Narrative:

We were approaching dtw at 6000 ft on the polar 1 arrival approximately 35 mi from dtw VOR when I noticed a target on the TCASII. The target showed 100 ft below our altitude, level, at our 1 O'clock position and 4 mi and appeared to be closing with us. I had the copilot query dtw approach control about the traffic while we both tried to acquire him visually. Before approach control could answer, we received an RA telling us to 'climb, climb,' which I responded to while the copilot advised approach that we were climbing in response to an RA. I climbed approximately 300 ft when the RA advised 'monitor vertical speed,' so I leveled at 6400 ft and got the 'clear of conflict,' I descended back to 6000 ft. I asked approach if he was aware of this traffic and he said he was being handled by flint, mi, approach and was VFR maintaining visual separation from us at 5800 ft. I said that I didn't feel 200 ft was adequate visual separation and he showed up as being at 5900 ft on my TCASII. He said 'well he's VFR.' we acquired the target visually and he was a dark blue biplane. We saw him as we began the RA maneuver. I was very glad to have had TCASII on board or we would have come very close to this aircraft, assuming we did not see it first. This 'maintain visual separation' shortcut is, in my opinion, a detriment to air safety. I was never told (as I am aware I am not required to be told) that I had an aircraft maintaining visual separation from me. I believe that both aircraft should be notified of a maintain visual separation clearance, or it should not be used. It is especially dangerous in the ase of a small (hard to see) light airplane plted by an inexperienced pilot told to maintain visual separation from an airliner (easy to see, hard to get away from). The small aircraft can easily see the airliner, but the difficulty comes with judging speed and closure rate -- most wkend private pilots don't have adequate training to safely do that. The problem comes when controllers 'sucker' pilots into a 'maintain visual separation' situation. The exchange goes something like this: controller: 'cessna 123, do you have the DC9 in sight 12 O'clock and 2 mi?' cessna: 'affirmative, we have him in sight.' controller: 'cessna 123, maintain visual separation from the DC9.' do you see the problem? Nobody has even talked to the DC9 and all of a sudden the onus is on the guy in the cessna who could be a brand new private pilot. Kind of a flawed system, don't you agree?

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Original NASA ASRS Text

Title: A DC9 PLT RECEIVED A TCASII RA AND NMAC FROM A VFR ACFT THAT WAS TO HAVE MAINTAINED SEPARATION NEAR DTW.

Narrative: WE WERE APCHING DTW AT 6000 FT ON THE POLAR 1 ARR APPROX 35 MI FROM DTW VOR WHEN I NOTICED A TARGET ON THE TCASII. THE TARGET SHOWED 100 FT BELOW OUR ALT, LEVEL, AT OUR 1 O'CLOCK POS AND 4 MI AND APPEARED TO BE CLOSING WITH US. I HAD THE COPLT QUERY DTW APCH CTL ABOUT THE TFC WHILE WE BOTH TRIED TO ACQUIRE HIM VISUALLY. BEFORE APCH CTL COULD ANSWER, WE RECEIVED AN RA TELLING US TO 'CLB, CLB,' WHICH I RESPONDED TO WHILE THE COPLT ADVISED APCH THAT WE WERE CLBING IN RESPONSE TO AN RA. I CLBED APPROX 300 FT WHEN THE RA ADVISED 'MONITOR VERT SPD,' SO I LEVELED AT 6400 FT AND GOT THE 'CLR OF CONFLICT,' I DSNDED BACK TO 6000 FT. I ASKED APCH IF HE WAS AWARE OF THIS TFC AND HE SAID HE WAS BEING HANDLED BY FLINT, MI, APCH AND WAS VFR MAINTAINING VISUAL SEPARATION FROM US AT 5800 FT. I SAID THAT I DIDN'T FEEL 200 FT WAS ADEQUATE VISUAL SEPARATION AND HE SHOWED UP AS BEING AT 5900 FT ON MY TCASII. HE SAID 'WELL HE'S VFR.' WE ACQUIRED THE TARGET VISUALLY AND HE WAS A DARK BLUE BIPLANE. WE SAW HIM AS WE BEGAN THE RA MANEUVER. I WAS VERY GLAD TO HAVE HAD TCASII ON BOARD OR WE WOULD HAVE COME VERY CLOSE TO THIS ACFT, ASSUMING WE DID NOT SEE IT FIRST. THIS 'MAINTAIN VISUAL SEPARATION' SHORTCUT IS, IN MY OPINION, A DETRIMENT TO AIR SAFETY. I WAS NEVER TOLD (AS I AM AWARE I AM NOT REQUIRED TO BE TOLD) THAT I HAD AN ACFT MAINTAINING VISUAL SEPARATION FROM ME. I BELIEVE THAT BOTH ACFT SHOULD BE NOTIFIED OF A MAINTAIN VISUAL SEPARATION CLRNC, OR IT SHOULD NOT BE USED. IT IS ESPECIALLY DANGEROUS IN THE ASE OF A SMALL (HARD TO SEE) LIGHT AIRPLANE PLTED BY AN INEXPERIENCED PLT TOLD TO MAINTAIN VISUAL SEPARATION FROM AN AIRLINER (EASY TO SEE, HARD TO GET AWAY FROM). THE SMALL ACFT CAN EASILY SEE THE AIRLINER, BUT THE DIFFICULTY COMES WITH JUDGING SPD AND CLOSURE RATE -- MOST WKEND PVT PLTS DON'T HAVE ADEQUATE TRAINING TO SAFELY DO THAT. THE PROB COMES WHEN CTLRS 'SUCKER' PLTS INTO A 'MAINTAIN VISUAL SEPARATION' SIT. THE EXCHANGE GOES SOMETHING LIKE THIS: CTLR: 'CESSNA 123, DO YOU HAVE THE DC9 IN SIGHT 12 O'CLOCK AND 2 MI?' CESSNA: 'AFFIRMATIVE, WE HAVE HIM IN SIGHT.' CTLR: 'CESSNA 123, MAINTAIN VISUAL SEPARATION FROM THE DC9.' DO YOU SEE THE PROB? NOBODY HAS EVEN TALKED TO THE DC9 AND ALL OF A SUDDEN THE ONUS IS ON THE GUY IN THE CESSNA WHO COULD BE A BRAND NEW PVT PLT. KIND OF A FLAWED SYS, DON'T YOU AGREE?

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.