Narrative:

Descended from FL270 to FL260 as required by TCASII alert. Climbed back to FL270 when issued 'clear of conflict.' advised ATC.

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Original NASA ASRS Text

Title: MD80 ZAU UNDEFINED TCASII MANEUVER.

Narrative: DSNDED FROM FL270 TO FL260 AS REQUIRED BY TCASII ALERT. CLBED BACK TO FL270 WHEN ISSUED 'CLR OF CONFLICT.' ADVISED ATC.

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.