As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 538 - EN ROUTE LAS-ORD, WHEN WINDSHIELD ANTI-FOG TURNED ON DETECTED A BURNING SMELL. TURNED OFF WINDSHIELD ANTI-FOG. LANDED ORD WITHOUT FURTHER INCIDENT. OPERATED ANTI-FOG APPROXIATELY THREE HOURS. NO SMOKE OR ODOR NOTED. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)