Narrative:

Started my shift at XA55. Winds out of the nnw. Aircraft would not depart runway 25; only wanted runway 1. Runway 1 restr to less than 6000 ft due to construction. There was a good deal of confusion as to what runway confign to be on. No set standard for the situation at hand. I was told that all air carrier's were to land on runway 25L or runway 25R due to tower needing runway 1L for departures. We were now on runway confign 3; runway 1 and runway 25. On this confign; normally arrs from the northeast; the northwest; and southwest; land on runway 1L. Only the southeast flow lands on runway 25. Lots of nonstandard operations going on. I was working the granite (gnt) approach sector; northwest and northeast arrs. These almost always land on runway 1L. Today; I was taking them all to runway 25. I had air carrier X from the northeast. A different sector to runway 25L (I think canyon; cyn) had C441 on the localizer to runway 25L tracking west; landing at vgt airport (approximately 10 mi northwest of las). This aircraft was pointed out to me at 8000 ft would be descending to 6000 ft so not to conflict with my aircraft descending to 8000 ft for the downwind. I descended air carrier X from 9000 ft to 8000 ft believing C441 was already below 7000 ft. Data on his altitude was time sharing with his destination. I saw this instead of his altitude. I assumed he was lower because they always are -- not this time. I issued a traffic alert to air carrier X; climbed him; and turned him. I think that aircraft should not overfly the airport at altitudes the downwind are flown at.

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Original NASA ASRS Text

Title: L30 CTLR EXPERIENCED OPERROR AT APPROX 8000 FT WHEN FAILING TO OBSERVE ALT OF ACFT LNDG AT VGT.

Narrative: STARTED MY SHIFT AT XA55. WINDS OUT OF THE NNW. ACFT WOULD NOT DEPART RWY 25; ONLY WANTED RWY 1. RWY 1 RESTR TO LESS THAN 6000 FT DUE TO CONSTRUCTION. THERE WAS A GOOD DEAL OF CONFUSION AS TO WHAT RWY CONFIGN TO BE ON. NO SET STANDARD FOR THE SITUATION AT HAND. I WAS TOLD THAT ALL ACR'S WERE TO LAND ON RWY 25L OR RWY 25R DUE TO TWR NEEDING RWY 1L FOR DEPS. WE WERE NOW ON RWY CONFIGN 3; RWY 1 AND RWY 25. ON THIS CONFIGN; NORMALLY ARRS FROM THE NE; THE NW; AND SW; LAND ON RWY 1L. ONLY THE SE FLOW LANDS ON RWY 25. LOTS OF NONSTANDARD OPS GOING ON. I WAS WORKING THE GRANITE (GNT) APCH SECTOR; NW AND NE ARRS. THESE ALMOST ALWAYS LAND ON RWY 1L. TODAY; I WAS TAKING THEM ALL TO RWY 25. I HAD ACR X FROM THE NE. A DIFFERENT SECTOR TO RWY 25L (I THINK CANYON; CYN) HAD C441 ON THE LOC TO RWY 25L TRACKING W; LNDG AT VGT ARPT (APPROX 10 MI NW OF LAS). THIS ACFT WAS POINTED OUT TO ME AT 8000 FT WOULD BE DSNDING TO 6000 FT SO NOT TO CONFLICT WITH MY ACFT DSNDING TO 8000 FT FOR THE DOWNWIND. I DSNDED ACR X FROM 9000 FT TO 8000 FT BELIEVING C441 WAS ALREADY BELOW 7000 FT. DATA ON HIS ALT WAS TIME SHARING WITH HIS DEST. I SAW THIS INSTEAD OF HIS ALT. I ASSUMED HE WAS LOWER BECAUSE THEY ALWAYS ARE -- NOT THIS TIME. I ISSUED A TFC ALERT TO ACR X; CLBED HIM; AND TURNED HIM. I THINK THAT ACFT SHOULD NOT OVERFLY THE ARPT AT ALTS THE DOWNWIND ARE FLOWN AT.

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.