TO 4000' AND TO MAINTAIN VIS SEP. MY COPLT WAS THE PF. BOTH HE AND I WERE UNCOMFORTABLE WITH THIS SITUATION FROM THE MOMENT THAT WE WERE TOLD TO 'KEEP HIM IN SIGHT, HE'LL BE CLBING THROUGH YOUR ALT,' BUT WE DID NOT SAY ANYTHING TO THE CTLR. AS IN MANY THINGS CONCERNING HIGH DENSITY TFC, WE'VE COME TO ACCEPT TOO MANY UNCOMFORTABLE SITUATIONS IN THE INTERESTS OF GETTING ALONG WITH ATC. WHEN WE WERE TOLD TO DSND TO 4000' WE DECIDED TO LEVEL OFF AT 6000' TO EVALUATE THE GEOMETRY OF THIS SITUATION. IT APPEARED THAT IT WOULD BE CLOSE, BUT NOT AS CLOSE AS IT TURNED OUT TO BE. THE WILD CARD WAS THAT THE OTHER CREW STARTED FLYING BY REF TO THE GAUGES, STARTED A 2000 FPM CLB AND TURNED 20 TO 30 DEGS INTO US AS THEY TURNED TO GO DIRECT TO LRP VOR. I WAS LOOKING RIGHT AT THE TARGET THE ENTIRE TIME. I TOLD THE COPLT THAT HE WAS 'SLIDING BEHIND US.' HE PASSED MY ACFT AT MY 8 O'CLOCK POS, JUST SLIGHTLY BELOW ME. THE RAPIDITY OF THE CHANGING GEOMETRY (2000 FPM CLB, 20-30 DEG HDG CHANGE) AT NIGHT MADE IT VERY DIFFICULT TO MAINTAIN VIS SEP. 1) THE CTLR PUT US IN A DANGEROUS POS AND ASSUMED THAT WE WERE WILLING AND ABLE TO MAINTAIN VIS SEP. 2) THE OTHER ACFT DID NOT KEEP US IN SIGHT AFTER THEY CALLED US IN SIGHT AND INITIATED A MAX CLB AND TURN INTO US. 3) WE DID NOT EXPRESS OUR MISGIVINGS TO ATC. LESSON: BE AGGRESSIVE, DON'T WORRY SO MUCH ABOUT ATC RELATIONS.

Data retrieved from NASA's ASRS site as of August 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.