Narrative:

Aircraft X, BA46, departed aspen on the powdr arrival to denver. Aircraft Y, C500, departed ase on the larks arrival to centennial airport, and aircraft Z, D328, on the powdr arrival landing denver. All tied and in conflict regarding their dscnts to make the appropriate crossing restr altitude. All aircraft were already on frequency when I came in to get another controller out for a break. The previous controller cleared both aircraft X and aircraft Y direct to their respective gates. Aircraft X had a 40 KT overtake on aircraft Y with approximately 9 NM lateral separation. No action had been taken to get these aircraft started down when the position relief briefing began. Before I was given the briefing I was concerned with how each of these aircraft were going to get down. Sector is very small and the aircraft at the highest altitude had to cross at the lowest altitude. Aircraft Z had to cross powdr at 17000 ft. Aircraft X had to cross powdr at FL190. Aircraft Y had to cross larks at 17000 ft. Aircraft Y was turned to the right to get him away from aircraft X and start his descent. Aircraft Z was also turned to the right to get him away from aircraft X and was stepped down in altitude reference to aircraft Y's descent. Time based metering was in effect and I was concerned with the metering times because the previous controller cleared 2 aircraft direct which would make them early for their metering time, and I was concerned that turning aircraft Z out for traffic was now going to move him late. In my haste to get aircraft Z back direct to the powdr gate to prevent him from being late for his ctas time, I issued the crossing restr to aircraft Z before he was laterally separated from aircraft Y. Conflict alert activated when aircraft Z left FL180 with aircraft Y level at 17000 ft. I told aircraft Z to maintain FL180 and he called his traffic in sight. I did not issue any other means of separation. Aircraft Z was already in a hard turn back to powdr and had the traffic in sight. Another factor in this error is that the controller I relieved uses settings completely different from mine, ie, multi-fr function, clock placement, rcro placement, ctas list placement -- all of which do not repos when you sign in with your initials. This is a major distraction when you first situation down and you are trying to get your scope set up. I was using the track ball to select each aircraft to find out their types and speeds, but it didn't show up on the scope where I expected it to. This is a major factor. All settings and positioning must move to where you like them when you first sign in on the sector. It would prevent a major distraction when you first situation down.

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Original NASA ASRS Text

Title: SEPARATION LOST BY ZDV CTLRS BTWN 2 ARRS INTO DEN DURING POS RELIEF.

Narrative: ACFT X, BA46, DEPARTED ASPEN ON THE POWDR ARR TO DENVER. ACFT Y, C500, DEPARTED ASE ON THE LARKS ARR TO CENTENNIAL ARPT, AND ACFT Z, D328, ON THE POWDR ARR LNDG DENVER. ALL TIED AND IN CONFLICT REGARDING THEIR DSCNTS TO MAKE THE APPROPRIATE XING RESTR ALT. ALL ACFT WERE ALREADY ON FREQ WHEN I CAME IN TO GET ANOTHER CTLR OUT FOR A BREAK. THE PREVIOUS CTLR CLRED BOTH ACFT X AND ACFT Y DIRECT TO THEIR RESPECTIVE GATES. ACFT X HAD A 40 KT OVERTAKE ON ACFT Y WITH APPROX 9 NM LATERAL SEPARATION. NO ACTION HAD BEEN TAKEN TO GET THESE ACFT STARTED DOWN WHEN THE POS RELIEF BRIEFING BEGAN. BEFORE I WAS GIVEN THE BRIEFING I WAS CONCERNED WITH HOW EACH OF THESE ACFT WERE GOING TO GET DOWN. SECTOR IS VERY SMALL AND THE ACFT AT THE HIGHEST ALT HAD TO CROSS AT THE LOWEST ALT. ACFT Z HAD TO CROSS POWDR AT 17000 FT. ACFT X HAD TO CROSS POWDR AT FL190. ACFT Y HAD TO CROSS LARKS AT 17000 FT. ACFT Y WAS TURNED TO THE R TO GET HIM AWAY FROM ACFT X AND START HIS DSCNT. ACFT Z WAS ALSO TURNED TO THE R TO GET HIM AWAY FROM ACFT X AND WAS STEPPED DOWN IN ALT REF TO ACFT Y'S DSCNT. TIME BASED METERING WAS IN EFFECT AND I WAS CONCERNED WITH THE METERING TIMES BECAUSE THE PREVIOUS CTLR CLRED 2 ACFT DIRECT WHICH WOULD MAKE THEM EARLY FOR THEIR METERING TIME, AND I WAS CONCERNED THAT TURNING ACFT Z OUT FOR TFC WAS NOW GOING TO MOVE HIM LATE. IN MY HASTE TO GET ACFT Z BACK DIRECT TO THE POWDR GATE TO PREVENT HIM FROM BEING LATE FOR HIS CTAS TIME, I ISSUED THE XING RESTR TO ACFT Z BEFORE HE WAS LATERALLY SEPARATED FROM ACFT Y. CONFLICT ALERT ACTIVATED WHEN ACFT Z LEFT FL180 WITH ACFT Y LEVEL AT 17000 FT. I TOLD ACFT Z TO MAINTAIN FL180 AND HE CALLED HIS TFC IN SIGHT. I DID NOT ISSUE ANY OTHER MEANS OF SEPARATION. ACFT Z WAS ALREADY IN A HARD TURN BACK TO POWDR AND HAD THE TFC IN SIGHT. ANOTHER FACTOR IN THIS ERROR IS THAT THE CTLR I RELIEVED USES SETTINGS COMPLETELY DIFFERENT FROM MINE, IE, MULTI-FR FUNCTION, CLOCK PLACEMENT, RCRO PLACEMENT, CTAS LIST PLACEMENT -- ALL OF WHICH DO NOT REPOS WHEN YOU SIGN IN WITH YOUR INITIALS. THIS IS A MAJOR DISTR WHEN YOU FIRST SIT DOWN AND YOU ARE TRYING TO GET YOUR SCOPE SET UP. I WAS USING THE TRACK BALL TO SELECT EACH ACFT TO FIND OUT THEIR TYPES AND SPDS, BUT IT DIDN'T SHOW UP ON THE SCOPE WHERE I EXPECTED IT TO. THIS IS A MAJOR FACTOR. ALL SETTINGS AND POSITIONING MUST MOVE TO WHERE YOU LIKE THEM WHEN YOU FIRST SIGN IN ON THE SECTOR. IT WOULD PREVENT A MAJOR DISTR WHEN YOU FIRST SIT DOWN.

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.