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Do modern commercial airliners have manual control capability to fly and land if electric power remains on but all computer systems and digital communication/guidance fails?

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  • $\begingroup$ Your question is really generic. You can restrict it to some aircrafts types as some modern airliners (e.g. the A380) rely on electronic systems only whereas other (e.g. A320 with rudder and trim) not. (I really have no idea for Embraer or ATR airliners) $\endgroup$
    – Manu H
    Jun 16, 2019 at 10:31

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For a non-fly-by-wire airliner, yes. It's just another airplane in the end and as long as there is hydraulic power you can fly it. If the weather is clear you don't need any electronic aids at all, if you know how to fly in the first place.

For FBW, where computers control the controls and the pilot is just telling the computers what he wants to do, they are dependent on multiple levels of electronic redundancy to account for those sorts of breakdowns.

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John K answer is a great summary, just to complement you should consider the probabilistic safety of systems.

In a conventional airliner you depend on the hydraulic system, on cables, on mechanical transmission etc

On FBW (flight by wire) you depend on electrical power, electrical and/or hydraulic servo controls, on multiple AND/OR data communication buses, on multiple AND/OR computers...

On FBW you have a high level of redundancy which allows for multiple way of implementations such as:

  • On the same surface ( aileron, elevator etc), you have several servo controls some of them are autonomous requiring only the electrical generation and the command from the computers, and some other dependable of the central hydraulic system and of the computer command

  • several computers may command every servo control

  • multiple parallel data communication such as ARINC 429 and ARINC 629 and fiber optic etc

  • In addition to the conventional multiple layer of electrical generation you have Multiple emergency power such as central batteries, and local batteries for the FBW

Considering the safety of modern airliners for instance the B777 which is nearly a full FBW aircraft, it had no accident.

What makes the superiority of FBW airliners is the redundancy of equipment and the redundancy of implementation.

The weakness of conventional airliners is the lack of redundancy, considering for example a dépressurisation that deforms the deck and prevents the mechanical cable transmission to the elevators servo control, we get into a hopeless situation, while with FBW you will just do a standard emergency descent.

In the question, the assumption of loosing all communication between computers while electrical power remains is probabilistically impossible.

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