AFTER CPR JET PIC TURNS OFF THE TAXI LIGHTS DURING A NIGHT TAXI OP; THE FO TAXIES THEIR FLT ONTO ACTIVE RWY 18. ACR JET ON FINAL TOLD TO GO AROUND BY TWR AT FNT.

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AT THE FNT ARPT; I WAS PERFORMING THE DUTIES OF PF OF A LEAR 35. AS FO; I WAS SEATED IN THE R SEAT DURING A NIGHT OP IN VFR CONDITIONS. THE CAPT CONTACTED GND CTL AND OUR ACFT WAS CLRED TO TAXI TO RWY 18 VIA TXWY C AND WAS INSTRUCTED TO HOLD SHORT OF THE INTXN OF RWY 18. AS WE APCHED THE INTXN OF RWY 18; THE CAPT (WHO WAS INVOLVED ONLY IN READING THE TAXI CHKLIST) TURNED OFF THE ACFT TAXI LIGHTS. THIS PREVENTED ME FROM SEEING THE PAINTED RWY MARKINGS AND RWY/TXWY SIGN WHICH WAS POSTED TO THE L SIDE OF THE ACFT. AS I CONTINUED TO TAXI IN DARKNESS AND RECOGNIZED THE PAINTED RWY MARKINGS AND RWY LIGHTS; I REALIZED THAT I HAD TAXIED ONTO THE RWY. I IMMEDIATELY PERFORMED A 180 DEG TURN TO THE L AND EXITED THE RWY BACK ONTO THE TXWY. THE TWR ORDERED A B727 ON A 3 MI FINAL TO THAT RWY TO GO AROUND. THIS WAS A FAILURE OF CRM. I WAS NOT FAMILIAR WITH THIS ARPT OR THE RWY AND TXWY CONFIGN. IN RETROSPECT; I SHOULD HAVE REQUESTED THAT THE CAPT NOT TURN OFF THE TAXI LIGHTS AND READ THE ARPT DIAGRAM AND FOLLOW ALONG OUR PROGRESS TO THE RWY. I AM CURRENT AND QUALIFIED TO SERVE AS PIC OF THIS ACFT. IF I HAD BEEN ALLOWED TO SIT IN THE L SEAT WHILE PERFORMING THE PF DUTIES; THIS EVENT WOULD NOT HAVE OCCURRED BECAUSE I COULD HAVE EASILY OBSERVED THE RWY SIGN POSTED ON THE L AND WOULD HAVE HAD CTL OF THE ACFT TAXI LIGHTS.