Narrative:

I was on an IFR flight plan enroute to jackson; tn (mkl) at 6000 MSL. Although most of the route was VMC; I was dealing with a stiff headwind and occasional light turbulence.the aircraft appeared to be maneuvering about 5 NM southwest of my position; at altitudes varying from about 500 feet above to about 500 feet below my assigned altitude. Memphis center confirmed the other aircraft's position; but was not in contact with the other crew.based on the other aircraft's speed and maneuverability; I had the impression that it was a light jet (perhaps a small citation); but we never got close enough to confirm that identification.at about XA18Z; the other aircraft changed course towards my position; and center approved a deviation to the right of about 20deg. After about 90 seconds; center cleared me direct to mkl. I believe it was about this point that I was handed off to another memphis center controller.at approximately XA21Z; the other aircraft once more changed course towards my position. With center's approval; I deviated to the right for about two minutes before being cleared direct to mkl.at about XA30Z; the other aircraft again headed towards my position and center approved a deviation to the right. After about four minutes; center cleared me direct to mkl and told me to descend to 4000 feet. At approximately XA45Z; what I believe was the same aircraft again headed toward me; but this time (if I remember correctly) it appeared he was about at my altitude and at my 6 o'clock position. When he got within about two miles; I attempted to contact center but the controller was busy talking to other aircraft. When my traffic advisory system indicated that the other aircraft was within about a mile of my position and closing rapidly; I took evasive action by turning about 60 degrees to the left of my course. As soon as the frequency opened up; I advised memphis center I had again changed heading to avoid the other aircraft. (In retrospect; I should have used the phrase 'evasive action' to emphasize how serious I considered the situation.) I also advised the controller that I was concerned that I would soon approach my minimum fuel level (if I remember correctly; inadvertently using the phrase 'critical fuel').the controller voiced no objection to my actions; assured me there would be no further delays and gave me a vector towards mkl. A few minutes later; he cleared me for the visual approach to rwy 20 and handed me off to mkl tower. The rest of the flight was uneventful. (Once on the ground at mkl; I asked and tower said he had not been in contact with the other traffic.)I can't recall having to deviate so many times for another aircraft. As they weren't talking to memphis center; I can only speculate why the other crew maneuvered as they did. In any event; under the circumstances; I felt I had no alternative but to take evasive action.

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Original NASA ASRS Text

Title: General aviation pilot encountered nuisance air traffic which continued to encroach on his IFR flight plan course. The traffic in question was not talking to any ATC facility.

Narrative: I was on an IFR flight plan enroute to Jackson; TN (MKL) at 6000 MSL. Although most of the route was VMC; I was dealing with a stiff headwind and occasional light turbulence.The aircraft appeared to be maneuvering about 5 NM southwest of my position; at altitudes varying from about 500 feet above to about 500 feet below my assigned altitude. Memphis Center confirmed the other aircraft's position; but was not in contact with the other crew.Based on the other aircraft's speed and maneuverability; I had the impression that it was a light jet (perhaps a small Citation); but we never got close enough to confirm that identification.At about XA18Z; the other aircraft changed course towards my position; and Center approved a deviation to the right of about 20deg. After about 90 seconds; Center cleared me direct to MKL. I believe it was about this point that I was handed off to another Memphis Center controller.At approximately XA21Z; the other aircraft once more changed course towards my position. With Center's approval; I deviated to the right for about two minutes before being cleared direct to MKL.At about XA30Z; the other aircraft again headed towards my position and Center approved a deviation to the right. After about four minutes; Center cleared me direct to MKL and told me to descend to 4000 feet. At approximately XA45Z; what I believe was the same aircraft again headed toward me; but this time (if I remember correctly) it appeared he was about at my altitude and at my 6 o'clock position. When he got within about two miles; I attempted to contact Center but the controller was busy talking to other aircraft. When my traffic advisory system indicated that the other aircraft was within about a mile of my position and closing rapidly; I took evasive action by turning about 60 degrees to the left of my course. As soon as the frequency opened up; I advised Memphis Center I had again changed heading to avoid the other aircraft. (In retrospect; I should have used the phrase 'evasive action' to emphasize how serious I considered the situation.) I also advised the controller that I was concerned that I would soon approach my minimum fuel level (if I remember correctly; inadvertently using the phrase 'critical fuel').The controller voiced no objection to my actions; assured me there would be no further delays and gave me a vector towards MKL. A few minutes later; he cleared me for the visual approach to Rwy 20 and handed me off to MKL Tower. The rest of the flight was uneventful. (Once on the ground at MKL; I asked and Tower said he had not been in contact with the other traffic.)I can't recall having to deviate so many times for another aircraft. As they weren't talking to Memphis Center; I can only speculate why the other crew maneuvered as they did. In any event; under the circumstances; I felt I had no alternative but to take evasive action.

Data retrieved from NASA's ASRS site 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.