RWY INCURSION. UNAUTH RWY ENTRY OP XING.

Narrative

WE WERE BEGINNING OUR LAST LEG OF A 7 1/2 HR BLOCK DAY. WE WERE GOING TO STEWART INTL; THE COMPANY'S MAINT BASE; TO DROP OFF THE PLANE. THE PLANE DIDN'T HAVE ANY PAX BECAUSE WE WERE GOING TO THE MAINT BASE. THE PLANE WAS FACING N AT THE BASE OF THE CTL TWR. I CALLED FOR THE TAXI CLRNC AND WAS INSTRUCTED TO TAXI TO RWY 35 VIA TXWY B TO TXWY A. BOTH THE CAPT AND I HEARD THE TAXI CLRNC AND WE WERE BOTH OPEN TO THE ARPT DIAGRAM IN OUR MANUAL. AS WE PULLED OUT; THE CAPT CALLED FOR THE BEFORE TKOF CHKLIST. I BEGAN THROUGH THE TKOF CHKS UNTIL GND CALLED US INQUIRING ABOUT OUR POS ON RWY 35 AT TXWY B. INSTEAD OF MAKING A R TURN ON TXWY A; WE PROCEEDED TO CROSS RWY 35. FORTUNATELY NO ONE WAS TAKING OFF OR LNDG ON RWY 35. BOTH OF US HEARD AND UNDERSTOOD THE CLRNC. AS FAR AS MY ROLE GOES; DELAYING THE BEFORE TKOF CHKLIST UNTIL WE WERE CLOSER TO THE END OF THE RWY WOULD HAVE BEEN BETTER. 2 EYES ON THE TAXI RTE ARE ALWAYS BETTER THAN ONE. BECAUSE IT WAS THE LAST FLT OF THE DAY; WE WERE EMPTY; AND WE HAD BEEN FLYING TOGETHER ALL MONTH LED TO COMPLACENCY AND A LET-DOWN OF OUR WATCH OVER EACH OTHER. SUPPLEMENTAL INFO FROM ACN 252477: WHILE ATTEMPTING TO COMPLETE THE BEFORE TKOF CHKLIST; I MISREAD THE TAXI DIAGRAM; AND INADVERTENTLY CROSSED RWY 35 WITHOUT A CLRNC. FORTUNATELY; I HAD VISUALLY CHKED FOR TFC; AND NO CONFLICT RESULTED. I ALSO THINK THAT I GOT COMPLACENT BECAUSE MHT IS A 'SMALL' ARPT. AT LARGE ARPTS; I ALWAYS HAVE THE TAXI DIAGRAM CLIPPED TO MY YOKE; AND PAY CLOSE ATTN TO TAXIING. I AM GOING TO START DOING THIS AT ALL ARPTS NOW.