Narrative:

Air carrier X was swbnd at FL240. Fgt Y was sebnd at FL250, passing over air carrier X. To separate fgt Y from another aircraft, Y was given this clearance, 'Y descend and maintain FL240, correction fgt Y maintain FL250 and turn 30 degrees right, vector for traffic.' fgt Y did not acknowledge until 21 seconds later, and his readback was, 'fgt Y out of 250 for 240.' controller immediately corrected the aircraft and cleared Y to maintain FL250 and turn 30 degrees right once again. Fgt Y then climbed to FL250, but had descended to FL247 causing a sep error with air carrier X approximately 2.5 mi away.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN ACR AND FLT OF 2 NAVY FGT ACFT. OPERATION ERROR.

Narrative: ACR X WAS SWBND AT FL240. FGT Y WAS SEBND AT FL250, PASSING OVER ACR X. TO SEPARATE FGT Y FROM ANOTHER ACFT, Y WAS GIVEN THIS CLRNC, 'Y DSND AND MAINTAIN FL240, CORRECTION FGT Y MAINTAIN FL250 AND TURN 30 DEGS RIGHT, VECTOR FOR TFC.' FGT Y DID NOT ACKNOWLEDGE UNTIL 21 SECS LATER, AND HIS READBACK WAS, 'FGT Y OUT OF 250 FOR 240.' CTLR IMMEDIATELY CORRECTED THE ACFT AND CLRED Y TO MAINTAIN FL250 AND TURN 30 DEGS RIGHT ONCE AGAIN. FGT Y THEN CLBED TO FL250, BUT HAD DSNDED TO FL247 CAUSING A SEP ERROR WITH ACR X APPROX 2.5 MI AWAY.

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.