A/p 737

[it.pilot737]

Why in case of single IRS ops the use of autopilot is not raccommanded?

[InSoMnIaC]

I think it has something to do with the fact that each Autopilot gets Pitch and Roll data from Both IRS's. If 1 IRS is U/S with the Attitute transfer switch in Normal then 1 of the signals will be errornous. If you Select the Attitude Transfer switch in the position "Both on L" or "both on R" (depending on which IRS is at fault) then The autopilot will function however it will only get Attitude data from 1 IRS ie there is no redunduncy in case of a problem with the other IRS.

[Ka8 Flyer]

I think it has more got to do with the fact that both primary flight instruments "see" the same data the engaged AP does so you can't cross check its operation (unless you look at the stby ADI) if you're in the soup.

[InSoMnIaC]

So the only way to cross check its operation is via the standby instruments... what is the difference then when you hand fly. how can you cross check the instruments then.. I suspect it's also via the standby instruments. so u see it makes no difference if you fly or the A/P flys. The cross check issue is still the same.

What i said was that the Autopilot itself can't cross check it's progress because it only has 1 set of input data.