As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 479 - MKE-CLT - ON CLIMB-OUT FROM MKE, CAPTAIN NOTICED AN AIR LEAK FROM THE CAPTAIN SIDE SLIDING WINDOW. ATTEMPTED TO CLOSE IT BUT WAS UNSUCCESSFUL. FLIGHT RETURNED TO MKE WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND UPPER AFT ROLLER WAS NOT ALIGNED INTO THE TRACK. REPOSITIONED THE ROLLER INTO THE TRACK. THE WINDOW OPERATED NORMALLY. (M)