As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 4020 - DURING DESCENT INTO ATL, SMOKE OCCURRED IN THE CABIN AND COCKPIT. THE CREW COMPLIED WITH THE QRH AND THE SMOKE DISSIPATED. THE AIRCRAFT LANDED SAFELY IN ATL. MAINTENANCE FOUND THE LEFT PACK RAM AIR CHECK VALVE STICKING AND FREED THE FLAPPER. OPERATIONAL CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)