37000 Feet

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ZME controller described a near separation-loss event when traffic made an unexpected turn conflicting with other traffic; the reporter noting unusual instructions should be coordinated and confirmed prior to execution.

Narrative:

A MD88 was at FL340 approaching bna northwest bound. An A320 at FL350 was southwest of bna; flying southeast bound. I descended the MD88 to FL330. I was busy sequencing other aircraft and performing other ATC duties when I noticed the A320 turning northeast back towards bna. I asked the controller who had worked the aircraft what the aircraft was doing and I was told 'going back to bna like it says in the flight plan'. At that moment the A320 said he was responding to an RA and was climbing back up. Immediately after that; the MD88 said he was responding to an RA and was descending. Both aircraft separated themselves. I issued no control instructions until both aircraft returned to their assigned altitudes. During a typical sequence push for atl; it is common for controllers to leave aircraft on headings and let the last controller in the facility 'tweak' the sequence. In this instance I was not expecting the controller to force the A320 to turn 90 degrees left or more to go back over bna. The aircraft was already passed bna and I 'assumed' the aircraft was on a heading. I was expecting the aircraft to be left on a heading for me to 'tweak' for the sequence. Asking other controllers in the area I got the same opinions: the turn back to bna was not expected and not common. Recommendation: confirm and discuss with next/previous controller unusual control instructions that would be out of the ordinary or contrary to past practices.

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Original NASA ASRS Text

Title: ZME Controller described a near separation-loss event when traffic made an unexpected turn conflicting with other traffic; the reporter noting unusual instructions should be coordinated and confirmed prior to execution.

Narrative: A MD88 was at FL340 approaching BNA northwest bound. An A320 at FL350 was southwest of BNA; flying southeast bound. I descended the MD88 to FL330. I was busy sequencing other aircraft and performing other ATC duties when I noticed the A320 turning northeast back towards BNA. I asked the Controller who had worked the aircraft what the aircraft was doing and I was told 'going back to BNA like it says in the flight plan'. At that moment the A320 said he was responding to an RA and was climbing back up. Immediately after that; the MD88 said he was responding to an RA and was descending. Both aircraft separated themselves. I issued no control instructions until both aircraft returned to their assigned altitudes. During a typical sequence push for ATL; it is common for Controllers to leave aircraft on headings and let the last Controller in the facility 'tweak' the sequence. In this instance I was not expecting the Controller to force the A320 to turn 90 degrees left or more to go back over BNA. The aircraft was already passed BNA and I 'assumed' the aircraft was on a heading. I was expecting the aircraft to be left on a heading for me to 'tweak' for the sequence. Asking other Controllers in the area I got the same opinions: the turn back to BNA was not expected and not common. Recommendation: confirm and discuss with next/previous Controller unusual control instructions that would be out of the ordinary or contrary to past practices.

Data retrieved from NASA's ASRS site as of April 2012 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.