B737NG Autoland Fail Operation and Fail Passive

[Danial9874]

Fail operation system can continue autoland even with one autopilot failure

But B737 only have 2 autopilot available - A/P A and A/P B
how is it consider as fail operation if one A/P failed ?

Thank you guys, your input will be highly appreciated

[safetypee]

Is this particular version of the 737 fitted with HUD ?
if so how many ?
What is the architecture of each autopilot; dual monitored, or dual - dual ?

[EXDAC]

Originally Posted by Danial9874

Fail operation system can continue autoland even with one autopilot failure

But B737 only have 2 autopilot available - A/P A and A/P B
how is it consider as fail operation if one A/P failed ?

Thank you guys, your input will be highly appreciated

I don't know the 737 flight control systems but the answer will be in AC 120-28 - https://www.faa.gov/documentLibrary/.../AC120-28D.pdf

Edit to add - The fact that, below alert height, a IIIb autoland approach can continue with a system failure does not mean that the autoland system is "fail operational" with that system failure.