Narrative:

Medium large transport X slc-lax was cleared divet profile descent by sector 19. Sector 20 received handoff and issued amended altitude to 11000' and issued traffic, small transport Y at 10500'. I had received a pointout from ont approach on the twin. Medium large transport X advised no contact. Observed mode C and pilot report 11000'. Next update issued traffic again. Pilot advised TCAS alert and had already climbed to 11500' and was descending back. VFR 10500' never climbed, stayed in cruise. Pilot called and advised company policy was to do what TCAS indicated. Don't misunderstand--I feel TCAS is a great tool, but in this case ATC was working both aircraft and to climb I feel is wrong. Is this something that as a controller I must build into my sep standards or not? Please advise. Callback conversation with reporter revealed the following: discussed TCAS problems. Reporter states this is a growing problem and feels it is unsafe, especially when traffic issued as known and is at legal sep minima. Feels that FAA must get some rules and regulations out quickly so controllers and flight crews know where they stand. Reporter feels that problem even worse in positive control area where traffic is called at legal minima sep and aircraft still leave altitude due to TCAS ii alerts, mostly based on aircraft climb rates and aircraft will and usually level off at proper altitude below traffic. Analyst could only state that ASRS is receiving more and more reports on aircraft deviating from assigned altitude due to overreaction by flight crews or misaligned equipment. FAA is studying problem, but so far no solution to controller's dilemma.

Related reports:

Google
 

Original NASA ASRS Text

Title: CTLR GAVE ACR MLG TRAFFIC, VFR SMT AT PROPER VFR ALT. MLG FOLLOWED TCAS II ALERT AND CLIMBED OUT OF ASSIGNED ALT WITHOUT CLRNC.

Narrative: MLG X SLC-LAX WAS CLRED DIVET PROFILE DSNT BY SECTOR 19. SECTOR 20 RECEIVED HDOF AND ISSUED AMENDED ALT TO 11000' AND ISSUED TFC, SMT Y AT 10500'. I HAD RECEIVED A POINTOUT FROM ONT APCH ON THE TWIN. MLG X ADVISED NO CONTACT. OBSERVED MODE C AND PLT RPT 11000'. NEXT UPDATE ISSUED TFC AGAIN. PLT ADVISED TCAS ALERT AND HAD ALREADY CLBED TO 11500' AND WAS DSNDING BACK. VFR 10500' NEVER CLBED, STAYED IN CRUISE. PLT CALLED AND ADVISED COMPANY POLICY WAS TO DO WHAT TCAS INDICATED. DON'T MISUNDERSTAND--I FEEL TCAS IS A GREAT TOOL, BUT IN THIS CASE ATC WAS WORKING BOTH ACFT AND TO CLB I FEEL IS WRONG. IS THIS SOMETHING THAT AS A CTLR I MUST BUILD INTO MY SEP STANDARDS OR NOT? PLEASE ADVISE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: DISCUSSED TCAS PROBS. RPTR STATES THIS IS A GROWING PROB AND FEELS IT IS UNSAFE, ESPECIALLY WHEN TFC ISSUED AS KNOWN AND IS AT LEGAL SEP MINIMA. FEELS THAT FAA MUST GET SOME RULES AND REGS OUT QUICKLY SO CTLRS AND FLT CREWS KNOW WHERE THEY STAND. RPTR FEELS THAT PROBLEM EVEN WORSE IN PCA WHERE TFC IS CALLED AT LEGAL MINIMA SEP AND ACFT STILL LEAVE ALT DUE TO TCAS II ALERTS, MOSTLY BASED ON ACFT CLB RATES AND ACFT WILL AND USUALLY LEVEL OFF AT PROPER ALT BELOW TFC. ANALYST COULD ONLY STATE THAT ASRS IS RECEIVING MORE AND MORE RPTS ON ACFT DEVIATING FROM ASSIGNED ALT DUE TO OVERREACTION BY FLT CREWS OR MISALIGNED EQUIP. FAA IS STUDYING PROB, BUT SO FAR NO SOLUTION TO CTLR'S DILEMMA.

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.