Date: 201907
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Military
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Second aircraft: Skyhawk 172/Cutlass 172
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor
Human factors: Distraction; Troubleshooting; Situational Awareness; Communication Breakdown
Second reporter function: Single Pilot
Anomaly: Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Took Evasive Action
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: I was taxiing from runway XXL via taxiway Y With a right turn (South) assigned onto taxiway Z. The engine started to run rough due to an over rich condition as I was approaching the turn on taxi way Z. I missed the turn as I was attempting to rectify the engine issue. I crossed the runway XX - YY hold short line. The aircraft I was operating is a tail wheel aircraft. I immediately turned the aircraft back around 360 degrees and exited the runway. As I was executing the turn around I observed a high wing Cessna holding short of the intersection of taxiway Y and taxi way Z on Y taxi way. I was at a full stop at this time on the safe side of the hold short line. the Cessna seeing me turn back around and now pointed toward his aircraft immediately added power; entered the intersection and turned to his North toward runway YYL. After he was clear I entered the intersection and turned South. No radio calls where made during this event.


Second narrative: I landed on XXR.  Aircraft X had just landed on XXL.  Aircraft X was instructed to turn left on taxi X and go to ground.  I was instructed by tower to turn left on taxi F cross XXL and follow behind Aircraft X on taxi Y hold short YY with tower. I followed behind Aircraft X and was cleared to cross YY; which was the active at that time.  Aircraft X crossed YY and started a left turn onto taxi D; at which time Aircraft X did a 180 degree turn and started coming back at my airplane on taxi Y.  Tower told me to stop.  I already had.  I could see Aircraft X pilots face so he could see me.  He kept coming at me; so I did a full power 90 degree left turn onto Taxi Z to get out of the way of his prop. I asked the tower what the heck was going on; and they said that Aircraft X had missed his turn and decided; uninstructed; to do the 180 turn.  Aircraft X knew I was behind him as I waited for him to pass us on Taxi B.  Aircraft X never stopped crossed YY and turned south on to Taxi Z to get to his hangar.  I never heard the ground instructions to Aircraft X; but he would never have been cleared to cross YY as the warbird hangar was on Taxi Z which does not require crossing YY.  So Aircraft X's pilot crossed the active YY without permission twice; and did a 180 without permission.Aircraft X pilot's visibility was not an issue.  I had eye contact with him the entire time of the event; and yet he chose not to stop what he was doing.  That is why I got out of the way.Solution to this problem is Aircraft X pilot needs lots of controlled class D training/testing.  There seems to be a cockiness expressed by many of the war bird drivers that the rules do not apply to them and that they are a very special group of pilots.  I say this as they do many flybys etc. with tower permission; so they are accustomed to getting their way.  I have had 2 close calls on IFR flight plans; both have been with WARBIRDS.In fact I had been cleared for a visual approach to YY by ATC before being handed off to tower. Tower had me change to XXR because Aircraft X was over the field doing a flyby before landing on XXL.The other issue was that Aircraft X was on ground and I was on tower; per the towers instructions.  I had no ability to listen nor speak with Aircraft X.This scared me and my wife to death.  That big propeller would have killed us; while the old Aircraft X driver taxied on unknowingly.


Synopsis: Two GA pilots reported their version of a ground conflict after one performed an uninstructed 180 turn on a taxiway.