AF 447 Thread No. 9

[A33Zab]

@OK465:

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.

AMM 22-11-00 PB 001 AUTOPILOT/FLIGHT DIRECTOR (AP/FD) ENGAGEMENT D/O.

Par. 2.C:

(2) AP engagement inhibition and disengagement logics
(a) Pitch and roll angle limits
- Roll angle

• AP engagement is inhibited when abs(phi) > 40°
• AP is automatically disengaged when abs(phi) > 45°.

- Pitch angle

• AP engagement is inhibited when theta < -10° or theta > +22°
• AP is automatically disengaged when theta < -13° or theta > 25°.

(b) AP engagement is inhibited in flight when CAS < VLS or CAS > (VMO/MMO or VLE/VFE).

(c) AP engagement is inhibited when the FMGEC receives the "pitch angle protection active" information from the FCPC.