Narrative:

Air carrier X B737 departed stl. I climbed him to 6000 ft on initial contact. An atx Y BA31 departed shortly after. I climbed him to 5000 ft. Low altitude apreq a satellite departure about 13 mi south of stl wbound. I was keeping jets at 6000 ft west of the propeller departure's aircraft also climbing propellers to 6000 ft for traffic (not my common practice). Air carrier X later called a previous departure in sight and level at 6000 ft. Instead of keeping him wide as planned I turned him south to join a departure route. Atx Y I later turned to a 160 degree heading and climbed to 6000 ft. Air carrier X said he had traffic off his nose and a mi. He asked what it was and what altitude. I advised a BA31 at 6000 ft. I soon climbed air carrier X to 15000 ft and turned atx X further on course. There were numerous VFR data tags on the scope making it difficult to discern targets. I use the small data blocks to help eliminate clutter. There are 4 sizes of data blocks available, but only 2 sizes can be used. The supervisor monitoring the area could not read the data because of size. Supplemental information from acn 265286: departure control issued a climb to 6000 ft MSL. I responded by giving call sign and 6000 ft traffic at 10 O'clock 3 mi in sight a dc-9. Departure then cleared us to maintain visual, turn left heading 180 degrees and intercept lindberg 2 departure, little rock transition. Once established on the departure, I noticed an atx Y 11 O'clock low and converging. I watched this aircraft climb to our altitude visually and with TCASII. I then queried departure and was told to standby. We slowed slightly so as not to overrun traffic. Departure asked what we wanted and I replied in question about our 12 O'clock 1 mi traffic. Departure's response was he's at 6000 ft. I replied yes so are we. Immediately the traffic turned left and was no longer a factor. A call to departure on the phone unveiled that he simply forgot that we were at 6000 ft MSL.

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Original NASA ASRS Text

Title: ACR X TCASII RA HAD LTSS FROM ATX Y. SYS ERROR.

Narrative: ACR X B737 DEPARTED STL. I CLBED HIM TO 6000 FT ON INITIAL CONTACT. AN ATX Y BA31 DEPARTED SHORTLY AFTER. I CLBED HIM TO 5000 FT. LOW ALT APREQ A SATELLITE DEP ABOUT 13 MI S OF STL WBOUND. I WAS KEEPING JETS AT 6000 FT W OF THE PROP DEP'S ACFT ALSO CLBING PROPS TO 6000 FT FOR TFC (NOT MY COMMON PRACTICE). ACR X LATER CALLED A PREVIOUS DEP IN SIGHT AND LEVEL AT 6000 FT. INSTEAD OF KEEPING HIM WIDE AS PLANNED I TURNED HIM S TO JOIN A DEP RTE. ATX Y I LATER TURNED TO A 160 DEG HDG AND CLBED TO 6000 FT. ACR X SAID HE HAD TFC OFF HIS NOSE AND A MI. HE ASKED WHAT IT WAS AND WHAT ALT. I ADVISED A BA31 AT 6000 FT. I SOON CLBED ACR X TO 15000 FT AND TURNED ATX X FURTHER ON COURSE. THERE WERE NUMEROUS VFR DATA TAGS ON THE SCOPE MAKING IT DIFFICULT TO DISCERN TARGETS. I USE THE SMALL DATA BLOCKS TO HELP ELIMINATE CLUTTER. THERE ARE 4 SIZES OF DATA BLOCKS AVAILABLE, BUT ONLY 2 SIZES CAN BE USED. THE SUPVR MONITORING THE AREA COULD NOT READ THE DATA BECAUSE OF SIZE. SUPPLEMENTAL INFORMATION FROM ACN 265286: DEP CTL ISSUED A CLB TO 6000 FT MSL. I RESPONDED BY GIVING CALL SIGN AND 6000 FT TFC AT 10 O'CLOCK 3 MI IN SIGHT A DC-9. DEP THEN CLRED US TO MAINTAIN VISUAL, TURN L HDG 180 DEGS AND INTERCEPT LINDBERG 2 DEP, LITTLE ROCK TRANSITION. ONCE ESTABLISHED ON THE DEP, I NOTICED AN ATX Y 11 O'CLOCK LOW AND CONVERGING. I WATCHED THIS ACFT CLB TO OUR ALT VISUALLY AND WITH TCASII. I THEN QUERIED DEP AND WAS TOLD TO STANDBY. WE SLOWED SLIGHTLY SO AS NOT TO OVERRUN TFC. DEP ASKED WHAT WE WANTED AND I REPLIED IN QUESTION ABOUT OUR 12 O'CLOCK 1 MI TFC. DEP'S RESPONSE WAS HE'S AT 6000 FT. I REPLIED YES SO ARE WE. IMMEDIATELY THE TFC TURNED L AND WAS NO LONGER A FACTOR. A CALL TO DEP ON THE PHONE UNVEILED THAT HE SIMPLY FORGOT THAT WE WERE AT 6000 FT MSL.

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.