dimitris lam Again yes, the RA didn't 'fail' which clearly, again is part of the problem, no?
In a correctly designed system the A/T would command RETARD reaching 27' RA and only 27' RA, not -8' RA not 1,500' or 0' or any of the other possible RA indications available. Once triggered the A/T should then stay in RETARD until the A/T disconnects 2 secs after receiving the WOW signal. If the RA doesn't see 27' then it shouldn't command RETARD, because landing without RETARD in the flare is a whole lot safer than having the A/T deciding without input from the crew to go into RETARD at 2000'.
HarryMann Yes, a one way check valve. IF (x=27', RETARD, otherwise don't)