As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDED ORD UNDER AMBER ALERT DUE TO L/E SLAT ASYMMETRY. *S/D* FAILURE OF ONE OF THE TWO INBOARD SLAT LOSS INDICATION SWITCHES CAUSED THE SYSTEM SHUTDOWN. REPLACED THE BAD SWITCH AND RETURNED AIRCRAFT TO SERVICE WITHOUR FURTHER INCIDENT. THIS IS A KNOWN INDUSTRY PROBLEM WITH THE 757 AIRCRAFT. UNITED IS CORRECTING THE PROBLEM DURING HEAVY MAINTENANCE VISITS.