What happened
During a climb phase of flight, the aircraft reached flight level 280 when the flight crew noticed an unusual odor accompanied by smoke entering both the cockpit and the cabin. The captain made the decision to return to the departure airport immediately. The aircraft landed safely without any further complications or incidents.
The investigation
Following the landing, maintenance personnel conducted a thorough inspection of the aircraft. They identified issues within the air conditioning system. Specifically, several temperature sensors were found to be faulty and were replaced. Additionally, the recirculating fan assembly was removed and replaced with a new unit.
Findings
The replacement of the damaged temperature sensors and the recirculating fan assembly resolved the issue. After these repairs were completed, the aircraft was cleared for return to service. The source does not provide specific details regarding the aircraft registration or exact airport location.