Narrative:

The aircraft under my control was a commuter light transport X and the aircraft being controled by another controller was cga Y, an small transport. The airspace at portland TRACON (P80), or, was split into 2 sectors, newberg ('U') and departure ('D'). I was working the 'U' sector. The split consisted of basically splitting all of P80 airspace in half from east to west, with the exception of a portion of the airspace to the west of the airport which would normally be owned by the portland final ('F') controller would now be owned by the 'D' sector. The normal procedure is for the 2 controllers ('D' and 'U') in this confign to share the 'F' airspace. I was working the 'U' position and I cleared light transport X for a visual approach to follow cga Y. At the time the clearance was issued he did not see cga Y, but I anticipated that he would. I believe the visibility was clear. The problems arose when the 'D' controller reminded me that my aircraft was going to eat up the space between the 2 aircraft because his cga had slowed down considerably. I believed that the light transport X had seen the cga by now and just hadn't slowed to follow. But that was not the case, after giving an update on the traffic, light transport X was to follow, he replied that he was looking. I slowed the light transport X down to match speeds with the cga. But the scenario grew worse even though the light transport X did get the cga in sight because the cga overshot his final and had to make a wide turn back toward the airport. I finally turned the light transport X out and vectored him back for another approach. 2 controllers working aircraft on separate frequencys through the same airspace and always trying to second guess what the other guy is doing. For if I had been working both aircraft, then this scenario would not have happened, because I would have ensured that the leading aircraft (the cga) was given a speed to maintain and the following aircraft (light transport X) was slowed to match up further out. For at the time, the clearance was issued to light transport X the speeds were matched. Have 1 controller or the other own the airspace and work the airplanes within that airspace. If this becomes too busy, then the final position should be opened.

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Original NASA ASRS Text

Title: CTLR RUNS COMMUTER ACFT TOO CLOSE TO ANOTHER ACFT BEING WORKED BY AN ADJACENT CTLR.

Narrative: THE ACFT UNDER MY CTL WAS A COMMUTER LTT X AND THE ACFT BEING CTLED BY ANOTHER CTLR WAS CGA Y, AN SMT. THE AIRSPACE AT PORTLAND TRACON (P80), OR, WAS SPLIT INTO 2 SECTORS, NEWBERG ('U') AND DEP ('D'). I WAS WORKING THE 'U' SECTOR. THE SPLIT CONSISTED OF BASICALLY SPLITTING ALL OF P80 AIRSPACE IN HALF FROM E TO W, WITH THE EXCEPTION OF A PORTION OF THE AIRSPACE TO THE W OF THE ARPT WHICH WOULD NORMALLY BE OWNED BY THE PORTLAND FINAL ('F') CTLR WOULD NOW BE OWNED BY THE 'D' SECTOR. THE NORMAL PROC IS FOR THE 2 CTLRS ('D' AND 'U') IN THIS CONFIGN TO SHARE THE 'F' AIRSPACE. I WAS WORKING THE 'U' POS AND I CLRED LTT X FOR A VISUAL APCH TO FOLLOW CGA Y. AT THE TIME THE CLRNC WAS ISSUED HE DID NOT SEE CGA Y, BUT I ANTICIPATED THAT HE WOULD. I BELIEVE THE VISIBILITY WAS CLR. THE PROBLEMS AROSE WHEN THE 'D' CTLR REMINDED ME THAT MY ACFT WAS GOING TO EAT UP THE SPACE BTWN THE 2 ACFT BECAUSE HIS CGA HAD SLOWED DOWN CONSIDERABLY. I BELIEVED THAT THE LTT X HAD SEEN THE CGA BY NOW AND JUST HADN'T SLOWED TO FOLLOW. BUT THAT WAS NOT THE CASE, AFTER GIVING AN UPDATE ON THE TFC, LTT X WAS TO FOLLOW, HE REPLIED THAT HE WAS LOOKING. I SLOWED THE LTT X DOWN TO MATCH SPDS WITH THE CGA. BUT THE SCENARIO GREW WORSE EVEN THOUGH THE LTT X DID GET THE CGA IN SIGHT BECAUSE THE CGA OVERSHOT HIS FINAL AND HAD TO MAKE A WIDE TURN BACK TOWARD THE ARPT. I FINALLY TURNED THE LTT X OUT AND VECTORED HIM BACK FOR ANOTHER APCH. 2 CTLRS WORKING ACFT ON SEPARATE FREQS THROUGH THE SAME AIRSPACE AND ALWAYS TRYING TO SECOND GUESS WHAT THE OTHER GUY IS DOING. FOR IF I HAD BEEN WORKING BOTH ACFT, THEN THIS SCENARIO WOULD NOT HAVE HAPPENED, BECAUSE I WOULD HAVE ENSURED THAT THE LEADING ACFT (THE CGA) WAS GIVEN A SPD TO MAINTAIN AND THE FOLLOWING ACFT (LTT X) WAS SLOWED TO MATCH UP FURTHER OUT. FOR AT THE TIME, THE CLRNC WAS ISSUED TO LTT X THE SPDS WERE MATCHED. HAVE 1 CTLR OR THE OTHER OWN THE AIRSPACE AND WORK THE AIRPLANES WITHIN THAT AIRSPACE. IF THIS BECOMES TOO BUSY, THEN THE FINAL POS SHOULD BE OPENED.

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.