As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAINS SLIDING WINDOW OPENED ON ROTATION OUT OF JFK. CREW UNABLE TO CLOSE WINDOW IN FLIGHT. DUMPED FUEL AND RETURNED SAFELY TO JFK. REPLACED CAPTAINS SLIDING WINDOW AND LOWER TRACK, WINDOW OPERATES NORMALLY. IT COULD NOT BE DETERMINED IF WINDOW WAS LOCKED PRIOR TO TAKEOFF.