As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF FROM MCO, CREW REPORTED THE AIRCRAFT THINKS IT'S ON THE GROUND - VNAV-LNAV-TCAS-A/T-ACARS WILL NOT WORK IN ANY FLIGHT MODES. CREW DECLARED AN EMERGENCY AND RETURNED TO FIELD AT MCO WITHOUT INCIDENT. MAINTENANCE CONFIRMED FAULT AND FOUND GROUND SENSING PROXIMITY SWITCH S105 OUT OF TOLERANCE. REPLACED SWITCH AND ADJUSTED PER AMM 32-09-01-825-002. OPS CHECKS NORMAL. NO FAULTS NOTED AT THIS TIME. PERFORMED SATISFACTORY TEST FLIGHT.