54 votes
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Why do passenger jets accept input that will cause the aircraft to perform dangerous maneuvers it was not designed for?

Generally speaking, pilots don't like it when a computer interprets or limits their actions. They want final control. They don't always get their way on this but that's their preference. If I recall ...
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  • 536
34 votes
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How does the Airbus flight computer's voting system work?

As far as I read in various documents about A320 and remember them correctly: There are three systems handling different parts of the primary flight control: ELAC (elevator & aileron computer) ...
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34 votes
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Why aren't there simplified fly-by-wire helicopter controls?

Helicopter manufacturers seem to have been slow to adopt fly-by-wire systems. I used to work in the General Dynamics group which designed the fly-by-wire system for the F-16. That was the first ...
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34 votes
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Would a wireless fly by wire system be practical?

The fly-by-wire is absolutely vital for control of the aircraft, and the three dominating factors here are safety, safety and safety. Weight is not one of them. The fly-by-wire system is triple or ...
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  • 57.8k
25 votes
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What kind of delay does the A320's fly-by-wire system add?

Yes there will be a delay, but the delay caused by the control loop is really tiny. I've seen position control loops run successfully and stable at a couple of hundred Hz for simulator motion systems, ...
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25 votes
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What is the difference between autopilot and fly-by-wire system?

An autopilot can fly the aircraft based on pilot selected modes. The autopilot therefore reduces the pilot's workload by replacing manual inputs via the yoke or sidestick. A fly-by-wire (FBW) system ...
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  • 45k
22 votes

Why do passenger jets accept input that will cause the aircraft to perform dangerous maneuvers it was not designed for?

The philosophy is that the pilot knows best. If they need to make a maneuver, they should be trusted to do so. Although there are absolute limits such as structure, other limits are less exact and ...
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22 votes
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How are fly-by-wire airliners controlled in case of complete electrical failure?

For the complete electrical failure in the aircraft, the following systems have to fail: The onboard power generation system, usually a synchronous generator has to fail in all the engines. The APU (...
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  • 98.6k
22 votes

What is the maximal acceptable delay between pilot's input and flight control surface actuation?

Excessive phase lag is a direct contributor to Type I Pilot-Induced Oscillation (PIO). Phase lag comes from: Rigid body dynamics of the aircraft (e.g. delay between elevator surface and pitch rate ...
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18 votes

Why do passenger jets accept input that will cause the aircraft to perform dangerous maneuvers it was not designed for?

Let's just focus on roll. The same command that can be used to roll the aircraft from 0° roll angle to 30° can be used to roll it from 30° to 60°. Who is to decide at what roll angle the airplane is ...
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18 votes
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Do pilots use the pedals in flight on planes with a sidestick (Airbus)?

The rudder pedals are not usually used in flight, even with the autopilot off. The rudder on the Airbus A320 can be controlled via a mechanical connection to the rudder pedals in the flight deck, but ...
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  • 45k
17 votes

What is the difference between autopilot and fly-by-wire system?

Fly-by-wire system removes physical link between cockpit controls and flight control surfaces. To do this, there must be some sort of rule how pilot's input is interpreted and converted into control ...
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  • 2,805
16 votes

Why can't the A320's computer-imposed limits be overridden?

Computer limits can be overridden on an Airbus as a ‘last resort’, though I have serious doubts that would have helped with the landing on the Hudson incident. Granted, getting out of Normal Law is ...
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15 votes

Why do passenger jets accept input that will cause the aircraft to perform dangerous maneuvers it was not designed for?

Most new designs do not accept such inputs. That includes: Airbus models from A320 onwards (includes A318 and A319 that are variants of A320). Boeing models B777 and B787. Sukhoi SuperJet Su100. ...
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  • 54.1k
14 votes
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Can light GA aircraft implement fly-by-wire technology?

There are multiple factors here: The first and main one is of course weight. Fly-By-Wire requires computers and hydraulics to actuate the surfaces in a small plane weight is critical and a FBW system ...
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  • 96k
14 votes

Are NATO fly-by-wire fighters designed to feel like F-14 Tomcats?

Most decidedly not, at least not for the first fly-by-wire fighter in the NATO arsenal, the F-16. Its stick, in initial block versions, did not move at all, instead using piezoelectric load cells to ...
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  • 22.3k
13 votes

Would a wireless fly by wire system be practical?

That will be very unlikely simply because wireless is much less reliable by several order of magnitude. considering the current day an age of terror threats if the encryption (and you will need ...
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13 votes

Are there any fly-by-wire airliners with negative or near-neutral pitch stability?

No. Modern FBW airliners use less static stability than what the early jets were used to, but stability is still positive. The negative camber at the root airfoil of sweptback horizontal tails might ...
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13 votes

What kind of delay does the A320's fly-by-wire system add?

I don't have an answer for the timings (I personally don't think that's publicly available information), but I can answer this is the delay noticeable by pilots? as I have some direct experience, ...
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13 votes
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Why did fly-by-wire systems take so long to implement?

A simple answer is that the aircraft control system has ultimate responsibility for survival of the aircraft. If it completely fails, you are as good as dead in most cases. Short of in-flight ...
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  • 8,605
13 votes

Do pilots use the pedals in flight on planes with a sidestick (Airbus)?

Side stick or no, once airborne, you never touch the rudder pedals in any airliner when flying except during landing where independent rudder inputs are used to keep the airplane lined up during the ...
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  • 104k
13 votes
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Under what circumstances does the F-16 and possibly similar fighters deploy leading edge slats?

Technically, F-16 and "similar fighters" have leading edge flaps (LEF) (or droop flaps), rather than slats. The difference is that they don't form a gap between themselves and the main ...
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  • 8,605
12 votes
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Is the A380 ailerons' kinematic modified in alternate law?

Valse Des Ailerons (Waltz of Ailerons) or VDA is a nickname for the Load Alleviation Function (LAF) which is part of the flight control system. LAF uses all ailerons and spoiler 6 to 8 to alleviate ...
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  • 74.8k
12 votes
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Do Airbus pilots have to practice flying in alternate law?

It appears in both situations that the PF had trouble stabilizing the aircraft roll attitude. Note that roll control is secondary when recovering from a stall. Restoring normal pitch and roll, he ...
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12 votes
Accepted

How does the Boeing 777's yoke of both the captain and the first officer have synchronized movement?

From the FCOM v2 (9.20.1): The primary flight control system uses conventional control wheel, column, and pedal inputs from the pilot to electronically command the flight control surfaces. The ...
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  • 45k
11 votes

Which CPUs and programming languages are used in new airliner flight control systems?

Note: I focused more on changes in aviation hardware and software than what's currently used since the question linked about programming languages is still current for "new" aircraft. I do not wish ...
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