It doesn’t say RUDDER RATIO is an indication of unreliable airspeed. It says:
“Display of one or more of the following EICAS messages may be evidence of unreliable airspeed/Mach indication:
•AILERON LOCKOUT
•ALT DISAGREE
•CAPT PITOT
•F/O PITOT
•IAS DISAGREE
•L AUX PITOT
•OVERSPEED
•PROBE HEAT
•R AUX PITOT
•RUDDER RATIO”
Basically, faults that may corrupt the input to the ADCs such as PROBE HEAT or failure of systems that have an ADC input such as RUDDER RATIO, may be an indication or confirmation of unreliable airspeed.
Last edited by Beakor; 17th October 2022 at 16:47.
Reason: Typo