Narrative:

Flight arrived at csg at XA48 local (eastern). We were a through flight which originated at dhn, went to csg, then continued to mem. Tower was closed and first officer canceled our flight plan with center when we were on ground. We did a quick turn, while I did an engine start, first officer picked up our IFR clearance with tower which had just opened. I assumed first officer had gotten our IFR clearance with FSS or center and I started to taxi. I did not realize tower had opened until controller asked if we would be ready upon reaching the runway. Related factors: inbound ATIS reported tower did not open until XB00 am local (eastern). Flight deck clocks and crew watches set to central time. Dhn which is where flight originates is also on central time. Flight is a 2 leg return flight from a continuous duty overnight with less than 5 1/2 hours at the hotel. Therefore, crew was tired and not functioning at 100%. Crew communication was minimal (just checklist and company calls). I did realize first officer had talked to tower for IFR clearance.

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Original NASA ASRS Text

Title: FLC OF LTT UNAWARE THAT TWR HAD OPENED BEGINS TAXI WITHOUT CLRNC. THEY HAD LANDED PRIOR TO TWR OPENING.

Narrative: FLT ARRIVED AT CSG AT XA48 LCL (EASTERN). WE WERE A THROUGH FLT WHICH ORIGINATED AT DHN, WENT TO CSG, THEN CONTINUED TO MEM. TWR WAS CLOSED AND FO CANCELED OUR FLT PLAN WITH CTR WHEN WE WERE ON GND. WE DID A QUICK TURN, WHILE I DID AN ENG START, FO PICKED UP OUR IFR CLRNC WITH TWR WHICH HAD JUST OPENED. I ASSUMED FO HAD GOTTEN OUR IFR CLRNC WITH FSS OR CTR AND I STARTED TO TAXI. I DID NOT REALIZE TWR HAD OPENED UNTIL CTLR ASKED IF WE WOULD BE READY UPON REACHING THE RWY. RELATED FACTORS: INBOUND ATIS RPTED TWR DID NOT OPEN UNTIL XB00 AM LCL (EASTERN). FLT DECK CLOCKS AND CREW WATCHES SET TO CENTRAL TIME. DHN WHICH IS WHERE FLT ORIGINATES IS ALSO ON CENTRAL TIME. FLT IS A 2 LEG RETURN FLT FROM A CONTINUOUS DUTY OVERNIGHT WITH LESS THAN 5 1/2 HRS AT THE HOTEL. THEREFORE, CREW WAS TIRED AND NOT FUNCTIONING AT 100%. CREW COM WAS MINIMAL (JUST CHKLIST AND COMPANY CALLS). I DID REALIZE FO HAD TALKED TO TWR FOR IFR CLRNC.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.