Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Returned To Gate; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft; Environment - Non Weather Related
Flt ABC; MIA-ZZZ. At Gate Both Captain & First Officer RA displayed fluctuations 10 to 2 at Gate and during push back. After engine start; RA both displayed -4; but TCAS FAILED was now displayed on both NAV displays and LNAV went active from white (armed) to active green with lateral course display on both PFD's. Aircraft taken out of service by Maintenance. ASAP Filed. Maintenance history on aircraft instruments. Needs to include all aircraft instrument malfunctions and issues with 5g interference/activation.
Air carrier Captain reported the aircraft was taken out of service after returning to the gate to address the failures of the radio altimeter and the TCAS system. Reporter cited 5G interference as a probable cause.