Narrative:

Air carrier X was inbound to seatac on the olympia 1 STAR, level at 10000 ft (under my control). Air carrier Y departed for sfo on the ellma departure SID, climbing to assigned altitude of 9000 ft. Approximately 14 mi southwest of sea, I issued traffic to air carrier X, that the air carrier Y was leveling 9000 ft. Air carrier X reported after a few seconds that they were descending. I again told air carrier X to maintain 10000 ft. Air carrier X responded, 'ok, we've got an alert saying go down.' simultaneously, air carrier Y was getting an alert to climb. They both followed the TCASII and almost collided. Later, air carrier X pilot indicated his TCASII was showing 0 separation. They passed in the clouds without seeing each other. When pilots start taking evasive action, our equipment cannot update quick enough for the controller to help. Both aircraft were issued traffic as prescribed by our handbook (merging target procedures). Company directives, I'm told, dictate that pilots must respond/follow the TCASII alert advisories. Supplemental information from acn 224982: air carrier Y departed sea swbound climbing to 9000 ft, was issued traffic to his 11 O'clock, level at 10000 ft. Air carrier Y was TCASII alerted to the traffic at 10000 ft. The alert advised pilot to climb. Air carrier Y climbed through traffic. Traffic for air carrier Y was air carrier X with TCASII also, air carrier X was nebound. This event was a result of pre-implementation of the TCASII for political reasons and company policy dictates use of the TCASII. Pilots can now disregard ATC instructions based on TCASII alerts -- even if the controller has issued traffic to that aircraft and has applied the correct separation! Supplemental information from acn 224912: air carrier X received a TA annunciation followed by immediate RA. Annunciation was descend crossing descend. We immediately pushed over following RA to 2000- 2500 FPM descent. Intruder was showing 1200-1230, 800 ft below, climbing. I instructed first officer to advise ATC of descent. ATC advised intruder was air carrier who was on a different frequency (128.3?) and that he was leveling off. Controller advised us to level and then climb. Both aircraft passed to each other's right on the same altitude, approximately 9700 ft. Lowest altitude achieved was 9650 ft. During event things got confusing. RA called for descent and then increased descent. ATC is calling for a level off followed by immediate climb. RA shows intruder at 00 altitude. The TCASII system requires both aircraft to comply with RA. If one does not comply, the solution will not provide a safe separation. Procedures need to be developed to ensure compliance by crews in the event of RA. ATC's role in the solution of conflict needs to be defined when using this system. On landing, the ATC supervisor indicated the air carrier Y was cleared to 9000 ft.

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Original NASA ASRS Text

Title: ACR X AND Y NON ADHERENCE TO ATC CLRNC. ACR X TCASII TA RA DSND, ACY Y TCASII RA CLB TO OCCUPIED ALT HAD NMAC LTSS. EVASIVE ACTION TAKEN. NON ADHERENCE TO ATC INSTRUCTION.

Narrative: ACR X WAS INBOUND TO SEATAC ON THE OLYMPIA 1 STAR, LEVEL AT 10000 FT (UNDER MY CTL). ACR Y DEPARTED FOR SFO ON THE ELLMA DEP SID, CLBING TO ASSIGNED ALT OF 9000 FT. APPROX 14 MI SW OF SEA, I ISSUED TFC TO ACR X, THAT THE ACR Y WAS LEVELING 9000 FT. ACR X RPTED AFTER A FEW SECONDS THAT THEY WERE DSNDING. I AGAIN TOLD ACR X TO MAINTAIN 10000 FT. ACR X RESPONDED, 'OK, WE'VE GOT AN ALERT SAYING GO DOWN.' SIMULTANEOUSLY, ACR Y WAS GETTING AN ALERT TO CLB. THEY BOTH FOLLOWED THE TCASII AND ALMOST COLLIDED. LATER, ACR X PLT INDICATED HIS TCASII WAS SHOWING 0 SEPARATION. THEY PASSED IN THE CLOUDS WITHOUT SEEING EACH OTHER. WHEN PLTS START TAKING EVASIVE ACTION, OUR EQUIP CANNOT UPDATE QUICK ENOUGH FOR THE CTLR TO HELP. BOTH ACFT WERE ISSUED TFC AS PRESCRIBED BY OUR HANDBOOK (MERGING TARGET PROCS). COMPANY DIRECTIVES, I'M TOLD, DICTATE THAT PLTS MUST RESPOND/FOLLOW THE TCASII ALERT ADVISORIES. SUPPLEMENTAL INFO FROM ACN 224982: ACR Y DEPARTED SEA SWBOUND CLBING TO 9000 FT, WAS ISSUED TFC TO HIS 11 O'CLOCK, LEVEL AT 10000 FT. ACR Y WAS TCASII ALERTED TO THE TFC AT 10000 FT. THE ALERT ADVISED PLT TO CLB. ACR Y CLBED THROUGH TFC. TFC FOR ACR Y WAS ACR X WITH TCASII ALSO, ACR X WAS NEBOUND. THIS EVENT WAS A RESULT OF PRE-IMPLEMENTATION OF THE TCASII FOR POLITICAL REASONS AND COMPANY POLICY DICTATES USE OF THE TCASII. PLTS CAN NOW DISREGARD ATC INSTRUCTIONS BASED ON TCASII ALERTS -- EVEN IF THE CTLR HAS ISSUED TFC TO THAT ACFT AND HAS APPLIED THE CORRECT SEPARATION! SUPPLEMENTAL INFO FROM ACN 224912: ACR X RECEIVED A TA ANNUNCIATION FOLLOWED BY IMMEDIATE RA. ANNUNCIATION WAS DSND XING DSND. WE IMMEDIATELY PUSHED OVER FOLLOWING RA TO 2000- 2500 FPM DSCNT. INTRUDER WAS SHOWING 1200-1230, 800 FT BELOW, CLBING. I INSTRUCTED FO TO ADVISE ATC OF DSCNT. ATC ADVISED INTRUDER WAS ACR WHO WAS ON A DIFFERENT FREQ (128.3?) AND THAT HE WAS LEVELING OFF. CTLR ADVISED US TO LEVEL AND THEN CLB. BOTH ACFT PASSED TO EACH OTHER'S R ON THE SAME ALT, APPROX 9700 FT. LOWEST ALT ACHIEVED WAS 9650 FT. DURING EVENT THINGS GOT CONFUSING. RA CALLED FOR DSCNT AND THEN INCREASED DSCNT. ATC IS CALLING FOR A LEVEL OFF FOLLOWED BY IMMEDIATE CLB. RA SHOWS INTRUDER AT 00 ALT. THE TCASII SYS REQUIRES BOTH ACFT TO COMPLY WITH RA. IF ONE DOES NOT COMPLY, THE SOLUTION WILL NOT PROVIDE A SAFE SEPARATION. PROCS NEED TO BE DEVELOPED TO ENSURE COMPLIANCE BY CREWS IN THE EVENT OF RA. ATC'S ROLE IN THE SOLUTION OF CONFLICT NEEDS TO BE DEFINED WHEN USING THIS SYS. ON LNDG, THE ATC SUPVR INDICATED THE ACR Y WAS CLRED TO 9000 FT.

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.