BAE 146 CAPT MISTAKENLY FLEW A VISUAL DEP AFTER TKOF INSTEAD OF PUBLISHED SID DUE TO BELIEVING THAT THE FO HAD FILED A VISUAL DEP AS PER PREFLT PLANNING.

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PRIOR TO STARTING ENGINES I REQUESTED THE FO TO ASK GND CTL FOR A COMPANY APPROVED VISUAL DEP RATHER THAN THE FILED CLRNC (AN FMS DEP PROC). WE COMPLETED OUR CHKLIST (BEFORE START); AND ANTICIPATED RECEIVING A START SIGNAL FROM OUR GND PERSONNEL. WE WERE SURPRISED THAT OUR REQUEST TO START ENGINES WAS DENIED; AND THEN ADVISED THAT WE WOULD BE DELAYED BECAUSE THERE WAS A PROB WITH A 'POSITIVE BAG MATCH.' WHICH CONSTITUTED A SECURITY PROB. THIS DISTRACTION TO NORMAL PROCS INTERRUPTED THE TASK AT HAND; SO THAT BY THE TIME THE BAGGAGE PROB WAS RECTIFIED; WE WERE HURRYING TO GET OUR JOB DONE. THE FO HAD PREVIOUSLY REQUESTED OUR IFR CLRNC; BUT FAILED TO CHANGE THE DP. WE WERE ISSUED AN IFR CLRNC 'AS FILED' WHICH I DID NOT HEAR; AND I ALSO FAILED TO VERIFY WITH THE FO THE REQUEST FOR THE APPROVED VISUAL DEP. I DISCUSSED THE DEP AS 'STANDARD PROC' WITH THE FO AS WE WERE CLRED FOR TAKEOFF; BUT WAS THINKING THAT AS A 'STANDARD PROC' WE UTILIZE THE APPROVED VISUAL DEP AS AN EFFICIENT ALTERNATIVE TO THE PUBLISHED DEP PROC (DP). I WILL BE TOTALLY SPECIFIC BY NAME OF PROC IN THE FUTURE. WE WERE SHOCKED WHEN THE DEP CTLR INTERRUPTED THE QUIET AIRWAVES OF THE MORNING WITH AN INQUISITIVE REQUEST FOR WHICH DEP PROC WE WERE EXECUTING. I APOLOGIZED; AND ASKED IF THERE WAS ANY TFC SAFETY CONFLICT; AND THEY REPLIED; 'NEGATIVE.'