Narrative:

Air carrier X medium large transport is assigned runway heading with air carrier Y medium large transport 1-2 mi behind and assigned 270 degrees (runway heading is 300 degrees). Air carrier Y is issued climb to 7000' and acknowledgement is received. Air carrier X is issued climb to 7000' and acknowledgement is received. Air carrier Y is issued left turn, heading 180 degrees (air carrier Y couldn't be issued climb and turn due to approach sectorization). Acknowledgement is received in the following form: '180.' air carrier X was issued a left turn heading 220 degrees. After it became clear (aircraft's track) that air carrier Y was still heading west, air carrier X was issued traffic and asked if he could maintain visibility sep from air carrier Y. Air carrier X advised, 'we're doing it.' air carrier Y, who was out of 4700', we issued, 'maintain 5000'.' his response was, 'we're out of 5200' (I can only imagine that the problem was computer lag time). Air carrier Y had also been issued a left turn heading 150 degrees. Air carrier Y, during the course of events, had gone from air carrier X's left to right, with pdl out of 6000' and climbing to 7000', as previously assigned. Air carrier Y, on the other hand, was issued a turn and an altitude (heading 150 degrees and maintain 5000'), but took it upon himself to continue the climb along with the turn. When I observed air carrier Y out of 5600' I reissued traffic and ensured visibility could be maintained, and climbed air carrier Y to 10000' and switched him to next facility. I would add that upon examination of tapes, it was evident air carrier Y was not doing a very good job of listening--when the turn to 180 degrees was issued, someone answered, but who was not confirmed by me. Air carrier Y was called 3 times and asked or retold about the turn to 180 degrees, with no reply twice. Also, if there was a problem with understanding altitude assignment, I should have been queried.

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Original NASA ASRS Text

Title: ACR Y FLT CREW FAILED TO FOLLOW ATC INSTRUCTIONS AND CLRNC. PLT DEVIATION.

Narrative: ACR X MLG IS ASSIGNED RWY HDG WITH ACR Y MLG 1-2 MI BEHIND AND ASSIGNED 270 DEGS (RWY HDG IS 300 DEGS). ACR Y IS ISSUED CLB TO 7000' AND ACKNOWLEDGEMENT IS RECEIVED. ACR X IS ISSUED CLB TO 7000' AND ACKNOWLEDGEMENT IS RECEIVED. ACR Y IS ISSUED LEFT TURN, HDG 180 DEGS (ACR Y COULDN'T BE ISSUED CLB AND TURN DUE TO APCH SECTORIZATION). ACKNOWLEDGEMENT IS RECEIVED IN THE FOLLOWING FORM: '180.' ACR X WAS ISSUED A LEFT TURN HDG 220 DEGS. AFTER IT BECAME CLEAR (ACFT'S TRACK) THAT ACR Y WAS STILL HDG W, ACR X WAS ISSUED TFC AND ASKED IF HE COULD MAINTAIN VIS SEP FROM ACR Y. ACR X ADVISED, 'WE'RE DOING IT.' ACR Y, WHO WAS OUT OF 4700', WE ISSUED, 'MAINTAIN 5000'.' HIS RESPONSE WAS, 'WE'RE OUT OF 5200' (I CAN ONLY IMAGINE THAT THE PROB WAS COMPUTER LAG TIME). ACR Y HAD ALSO BEEN ISSUED A LEFT TURN HDG 150 DEGS. ACR Y, DURING THE COURSE OF EVENTS, HAD GONE FROM ACR X'S LEFT TO RIGHT, WITH PDL OUT OF 6000' AND CLBING TO 7000', AS PREVIOUSLY ASSIGNED. ACR Y, ON THE OTHER HAND, WAS ISSUED A TURN AND AN ALT (HDG 150 DEGS AND MAINTAIN 5000'), BUT TOOK IT UPON HIMSELF TO CONTINUE THE CLB ALONG WITH THE TURN. WHEN I OBSERVED ACR Y OUT OF 5600' I REISSUED TFC AND ENSURED VIS COULD BE MAINTAINED, AND CLBED ACR Y TO 10000' AND SWITCHED HIM TO NEXT FAC. I WOULD ADD THAT UPON EXAMINATION OF TAPES, IT WAS EVIDENT ACR Y WAS NOT DOING A VERY GOOD JOB OF LISTENING--WHEN THE TURN TO 180 DEGS WAS ISSUED, SOMEONE ANSWERED, BUT WHO WAS NOT CONFIRMED BY ME. ACR Y WAS CALLED 3 TIMES AND ASKED OR RETOLD ABOUT THE TURN TO 180 DEGS, WITH NO REPLY TWICE. ALSO, IF THERE WAS A PROB WITH UNDERSTANDING ALT ASSIGNMENT, I SHOULD HAVE BEEN QUERIED.

Data retrieved from NASA's ASRS site as of August 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.