F15 PLT HAS NMAC WITH TWIN CESSNA ACFT WHILE ON TACTICAL MANEUVERS CHKING AIR TO GND RADAR MAPPING SYMBOLOGY.

Narrative

A NEAR MISS OCCURRED DURING A FUNCTIONAL CHK FLT OF AN F15 ACFT. THE AIR-TO-GND RADAR MAPPING AND WEAPONS DELIVERY SYMBOLOGY WAS BEING CHKED AT THE TIME AGAINST A BRIDGE ON THE MISSISSIPPI RIVER IN A DSCNT OF ABOUT 20 DEGS FROM APPROX 8000 FT ALT ON A HDG OF 350 DEGS MAGNETIC. SPD WAS ABOUT 400 KT WHICH ENSURES A GOOD MANEUVER MARGIN. THIS TARGET HAS BEEN USED FOR MANY YRS BECAUSE IT IS A RADAR SIGNIFICANT; SEES LITTLE AIR TFC AND IS WITHIN THE AGREED UPON OPERATING AREA FOR LOW ALT/HIGH SPD OPS BELOW 10000 FT PER AGREEMENT WITH THE FAA. WHEN ESTABLISHED IN THE DSCNT; THE DESIGNATION SYMBOLOGY WAS SLIGHTLY OFF; AND I HAD JUST VISUALLY REDESIGNATED ON THE BRIDGE. IMMEDIATELY THEREAFTER; I NOTICED A SPECK STARTING TO GROW AT ABOUT 10:30 O'CLOCK CODE SLIGHTLY BELOW MY TRAJECTORY WHICH APPEARED TO BE A TWIN-ENGINED LIGHT CIVIL ACFT (CESSNA?) PROCEEDING EASTERLY AT 3500 FT AND ON A VIRTUAL COLLISION COURSE; JUDGING FROM THE LACK OF RELATIVE MOTION. I PULLED BACK ON THE STICK RAPIDLY TO AVOID THE ACFT AND CLRED IT BY SEVERAL HUNDRED FT OF ALT. I CIRCLED BACK TO RE-OBSERVE THE ACFT FROM ABOUT 8000 FT AND SAW IT STILL PROCEEDING EASTERLY TO MY SE. I INQUIRED OF ZKC IF THEY SHOWED ANY TFC TO MY SE; NONE WAS SEEN; ALTHOUGH THEY DID RPT ANOTHER AIRPLANE ABOUT 5 MI NW. IT IS QUITE POSSIBLE THAT THE NEAR-MISS ACFT WAS BELOW THE FIELD OF VIEW OF THE CTR'S RADAR; ALTHOUGH IT IS UNKNOWN WHETHER IT WAS SQUAWKING 1200. BETTER RADAR COVERAGE AND A REQUIREMENT FOR UNIVERSAL XPONDER USAGE WOULD HAVE BENEFITTED IN THIS CASE SINCE; IN OUR OPS; WE ALWAYS REQUEST TA'S FROM ATC. THE TIME OF DAY MAY HAVE ALSO INCREASED THE PROBABILITY OF OTHER TFC SINCE IT WAS A NICE DAY AND ABOUT XE15 PM (AFTER NORMAL WORKING HRS). ALSO; IT IS IMPORTANT TO EMPHASIZE THAT RELATIVE MOTION IS THE MAIN EYE-CATCHING CUE TO ALERT THE PLT TO OTHER TFC. ON A POTENTIAL MIDAIR COLLISION; THERE IS NO RELATIVE MOTION AND MAINT OF A GOOD SCAN PATTERN IS THEREFORE PARAMOUNT.