Narrative:

First officer failed to check or improperly checked left side sliding window for 'closed and locked.' window had about a 2 inch gap at the rear edge. On takeoff the cockpit noise level rose to an unusually high level when takeoff power was applied. I thought it was an aircraft pack valve run away -- no problem! At 90-100 KTS the noise was very unusually loud. Further analysis made me realize the window was not 'closed and locked.' aborted at 120 KTS. Uneventful stop. Limited check of the window is to unlatch the lock and crank closed. If the handle does not move toward closed, the check is complete. I think a better check would be to check 'roller forward, handle latched' as on the widebody transport. Visually checking the lower arm in the over center (therefore locked) position would be a more positive and safer check.

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Original NASA ASRS Text

Title: FLC OF AN LGT ACR ACFT ABORTED TKOF DUE TO AN UNLATCHED COCKPIT WINDOW.

Narrative: FO FAILED TO CHK OR IMPROPERLY CHKED L SIDE SLIDING WINDOW FOR 'CLOSED AND LOCKED.' WINDOW HAD ABOUT A 2 INCH GAP AT THE REAR EDGE. ON TKOF THE COCKPIT NOISE LEVEL ROSE TO AN UNUSUALLY HIGH LEVEL WHEN TKOF PWR WAS APPLIED. I THOUGHT IT WAS AN ACFT PACK VALVE RUN AWAY -- NO PROB! AT 90-100 KTS THE NOISE WAS VERY UNUSUALLY LOUD. FURTHER ANALYSIS MADE ME REALIZE THE WINDOW WAS NOT 'CLOSED AND LOCKED.' ABORTED AT 120 KTS. UNEVENTFUL STOP. LIMITED CHK OF THE WINDOW IS TO UNLATCH THE LOCK AND CRANK CLOSED. IF THE HANDLE DOES NOT MOVE TOWARD CLOSED, THE CHK IS COMPLETE. I THINK A BETTER CHK WOULD BE TO CHK 'ROLLER FORWARD, HANDLE LATCHED' AS ON THE WDB. VISUALLY CHKING THE LOWER ARM IN THE OVER CTR (THEREFORE LOCKED) POS WOULD BE A MORE POSITIVE AND SAFER CHK.

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.