What was found
DURING TAXI OUT, BOTH ATC SHOWED ATC FAIL LIGHT AND EICAS ATC FAULT MSG ALSO LOWER ANTENNA FAULT ON RADAR DISPLAY. REPLACED COCKPIT CONTROL PANEL AND LOWER ANTENNA PER MM BOTH TRANSPONDERS NOW TEST NORMALLY.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
DURING TAXI OUT, BOTH ATC SHOWED ATC FAIL LIGHT AND EICAS ATC FAULT MSG ALSO LOWER ANTENNA FAULT ON RADAR DISPLAY. REPLACED COCKPIT CONTROL PANEL AND LOWER ANTENNA PER MM BOTH TRANSPONDERS NOW TEST NORMALLY.