Narrative:

Air carrier X during descent on STAR into rdu, I encountered a flight of F-15's. I was cleared to cross argal at 10000 ft and 250 KIAS. Rdu approach called out a flight of 3 F-15's at 11 O'clock and 4 mi, nebound, last reported altitude was 11500 ft, and suggested leveling at 12000 ft until passing the aircraft. Initially, no traffic was depicted on the TCASII. A target was then displayed at 11:30 and 3 mi. I soon spotted the F-15 flight leader, who appeared to be at 11500 ft, based on TCASII altitude information. We continued descending out of 13000 ft and noticed a second F-15 at about 13500 ft, 11:30 O'clock position and 1/2 mi. The third F-15 was not spotted visually. Only the lead F-15 was operating his transponder, so he was the only target displayed on TCASII. No evasive action was needed since I was descending when I spotted the second F-15, but we got closer to the aircraft than was appropriate. The controller stated that the flight of 3 was designated as military Y and they were en route to vr 5415. To minimize the chances for a midair collision I don't believe the F-15's should operate VFR and if the formation is not tight, all aircraft in the flight should operate their xponders. If the geometry of this incident was slightly different, an RA from the TCASII on the flight leader could have caused us to climb into the wingman. I don't believe that this is an isolated incident, and that procedural changes are necessary.

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Original NASA ASRS Text

Title: ACR X TCASII TA HAD CONFLICT WITH A FLT OF MIL FGTS. SEE AND AVOID CONCEPT.

Narrative: ACR X DURING DSCNT ON STAR INTO RDU, I ENCOUNTERED A FLT OF F-15'S. I WAS CLRED TO CROSS ARGAL AT 10000 FT AND 250 KIAS. RDU APCH CALLED OUT A FLT OF 3 F-15'S AT 11 O'CLOCK AND 4 MI, NEBOUND, LAST RPTED ALT WAS 11500 FT, AND SUGGESTED LEVELING AT 12000 FT UNTIL PASSING THE ACFT. INITIALLY, NO TFC WAS DEPICTED ON THE TCASII. A TARGET WAS THEN DISPLAYED AT 11:30 AND 3 MI. I SOON SPOTTED THE F-15 FLT LEADER, WHO APPEARED TO BE AT 11500 FT, BASED ON TCASII ALT INFO. WE CONTINUED DSNDING OUT OF 13000 FT AND NOTICED A SECOND F-15 AT ABOUT 13500 FT, 11:30 O'CLOCK POS AND 1/2 MI. THE THIRD F-15 WAS NOT SPOTTED VISUALLY. ONLY THE LEAD F-15 WAS OPERATING HIS XPONDER, SO HE WAS THE ONLY TARGET DISPLAYED ON TCASII. NO EVASIVE ACTION WAS NEEDED SINCE I WAS DSNDING WHEN I SPOTTED THE SECOND F-15, BUT WE GOT CLOSER TO THE ACFT THAN WAS APPROPRIATE. THE CTLR STATED THAT THE FLT OF 3 WAS DESIGNATED AS MIL Y AND THEY WERE ENRTE TO VR 5415. TO MINIMIZE THE CHANCES FOR A MIDAIR COLLISION I DON'T BELIEVE THE F-15'S SHOULD OPERATE VFR AND IF THE FORMATION IS NOT TIGHT, ALL ACFT IN THE FLT SHOULD OPERATE THEIR XPONDERS. IF THE GEOMETRY OF THIS INCIDENT WAS SLIGHTLY DIFFERENT, AN RA FROM THE TCASII ON THE FLT LEADER COULD HAVE CAUSED US TO CLB INTO THE WINGMAN. I DON'T BELIEVE THAT THIS IS AN ISOLATED INCIDENT, AND THAT PROCEDURAL CHANGES ARE NECESSARY.

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.