A319 CREW ENCOUNTERED AN APCH CTLR WITH SUCH A HVY FOREIGN LANGUAGE ACCENT THAT THEY WERE UNABLE TO UNDERSTAND HIM. THE ACFT MAY HAVE PENETRATED PROHIBITED AIRSPACE AS A RESULT.

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WHILE ON IRONS 4 ARR TO DCA; THE CAPT AND I NOTICED ATC CTLR HAD A VERY HVY ACCENT WHICH MADE HIM DIFFICULT TO UNDERSTAND. ALSO; IT SOUNDED AS IF HE WAS OVERLY BUSY AND POSSIBLY PREOCCUPIED WITH AN ACR Y FLT AHEAD OF US. UPON XING THE DCA VOR; I ASKED THE CAPT TO CHK WITH THE CTLR AS TO WHEN HE WANTED US TO START OUR L TURN. THE CAPT TRIED 2; POSSIBLY 3 TIMES WITH EXTREME DETERMINATION TO GET A L TURN. THE CTLR'S RESPONSES WERE UNINTELLIGIBLE DUE TO HIS HVY ACCENT. THE CTLR FINALLY COMMUNICATED 'TURN L 230 DEGS.' I DID SO AT ONCE! THE REST OF THE FLT WENT AS NORMAL; COMPLETED WITH AN LDA DME RWY 19 APCH. THE LNDG WAS NORMAL AND WE TAXIED I WITH NO UNUSUAL COMMENTS FROM ATC. ON MAR/SUN/02; THE CAPT CALLED ME AT HOME AND ADVISED ATC ALLEGED WE PENETRATED P56. I DID NOT BELIEVE WE DID SO. HOWEVER; I HAVE NO WAY OF DETERMINING EXACTLY WHERE P56 IS. IT IS NOT DEPICTED ON MY NAV DISPLAY AND IT WAS DARK AND I AM NOT TOTALLY FAMILIAR WITH THE DCA AREA! IN THE FUTURE; THIS PROB CAN BE SOLVED BY ADDING A HDG TO THE IRONS 4 ARR AFTER PASSING THE DCA VOR! SUPPLEMENTAL INFO FROM ACN 540451: WE WERE APCHING DCA FROM THE S ON THE IRONS 4 ARR. WX WAS CLR. WE WERE CLRED DIRECT DCA VOR. DCA WAS UTILIZING LOC 19 APCHS. WE WERE ANTICIPATING A TURN TO THE W FOR VECTOR TO THE FINAL APCH COURSE. THE ATC CTLR SPOKE WITH A HVY ACCENT. AN INSTRUCTION WAS ISSUED TO MAKE A TURN TO HDG 270 DEGS; HOWEVER; THE CALL SIGN WAS UNINTELLIGIBLE. WE ASKED THE CTLR 3 TIMES TO CONFIRM THE VECTOR WAS FOR US. WE WERE WITHIN 2 MI OF DCA VOR AT 10000 FT WITH A SIGNIFICANT TAILWIND. IN OUR TURN ON THE VECTOR; ATC ALLEGES WE PENETRATED PROHIBITED AIRSPACE P56. WE AT NO TIME KNOWINGLY TRANSGRESSED P56. CONTRIBUTING FACTORS: 1) CTLR NONSTANDARD USE OF ENGLISH LANGUAGE; OR SPEECH IMPEDIMENT. 2) ATC CTLR LATE IN ISSUING VECTOR INSTRUCTIONS. 3) HIGH GND SPD DUE TO TAS/TAILWIND THAT MADE WIDE GND TRACK ON VECTOR.