Narrative:

Air carrier X approaching san juan, pr, from saalr intersection. 12 DME northwest of airport heading 180 degrees, descending from 3000 ft to assigned altitude 2200 ft. Air carrier Y was at our 2 O'clock, about 2 mi west of us (estimated) and about same altitude. ATC told Y to turn to heading 050 degrees. Followed by an instruction to us to turn heading 280 degrees. It was VFR and we could see immediate conflict if we complied, so we did not, we maintained heading 180 degrees. Y made turn to 050 degrees and passed abeam our right side, climbing. Of course, Y could not see us till his turn nearly completed. TCASII TA/RA worked for descent then monitor vertical speed, we complied. We continued in to localizer runway 10, called field in sight and landed runway 10. I did not personally contact ATC upon landing. Do not know reasons for turn instructions given us. Supplemental information from acn 296473: nnw of sju we were heading south descending to 2200 ft for the lagoon visual approach to runway 8. We noticed a 727 about 1 O'clock which appeared to be heading east on the runway 10 localizer. That aircraft turned out to be air carrier Y. As we approached 3000 ft and began to slow down, ATC gave Y a left turn to 050 degrees, putting him on a rapidly converging course with us, although he was still banking to the right. ATC then gave us an immediate right turn to 280 degrees. I started but judged that we may cross paths and be belly up to Y if I continued the turn. I rolled back left and said to the captain I'm not turning right. Before I completed the sentence we got a TCASII 'descend, descend now' command. I stopped our turn and followed the TCASII vsi commands down while the captain informed ATC. Y passed off to our right above us and climbing.

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Original NASA ASRS Text

Title: ACR X TCASII TA RA NON ADHERENCE TO ATC CLRNC HAD POSSIBLE LTSS FROM ACR Y. EVASIVE ACTION DSND.

Narrative: ACR X APCHING SAN JUAN, PR, FROM SAALR INTXN. 12 DME NW OF ARPT HDG 180 DEGS, DSNDING FROM 3000 FT TO ASSIGNED ALT 2200 FT. ACR Y WAS AT OUR 2 O'CLOCK, ABOUT 2 MI W OF US (ESTIMATED) AND ABOUT SAME ALT. ATC TOLD Y TO TURN TO HDG 050 DEGS. FOLLOWED BY AN INSTRUCTION TO US TO TURN HDG 280 DEGS. IT WAS VFR AND WE COULD SEE IMMEDIATE CONFLICT IF WE COMPLIED, SO WE DID NOT, WE MAINTAINED HDG 180 DEGS. Y MADE TURN TO 050 DEGS AND PASSED ABEAM OUR R SIDE, CLBING. OF COURSE, Y COULD NOT SEE US TILL HIS TURN NEARLY COMPLETED. TCASII TA/RA WORKED FOR DSCNT THEN MONITOR VERT SPD, WE COMPLIED. WE CONTINUED IN TO LOC RWY 10, CALLED FIELD IN SIGHT AND LANDED RWY 10. I DID NOT PERSONALLY CONTACT ATC UPON LNDG. DO NOT KNOW REASONS FOR TURN INSTRUCTIONS GIVEN US. SUPPLEMENTAL INFO FROM ACN 296473: NNW OF SJU WE WERE HDG S DSNDING TO 2200 FT FOR THE LAGOON VISUAL APCH TO RWY 8. WE NOTICED A 727 ABOUT 1 O'CLOCK WHICH APPEARED TO BE HDG E ON THE RWY 10 LOC. THAT ACFT TURNED OUT TO BE ACR Y. AS WE APCHED 3000 FT AND BEGAN TO SLOW DOWN, ATC GAVE Y A L TURN TO 050 DEGS, PUTTING HIM ON A RAPIDLY CONVERGING COURSE WITH US, ALTHOUGH HE WAS STILL BANKING TO THE R. ATC THEN GAVE US AN IMMEDIATE R TURN TO 280 DEGS. I STARTED BUT JUDGED THAT WE MAY CROSS PATHS AND BE BELLY UP TO Y IF I CONTINUED THE TURN. I ROLLED BACK L AND SAID TO THE CAPT I'M NOT TURNING R. BEFORE I COMPLETED THE SENTENCE WE GOT A TCASII 'DSND, DSND NOW' COMMAND. I STOPPED OUR TURN AND FOLLOWED THE TCASII VSI COMMANDS DOWN WHILE THE CAPT INFORMED ATC. Y PASSED OFF TO OUR R ABOVE US AND CLBING.

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.