SMT PLT INADVERTENTLY CROSSES ADIZ WITHOUT A FLT PLAN DUE TO THE DIFFICULTY IN FILING WHEN AIRBORNE AND THE INCONVENIENCE OF FILE PRIOR TO DEP RESULTING IN A MIL ESCORT TO LNDG ON US SOIL.

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VFR FLT FROM ZZZ ARPT TO ZZZ1 ARPT. I INQUIRED CUSTOMS OFFICIALS WHERE TO FILE A FLT PLAN. THEY SAID MOST PLTS WOULD DEPART AND FILE WITH ZZZ2 RADIO. I COULD NOT MAKE PAY PHONE AT TERMINAL WORK. FBO LOCATION REMOTE AND DID NOT APPEAR TO HAVE AN OFFICE. I TOOK THE LOCAL ADVICE AND DEPARTED VFR. AFTER DEP; ATTEMPTED TO CONTACT ZZZ2 RADIO ON FREQ -- NO ANSWER. CONTACTED ZZZ3 RADIO ON FREQ. THEY SAID 'EXTREMELY BUSY; STANDBY.' SOON THERE AFTER; ZZZ3 RADIO STARTED GIVING OUT NUMBERS (ACFT X STANDBY; YOU'RE NO 8). I SWITCHED BACK TO ZZZ2 APCH FREQ; THEY ANSWERED AND ASKED MY ALTITUDE 10500 FT SAID I WAS ABOVE THEIR AIRSPACE; CONTACT ZZZ5 CTR FREQ. I CALLED ZZZ5 CTR SEVERAL TIMES; COULD HEAR HIM TALKING TO OTHER ACFT; BUT WOULD NOT REPLY. CALLED ZZZ3 RADIO AGAIN AND ASKED FOR A NUMBER; SAID I WAS '#4; STANDBY.' A FEW MINS LATER HE GOT TO ME. I REQUESTED HE GIVE COMMERCIAL SERVICE MY ARR ZZZ4 ARPT XA40. HE SAID HE WOULD CALL 'BECAUSE I HAD A TO WAIT.' I DID NOT TRY TO AIR FILE A FLT PLAN. CONTINUED VFR TO ZZ4 ARPT SQUAWKING 1200. CONTACTED ZZZ4 TWR 10 MI SE DSNDING THROUGH 2000 FT. HE SAID RPT MIDFIELD R DOWNWIND. APPROX 5 MI SE OF ARPT INTERCEPTED BY 4 F16'S; ONE WITH GEAR DOWN. ZZZ4 ASKED IF I HAD F16'S IN SIGHT AFFIRMATIVE. TWR THEN CLRED ME TO LAND. I PERCEIVED AIRFILING WOULD BE EASY. I HAVE DONE SO BEFORE IN CONTINENTAL US SEVERAL TIMES. I SHOULD HAVE FILED A FLT PLAN FROM MY HOTEL WITH RELIABLE PHONE SVC AND I SHOULD HAVE LANDED AND FILED A FLT PLAN IN ZZZ2. DECIDING TO CONTINUE VFR TO MY ORIGINAL DEST ACROSS THE ADIZ WITH INCORRECT. I SHOULD HAVE KNOWN WEEKEND TFC WOULD BE HEAVY. CROSSED ADIZ WITHOUT A FLT PLAN.