Narrative:

A near miss occurred during a functional check flight of an F15 aircraft. The air-to-ground radar mapping and weapons delivery symbology was being checked at the time against a bridge on the mississippi river in a descent of about 20 degrees from approximately 8000 ft altitude on a heading of 350 degrees magnetic. Speed 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 traffic and is within the agreed upon operating area for low altitude/high speed operations below 10000 ft per agreement with the FAA. When established in the descent, 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 aircraft (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 aircraft and cleared it by several hundred ft of altitude. I circled back to re-observe the aircraft from about 8000 ft and saw it still proceeding easterly to my southeast. I inquired of ZKC if they showed any traffic to my southeast, none was seen, although they did report another airplane about 5 mi northwest. It is quite possible that the near-miss aircraft was below the field of view of the center's radar, although it is unknown whether it was squawking 1200. Better radar coverage and a requirement for universal transponder usage would have benefitted in this case since, in our operations, we always request TA's from ATC. The time of day may have also increased the probability of other traffic since it was a nice day and about XE15 pm (after normal working hours). Also, it is important to emphasize that relative motion is the main eye-catching cue to alert the pilot to other traffic. On a potential midair collision, there is no relative motion and maintenance of a good scan pattern is therefore paramount.

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Original NASA ASRS Text

Title: 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.

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.