ATCT LCL CTLR WORKING COMBINED POS IN THE TWR GAVE AN ACR DC10 TFC INFO ON A CESSNA TRAVERSING THE TWR'S AIRSPACE VFR INTO A CLOSE BY LAKE ARPT. THE CESSNA WAS ALSO GIVEN TFC ON THE DEPARTING DC10 AND SAID HE WAS IN SIGHT. ACFT PASSED IN CLOSE PROX AND THE DC10 RECEIVED AND RESPONDED TO A TCASII RA. THE DC10 SAID HE WOULD BE FILING A RPT ON THIS INCIDENT. NEITHER THE TWR CTLR NOR THE CESSNA PLT THOUGHT IT WAS THAT CLOSE.

Narrative

I WAS WORKING ANC LCL CTL; ANC GND CTL; AND LAKE HOOD TWR COMBINED AT ANC LCL CTL. ACR X WAS DEPARTING ANC RWY 32 IFR TO TAIPEI ON THE ANC 2 DEP SID. INBOUND FROM THE N WAS A CESSNA (SMA Y) TRANSITIONING TO CAMPBELL LAKE; WHICH IS LOCATED APPROX 3 MI SE OF ANC. TYPICALLY AN ACFT SUCH AS THIS WOULD BE ASSIGNED THE POST OFFICE ARR; A VFR ARR PROC THAT KEEPS INBOUND VFR ACFT E OF THE DEP COURSE FOR ACFT DEPARTING RWY 32. THE SMA Y WAS INITIALLY RADAR IDENTED BY ANC TRACON AND I CANNOT VERIFY WHETHER THIS ACFT WAS ISSUED THE POST OFFICE ARR OR NOT. MY INITIAL CONTACT WITH SMA Y WAS ONLY ONE AND ONE HALF MI N OF THE ARPT; WHICH IS UNUSUALLY LATE; AND I ADVISED SMA Y ABOUT THE HVY DC10 DEPARTING RWY 32 NWBOUND. SMA Y ADVISED THAT THEY HAD THE TFC IN SIGHT. OF NOTE WAS THE FACT THAT SMA Y WAS FLYING SBOUND UNUSUALLY CLOSE TO RWY 32; APPROX ONLY A HALF MI E OF THE RWY. AFTER ACR X DEPARTED I ADVISED THEM OF THE TFC; 'ACR X; TFC AHEAD AND R; SBOUND; A CESSNA; SLIGHTLY HIGHER.' AS THIS TFC CALL WAS BEING MADE THE D-BRITE INDICATED THAT SMA Y WAS AT 900 FT; AND ACR X WAS AT 600 FT; AND THE ACFT WERE SEPARATED BY LESS THAN 1 MI LATERALLY. BOTH ACFT WERE IN SIGHT BY ME AND THEIR POS VISUALLY DID NOT ALARM ME. AFTER THE ACFT PASSED; ACR X ADVISED THAT THEY HAD EXECUTED A TCASII RESOLUTION AFTER RECEIVING A TCASII WARNING; AND THAT THEIR TCASII HAD RPTED VIRTUALLY 0 LATERAL SEPARATION AND 300 FT OF VERT SEPARATION. THE CREW ADVISED THAT THEIR RA INDICATED THAT THEY SHOULD CLB ON COURSE. THE AIR CREW OF ACR X WAS VERY POLITE; BUT THEY ASKED ME SEVERAL QUESTIONS ABOUT THIS EVENT; AND THEY ADVISED THAT THEY WOULD BE FILING A RPT. THE PLT OF SMA Y SEEMED UNCONCERNED ABOUT THE INCIDENT. I SHOULD ADD THAT DUE TO THE CLOSE PROX OF SEVERAL ARPTS AND LNDG AREAS NEAR ANCHORAGE; THE ACFT THAT TYPICALLY FLY HERE ARE USED TO FLYING NEAR OTHER ACFT. ACR X ARE UNUSUAL IN ANCHORAGE; AND APPARENTLY THE SCENARIO I HAVE DESCRIBED IS EXTREMELY UNUSUAL FOR THEM.