Incident Overview
On October 18, 2016, at 15:21 UTC, an Embraer ERJ-175 operated by LOT Polish Airlines departed from Runway 15 at Warsaw Chopin Airport (EPWA). Shortly after takeoff, the captain reported a technical problem with the slats, detected during their retraction. The crew attempted two resets of the system, both unsuccessful. Following the procedure for "SLAT FAILURE" as per the Quick Reference Handbook (QRH), the crew decided to return to the departure airport.
Response and Landing
The airport declared an uncertainty state in response to the situation. The aircraft landed without further incident at 15:32 UTC in a configuration with flaps set to 5 and slats set to 3. The uncertainty state was canceled at 15:33 UTC. After landing, the captain submitted a detailed report to the operator's Flight Safety Committee (KBZL).
Investigation Findings
Examination of the Flight Data Recorder (FDR) revealed no exceedances of flight parameters. Maintenance personnel identified a malfunction of the slat skew (twist) sensor as the cause of the problem. The faulty components were replaced. The operator's safety investigation concluded that the event resulted from normal operational wear and that the crew's decision to return was optimal. No violations of regulations were found, and no safety recommendations were issued.
Cause
The incident was caused by a malfunction of the slat skew sensor.