As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB-OUT, THE CREW NOTICED A STRONG BURNING SMELL IN THE COCKPIT. TURNED OFF R2 AND 3 WINDOW HEAT AND THE SMELL DISSIPATED. PULLED CB'S FOR L2-R3 AND L3-R2 WINDOW HEAT. AFTER APPROXIMATELY 3 MORE HOURS THE ODOR RETURNED. THIS TIME SMOKE CAME FROM LOWER LEFT CORNER OF L1 WINDOW. SCORCHING OBSERVED ON GLASS. SWITCHED OFF AND CB PULLED. A/C DIVERTED TO DXB. (M)