Narrative:

Air carrier X while in cruise at FL290 5-10 mi northeast of bld VOR, a military fgt passed approximately 200 ft above and 1500 ft to the left of our aircraft. Military fgt appeared to be in a slight climb, maneuvering to his right. Our TCASII issued a TA and showed the fgt altitude to be FL292. The TCASII also showed the target descending after passing, to FL280. ZLA said that the fgt had been tracked at FL280 for the last 150 mi. A passenger on board reported seeing a military jet at our altitude and then descending, approximately 400 yards left of our aircraft.

Google
 

Original NASA ASRS Text

Title: ACR X TCASII TA WITH MIL FGT POSSIBLE LTSS. PLTDEV.

Narrative: ACR X WHILE IN CRUISE AT FL290 5-10 MI NE OF BLD VOR, A MIL FGT PASSED APPROX 200 FT ABOVE AND 1500 FT TO THE L OF OUR ACFT. MIL FGT APPEARED TO BE IN A SLIGHT CLB, MANEUVERING TO HIS R. OUR TCASII ISSUED A TA AND SHOWED THE FGT ALT TO BE FL292. THE TCASII ALSO SHOWED THE TARGET DSNDING AFTER PASSING, TO FL280. ZLA SAID THAT THE FGT HAD BEEN TRACKED AT FL280 FOR THE LAST 150 MI. A PAX ON BOARD RPTED SEEING A MIL JET AT OUR ALT AND THEN DSNDING, APPROX 400 YARDS L OF OUR 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.