Narrative:

During this period of day there are a mix of incompatible types of aircraft. Being that there is only 1 downwind at salt lake because of terrain proximity; we are forced to run 'stacks' in the downwind. We do have a procedure called 'over the tops to runway 32' which takes slower aircraft from the downwind and vectors them over and east of the airport in attempt to alleviate complexity for the final controller. During this situation the procedure was not used because of airport construction resulting in the closure of runway 32. This in itself creates a complex session for the final controller -- which today; workload was increased dramatically. I was not afforded a handoff or assist. I received radar and radio communications with aircraft X; a C208 in the downwind; heading 160 degrees at 11000 ft. In trail; roughly 3 mi of aircraft X; was air carrier Y (a CRJ2). In these circumstances we typically try to get the faster aircraft to pass to get in front. We either use visual separation to descend in front; or wait until standard separation is achieved. Air carrier Y checked on frequency doing 190 KTS. At this point my thought was to get him to speed up to achieve the pass faster; so I increased his speed to 210 KTS; with the intent to re-emphasize the 12000 ft altitude. I inadvertently said 11000 ft. This error was due to being spread thin at the time of the incident. I was on the final position for 1 hour 24 mins and I felt mentally tired. I was not relieved from position until approximately 30 mins after the incident.

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Original NASA ASRS Text

Title: S56 CTLR EXPERIENCED OPERROR AT 12000 FT WHEN ISSUING CONFLICTING ALT DURING DOWNWIND PASSING MANEUVER ATTEMPT.

Narrative: DURING THIS PERIOD OF DAY THERE ARE A MIX OF INCOMPATIBLE TYPES OF ACFT. BEING THAT THERE IS ONLY 1 DOWNWIND AT SALT LAKE BECAUSE OF TERRAIN PROX; WE ARE FORCED TO RUN 'STACKS' IN THE DOWNWIND. WE DO HAVE A PROC CALLED 'OVER THE TOPS TO RWY 32' WHICH TAKES SLOWER ACFT FROM THE DOWNWIND AND VECTORS THEM OVER AND E OF THE ARPT IN ATTEMPT TO ALLEVIATE COMPLEXITY FOR THE FINAL CTLR. DURING THIS SITUATION THE PROC WAS NOT USED BECAUSE OF ARPT CONSTRUCTION RESULTING IN THE CLOSURE OF RWY 32. THIS IN ITSELF CREATES A COMPLEX SESSION FOR THE FINAL CTLR -- WHICH TODAY; WORKLOAD WAS INCREASED DRAMATICALLY. I WAS NOT AFFORDED A HDOF OR ASSIST. I RECEIVED RADAR AND RADIO COMS WITH ACFT X; A C208 IN THE DOWNWIND; HDG 160 DEGS AT 11000 FT. IN TRAIL; ROUGHLY 3 MI OF ACFT X; WAS ACR Y (A CRJ2). IN THESE CIRCUMSTANCES WE TYPICALLY TRY TO GET THE FASTER ACFT TO PASS TO GET IN FRONT. WE EITHER USE VISUAL SEPARATION TO DSND IN FRONT; OR WAIT UNTIL STANDARD SEPARATION IS ACHIEVED. ACR Y CHKED ON FREQ DOING 190 KTS. AT THIS POINT MY THOUGHT WAS TO GET HIM TO SPD UP TO ACHIEVE THE PASS FASTER; SO I INCREASED HIS SPD TO 210 KTS; WITH THE INTENT TO RE-EMPHASIZE THE 12000 FT ALT. I INADVERTENTLY SAID 11000 FT. THIS ERROR WAS DUE TO BEING SPREAD THIN AT THE TIME OF THE INCIDENT. I WAS ON THE FINAL POS FOR 1 HR 24 MINS AND I FELT MENTALLY TIRED. I WAS NOT RELIEVED FROM POS UNTIL APPROX 30 MINS AFTER THE INCIDENT.

Data retrieved from NASA's ASRS site as of January 2009 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.