AN ACR LGT ABORTED ITS TKOF WHEN THE CAPT'S SLIDING WINDOW CAME OPEN.

Narrative

AFTER PUSHBACK FROM THE GATE; NEW PAPERWORK WAS DELIVERED TO THE ACFT THROUGH THE CAPT'S SIDE WINDOW. THE WINDOW WAS CLOSED AND THE AFTER START; TAXI; AND BEFORE TKOF CHKLISTS WERE DONE NORMALLY. ON TKOF ROLL; AT ABOUT 80 KTS; THE CAPT'S WINDOW SLID OPEN. AN ATTEMPT TO CLOSE IT WAS UNSUCCESSFUL SO WE ABORTED THE TKOF AT ABOUT 110 KTS. THE ACFT WAS STOPPED WITH NO PROBS ON THE RWY AND AFTER TAXIING CLR; THE WINDOW WAS SECURED. BECAUSE OF SOME UPSET PAX WE THEN ELECTED TO RETURN TO THE GATE BEFORE EVENTUALLY PROCEEDING WITH THE FLT. 2 THINGS WHICH CONTRIBUTED TO THIS: WINDOWS ARE CHKED ON BEFORE START CHKLIST WHICH IS DONE BEFORE PUSHBACK. SINCE THE WINDOW WAS OPENED AFTER THAT; THERE WAS NO CHK THAT IT WAS CLOSED AND LOCKED. THE CAPT WAS NEW TO THE LGT AND HAD ALSO JUST COME OFF SICK LEAVE. EARLIER HE HAD SHOWN SOME CONFUSION OVER HOW TO OPEN AND CLOSE THE WINDOW. I SHOULD HAVE PAID CLOSER ATTN TO MAKE SURE HE LOCKED THE WINDOW AFTER THE PAPERWORK ARRIVED. ANOTHER CONTRIBUTING FACTOR WAS THAT WE WERE RERTED; PLUS FLYING AN 'ALL-NIGHTER' THAT WAS NOT ON OUR ORIGINAL SCHEDULE SO NEITHER ONE OF US WAS AT OUR PEAK.