In respect of the FD Bars, they do appear to have been available when 2 ADRs (also 2 IRs) agreed within 20 KTS.
@MM43:
When ALT2'something' latches as a result of multiple 'ADR disagree', I can count down 1 knot at a time and when the difference between the 'median' ADR and the next closest reaches 19 knots, the FD's return and the AP 1+2 inop status is removed, regardless of the magnitude of the remaining ADR discrepancy. The A/P pb can then be engaged, even though ACTUAL speed (CAS) is below ACTUAL VLS. VLS is neither displayed nor indicated on the FMGEC landing phase PERF page. It is dashed and appears not to be computed.
As soon as I take the speed discrepancy back to 20 knots or above, the FD's go away and the A/P pb cannot be engaged.
Either I'm not really in ALT2B, which, on the surface, is problematic to determine, or there is a potential Level D problem, always a possibility, or 20 IS the magic number.
This is what I'm trying to determine.
