Narrative:

While in cruise on airway at FL210 we received a TA on TCASII. TCASII showed traffic approaching from behind and below very rapidly. When the traffic reached 2000 ft below and about 1 mi behind the TA became an RA ordering a maximum climb. I disconnected the autoplt and made a sharp left turn to avoid the conflict and reported the RA to center. I was then advised that a flight of 4 F15's had been cleared to FL200 along the same route of flight. This was my first and only advisory from center. My evasive action was taken in cruise with passenger seat belt sign on. Since we now have 'eyes' for traffic closing from behind via TCASII, it would be very helpful if ATC would advise in advance that the traffic is of a known quantity. This will help avoid unnecessary corrective actions by passenger carrying aircraft. Also military high performance aircraft should avoid high closure rates, when possible, on commercial passenger carrying aircraft.

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Original NASA ASRS Text

Title: MLG ACFT IN CRUISE RECEIVED TCASII RA CAUSED BY FLT OF 4 F15 FIGHTERS CLOSING AT HIGH SPD 1000 FT BELOW RPTR ALT. RPTR CAPT MADE A SHARP L TURN TO EVADE VICE FOLLOWING THE RA TO CLB. RPTR SAYS IT WOULD BE HELPFUL IF ATC WOULD ALERT FLCS IN ADVANCE OF HIGH SPD ACFT CLOSING ON ACR ACFT TO AVOID MAKING ABRUPT MANEUVERS.

Narrative: WHILE IN CRUISE ON AIRWAY AT FL210 WE RECEIVED A TA ON TCASII. TCASII SHOWED TFC APCHING FROM BEHIND AND BELOW VERY RAPIDLY. WHEN THE TFC REACHED 2000 FT BELOW AND ABOUT 1 MI BEHIND THE TA BECAME AN RA ORDERING A MAX CLB. I DISCONNECTED THE AUTOPLT AND MADE A SHARP L TURN TO AVOID THE CONFLICT AND RPTED THE RA TO CTR. I WAS THEN ADVISED THAT A FLT OF 4 F15'S HAD BEEN CLRED TO FL200 ALONG THE SAME RTE OF FLT. THIS WAS MY FIRST AND ONLY ADVISORY FROM CTR. MY EVASIVE ACTION WAS TAKEN IN CRUISE WITH PAX SEAT BELT SIGN ON. SINCE WE NOW HAVE 'EYES' FOR TFC CLOSING FROM BEHIND VIA TCASII, IT WOULD BE VERY HELPFUL IF ATC WOULD ADVISE IN ADVANCE THAT THE TFC IS OF A KNOWN QUANTITY. THIS WILL HELP AVOID UNNECESSARY CORRECTIVE ACTIONS BY PAX CARRYING ACFT. ALSO MIL HIGH PERFORMANCE ACFT SHOULD AVOID HIGH CLOSURE RATES, WHEN POSSIBLE, ON COMMERCIAL PAX CARRYING ACFT.

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.