Narrative:

IFR southbound to lal via lake parker cancelled IFR about 8 miles out at maybe 5;000 ft. During descent deviated east about a mile to hit lake parker steam plant on a westward heading. [I] directed passenger in right seat to assist in watching for traffic. Suddenly a warbird A4 or L39 type jet passed to the right side at an extremely high rate of speed at the same altitude; perhaps 100 ft or less in distance. Paint scheme appeared to be navy grey with navy like numbers. Rate of passage was way too fast to take evasive maneuvers or to see other identifying information.ways to prevent it:maintain IFR all the way to the field. Have ATC provide traffic advisories prior to cancellation. Jet traffic obey NOTAM to stay away from lal. (I assume the traffic was departing lal.)turbine traffic departed IFR.better traffic vigilance from both cockpits. Leave transponders on during lal departure/arrival. (I was enough shook up that I failed to complete the task of setting 1200 and turning the transponder to standby; hence my transponder was active at the time of the incident).

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Original NASA ASRS Text

Title: A CE340 pilot inbound to LAL for an air show suffered an NMAC with an unidentified turbine powered aircraft apparently departing from LAL.

Narrative: IFR southbound to LAL via Lake Parker cancelled IFR about 8 miles out at maybe 5;000 FT. During descent deviated east about a mile to hit Lake Parker steam plant on a westward heading. [I] directed passenger in right seat to assist in watching for traffic. Suddenly a warbird A4 or L39 type jet passed to the right side at an extremely high rate of speed at the same altitude; perhaps 100 FT or less in distance. Paint scheme appeared to be navy grey with navy like numbers. Rate of passage was way too fast to take evasive maneuvers or to see other identifying information.Ways to prevent it:Maintain IFR all the way to the field. Have ATC provide traffic advisories prior to cancellation. Jet traffic obey NOTAM to stay away from LAL. (I assume the traffic was departing LAL.)Turbine traffic departed IFR.Better traffic vigilance from both cockpits. Leave transponders on during LAL departure/arrival. (I was enough shook up that I failed to complete the task of setting 1200 and turning the transponder to standby; hence my transponder was active at the time of the incident).

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.