Narrative:

Aircraft X in cruise at FL350, received TCASII, noted target 1100 ft below, converging and climbing. Called anc on 133.6 immediately and reported conflict and intention to climb. Aircraft Y responded that they were stopping climb and descending. Closest encounter was 2 mi, 800 ft vertical, and vertical separation increased to more than 1000 ft as aircraft Y passed underneath. We did not climb (no RA) because vertical closure stopped and began increasing. Aircraft Y resumed climb to FL370 after he passed underneath us. Recommendation: 1) FAA/ARTCC computer early recognition software to identify conflicting clrncs long before conflict occurs. 2) I am recommending to aircraft X company that we enact policy immediately to make altitude calls mandatory, even when contacting same controller on a new frequency in same controller's airspace. Situational awareness to other crews. 3) FAA review policy to ensure all pilots report altitude on initial call to same controller after frequency change. Note: #2 and #3 refer mostly to nights when 1 controller controls several sectors. Supplemental information from acn 415652: climbing out of panc to FL370, noticed TCASII traffic at 25 mi at FL350. At FL335, noticed he was getting unusually close. We started to level off and then descended to avoid conflict. ATC and other aircraft noticed situation at about same time. Other aircraft said they were climbing and ATC told us to descend, which we were already doing. Our peak altitude was FL339. After conflict was clear, ATC again cleared us to continue climb to FL370. During this we had a 'non threatening proximity traffic' TCASII alert. Possible factors: 1) anc radar had some outages during that time frame which may or may not have been a factor. Other aircraft may have been flying from a non radar environment. 2) controller was talking to other aircraft and I think he was controling other aircraft on a separate radio frequency, which sometimes makes communication a little more difficult.

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Original NASA ASRS Text

Title: ACR MD80 FLC OBSERVES TCASII TFC CLBING FROM BENEATH IN APPARENT CONFLICT WITH THEM AND NOTIFIES ARTCC RADAR CTLR. CLBING B757 ALSO RECEIVES TCASII ALERT AND STOPS CLB. AFTER CONFLICT IS RESOLVED CTLR CLBS B757 TO HIGHER ALT. PICS OF BOTH ACFT STATE RECOMMENDATIONS TO CORRECT INCIDENT.

Narrative: ACFT X IN CRUISE AT FL350, RECEIVED TCASII, NOTED TARGET 1100 FT BELOW, CONVERGING AND CLBING. CALLED ANC ON 133.6 IMMEDIATELY AND RPTED CONFLICT AND INTENTION TO CLB. ACFT Y RESPONDED THAT THEY WERE STOPPING CLB AND DSNDING. CLOSEST ENCOUNTER WAS 2 MI, 800 FT VERT, AND VERT SEPARATION INCREASED TO MORE THAN 1000 FT AS ACFT Y PASSED UNDERNEATH. WE DID NOT CLB (NO RA) BECAUSE VERT CLOSURE STOPPED AND BEGAN INCREASING. ACFT Y RESUMED CLB TO FL370 AFTER HE PASSED UNDERNEATH US. RECOMMENDATION: 1) FAA/ARTCC COMPUTER EARLY RECOGNITION SOFTWARE TO IDENT CONFLICTING CLRNCS LONG BEFORE CONFLICT OCCURS. 2) I AM RECOMMENDING TO ACFT X COMPANY THAT WE ENACT POLICY IMMEDIATELY TO MAKE ALT CALLS MANDATORY, EVEN WHEN CONTACTING SAME CTLR ON A NEW FREQ IN SAME CTLR'S AIRSPACE. SITUATIONAL AWARENESS TO OTHER CREWS. 3) FAA REVIEW POLICY TO ENSURE ALL PLTS RPT ALT ON INITIAL CALL TO SAME CTLR AFTER FREQ CHANGE. NOTE: #2 AND #3 REFER MOSTLY TO NIGHTS WHEN 1 CTLR CTLS SEVERAL SECTORS. SUPPLEMENTAL INFO FROM ACN 415652: CLBING OUT OF PANC TO FL370, NOTICED TCASII TFC AT 25 MI AT FL350. AT FL335, NOTICED HE WAS GETTING UNUSUALLY CLOSE. WE STARTED TO LEVEL OFF AND THEN DSNDED TO AVOID CONFLICT. ATC AND OTHER ACFT NOTICED SIT AT ABOUT SAME TIME. OTHER ACFT SAID THEY WERE CLBING AND ATC TOLD US TO DSND, WHICH WE WERE ALREADY DOING. OUR PEAK ALT WAS FL339. AFTER CONFLICT WAS CLR, ATC AGAIN CLRED US TO CONTINUE CLB TO FL370. DURING THIS WE HAD A 'NON THREATENING PROX TFC' TCASII ALERT. POSSIBLE FACTORS: 1) ANC RADAR HAD SOME OUTAGES DURING THAT TIME FRAME WHICH MAY OR MAY NOT HAVE BEEN A FACTOR. OTHER ACFT MAY HAVE BEEN FLYING FROM A NON RADAR ENVIRONMENT. 2) CTLR WAS TALKING TO OTHER ACFT AND I THINK HE WAS CTLING OTHER ACFT ON A SEPARATE RADIO FREQ, WHICH SOMETIMES MAKES COM A LITTLE MORE DIFFICULT.

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.