FLC CABIN CREW LEFT ACFT PARKED ON RAMP WITH PAX ABOARD CONTRARY TO COMPANY PROCS.

Narrative

AS A REGIONAL AIRLINE; WE START AT A MAJOR HUB ARPT AND FLY TO SEVERAL SMALL ARPTS; DEPLANING A FEW PAX AT EACH STOP. AT THE THIRD STOP WE REVERSE THE RTE AND PICK UP PAX AT EACH OF THE PREVIOUS ARPTS AND TAKE THEM TO THE HUB. ON THIS DAY WE WERE RUNNING SEVERAL HRS LATE AND SO ENPLANED PAX AT THE OUTBOUND STOPS; INTENDING TO OVERFLY THESE ARPTS BACK INBOUND TO THE HUB. NORMALLY; DURING THE TURNAROUND AT THE FAR END OF THE RTE; THE CREW LEAVES THE ACFT TO PERFORM VARIOUS PREFLT ACTIVITIES. ON THIS DAY I WENT INTO THE TERMINAL BUILDING; THINKING THAT THE FLT ATTENDANT WAS IN THE ACFT WITH THE PAX. HOWEVER; WHEN I GOT INSIDE I SAW BOTH THE CAPT AND THE FLT ATTENDANT WERE INSIDE. THUS; I HAD LEFT APPROX 25 PAX ALONE IN THE ACFT. WITHOUT ANY CREW MEMBERS ON BOARD THERE WAS CONSIDERABLE RISK TO THE PAX IF ANY HAZARDOUS SIT SHOULD OCCUR; SUCH AS AN APU FIRE. THERE WERE 2 SPECIFIC HAZARDS: FIRST; A SIT COULD HAVE DEVELOPED THAT WOULD NOT BE RECOGNIZED AS HAZARDOUS BY THE PAX. SECOND; NO CREW MEMBERS WERE ON BOARD TO DIRECT EVAC OR OTHERWISE RESOLVE THE SIT. CONTRIBUTING FACTORS WERE: 1) MY LACK OF SITUATIONAL AWARENESS THAT THERE WERE NO OTHER CREW MEMBERS ON BOARD. 2) FORCE OF HABIT. WE ALWAYS DEPLANED AT THIS STOP TO PERFORM NECESSARY TASKS TO START THE RETURN TRIP. 3) SELF CREATED SENSE OF URGENCY TO GET THE FLT TURNED AROUND AS FAST AS POSSIBLE. 4) FATIGUE. WE HAD BEEN IN THE ACFT FOR 8 HRS WITHOUT ANY BREAKS EXCEPT FOR THE PREVIOUS TURNAROUND; WHICH WAS SPENT PERFORMING PREFLT ACTIVITIES.