CAPT OF A LEARJET; LR31; ENTERED CLASS B AIRSPACE WHEN CLBING OUT ON IFR CLRNC FROM AN ARPT 10 MI FROM THE AIRSPACE BOUNDARY.

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I'M NOT SURE HOW WE 'VIOLATED DULLES AIRSPACE' IF ON THE GND AT FDK WE WERE TOLD OUR CLRNC WAS CLRED INTO CTLED AIRSPACE THEN DIRECT WESTMINSTER (CLB AND MAINTAIN 40...). I ASKED THE PNF TO QUERY THE CTLR ONE MORE TIME TO VERIFY WE WERE READING BACK THE CLRNC CORRECTLY; HE STATED 'CORRECT.' COULD HE POSSIBLY HAVE NOT HEARD US CLRLY? DEPARTED FDK APPROX XA05Z OFF RWY 23. CLBED TO 400 FT AGL BEFORE MAKING L TURN FOR WESTMINSTER (EMI). OUR CLRNC WAS CLRED INTO CTLED AIRSPACE; THEN DIRECT WESTMINSTER. (THE PNF; FO; VERIFIED ON THE GND THE CLRNC STATED ABOVE WHILE HOLDING IN POS. THE CTLR VERIFIED READBACK CORRECT.) AS WE WERE IN THE L TURN; ABOUT 20 DEG BANK; THE SUPVR CALLED US AND ASKED 'WHAT IS CTLED AIRSPACE TO YOU?' THE PNF REPLIED 'SIR I DO NOT UNDERSTAND YOUR QUESTION.' HE THEN STATED 'IT USUALLY DOESN'T TAKE A LEARJET 5 MI TO MAKE A TURNOUT; YOU JUST VIOLATED DULLES AIRSPACE.' WE STATED OUR APOLOGY BEFORE BEING HANDED OFF. MY CLBOUT WAS NORMAL (8-9 DEG PITCH) FOR PAX IN THE BACK AS WELL AS 15-20 DEG BANK; AND ONLY AFTER ACCELERATING THROUGH 400 FT AGL. I FELT THIS IS SAFEST WAY MANEUVERING ACFT (TRANSITIONING).