Narrative:

Air carrier X departed btr for iah and was climbing swbound to 16000 ft. Light transport Y was nebound to land at btr descending from flight levels. Both aircraft were advised about the other (traffic calls), and I was just about to call traffic no factor when air carrier X starts telling me he has a TCASII alert and is going to level off. I told him traffic was no factor, but he leveled off anyway, disrupting other plans. I do not understand how pilots can just disregard ATC instructions, especially in a terminal environment.

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Original NASA ASRS Text

Title: ACR X TCASII RA FROM LTT NON ADHERENCE TO ATC CLRNC LEVEL OFF DURING CLB. TCASII RA DISRUPTIVE TO ATC.

Narrative: ACR X DEPARTED BTR FOR IAH AND WAS CLBING SWBOUND TO 16000 FT. LTT Y WAS NEBOUND TO LAND AT BTR DSNDING FROM FLT LEVELS. BOTH ACFT WERE ADVISED ABOUT THE OTHER (TFC CALLS), AND I WAS JUST ABOUT TO CALL TFC NO FACTOR WHEN ACR X STARTS TELLING ME HE HAS A TCASII ALERT AND IS GOING TO LEVEL OFF. I TOLD HIM TFC WAS NO FACTOR, BUT HE LEVELED OFF ANYWAY, DISRUPTING OTHER PLANS. I DO NOT UNDERSTAND HOW PLTS CAN JUST DISREGARD ATC INSTRUCTIONS, ESPECIALLY IN A TERMINAL ENVIRONMENT.

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.