CABLE vs FBW
 

Cable vs Fly-by-wire

Under Rumours & News in the Plane Down in Hudson River - NYC and Airbus crash/training threads there is much talk about the good and bad with FBW. Every time an accident/incident happens with a FBW aircraft, this discussion always comes up. Perhaps a seperate thread dealing with "Cable vs FBW" might be in order.

Myself, I'm a "cable guy". I've always like the idea of being "connected" to whatever it is I'm doing, whether it be flying airplanes, driving a car, truck, or boat. The idea of electric signals being sent to some computer that has to think about what it is I'm trying to accomplish, and then sending that signal to some other computer to actuate some other device, to me seems absurd. Granted this can all be done in a split second supposedly, but it still isn't a mechanical link. I dread the day that FBW gets into the automotive, or maritime industry. If someone will prove to me that FBW is safer than cable, perhaps I'll "come of age".

OK, I've started this thing. Does anyone care to continue it?:)

Which is the most recent true "cable" (large) airliner built? 757/767 was not... ;)

NoD

I understand your thinking, but this could turn into yet another Boeing/ Airbus slagging match!! :ugh::ugh:

Rgds

CL747

Well
 

Historically, FBW was developed for military a/c where instability was part of the control regime. A/C were too demanding of human control input, and many a/c could only be flown by computer. Military requirements are light years away from low and slow, there are dozens of missions, not just one. It will remain a discussion for years, I think. AB have proved the mission consistency of the concept, but no format is accident proof. When an argument is sliced as fine as FBW vs. (sic) Cable, it becomes merely preference, and that having developed through time. To a proud pilot, FBW seems arrogant, to another it seems preferable.

The bottom line? How proficient is the Captain and FO on either format?

AF

It has been for over a decade.
Drive-by-wire throttle has been in some Toyotas (and no doubt many other cars) since at least 1998 that I know of. I have one of those engines transplanted into one of my cars.
The braking system is also being dabbled with, Mercedes for example have or at least had a system that varied the pressure to the calipers based on how quickly the pedal was pushed; In a panic stop it'd sense you stomping on the pedal and so direct a lot more pressure than normal into the system.
Electric steering is also being looked at and has been tested on company tracks. By electric, I mean there is no mechanical steering rack, etc.

It's here already.

"Which is the most recent true "cable" (large) airliner built? 757/767 was not... "

Ah.....three guesses. The DC-ATE.

18-Wheeler -

I was not aware of the things you listed. I won't be buying or riding in any of those.

For young folks: he means Boeing MD-80.

For not so young folks: he means McDonnel Douglas DC-9 Super 80.

FBW or not, I don't care. If the aroplane has proper type certification and is properly maintained, what intersts me are: size of the paycheck, days off and stability of the roster. Both fly-by-cable and fly-by-wire aeroplanes never failed to return me safely to ground. I have no reason to believe that fly-by-hydraulics will be different.

Automotive fly-by-wire is inevitable, because the autonomous automobile is inevitable--i.e. a vehicle that does the driving for us. I've written about this, and yes, I've heard all the pry-my-car-out-of-my-cold-dead-hands outrage, but you're wasting your time resisting it.

We live in an age where driving skill is rapidly declining and where distractions are rapidly increasing. Sure, there are Michael Schumachers here and there, but the vast majority of motorists have no idea how wide their vehicle is, which is why you see them driving down the middle of the two-lane road, and are as talented at skid control as they are at playing the twelve-string guitar (which, incidentally, is why a considerable number of new models have FBW stability-control and anti-rollover platforms).

So in a decade or two we will have a nation of drivers (at least in the U. S., unlike Germany, say) who have only enough driving talent to back the car out of the garage and put it into drive, and who have bought their car specifically because it offers Internet connectivity, video, and a variety of voice and other comm systems. They will _require_ an autonomous car.

The interesting thing is that all of the hardware to make this work--yaw sensors and other accelerometers, cruise-control radar, GPS, telematics and all the rest--are already on the shelf. We need some software, but DARPA has already shown that totally autonomous vehicles, without even a driver aboard, are eminently possible.

So if you won't buy or even ride in FBW cars, you're eventually gonna be walking.

Stephan Wilkinson

Centreline747 -
"I understand your thinking, but this could turn into yet another Boeing/ Airbus slagging match!! "

That was NOT my intent as Boeing already has some FBW technology installed in newer models.

Merely trying to determine the merits of one over the other.

So far no one has shown one being 'safer' than the other.

The Airbus A300 is a proper cable controlled aircraft, assuming cables to power flying control units is considered cable controlled.

If not and we mean non powered control aircraft we probably need to think about DC-7 or Lockheed 1649 Starliner as the last large aircraft with cable controls. (I stand to be corrected)

Even the afore mentioned DC-8 had some powered controls, Ailerons I think.

The Lockheed Electra has boosted controls which when de-boosted are just cable controlled.

I'll duck now while people shoot me down!

DC-ATE
Like I said I understand, I was just implying that we keep this a civilised thread, amongst the professionals out there, in what could be a very interesting discussion of the pros and cons of what is, and will become, the future in civil aviation and in the long term will affect all of us. :):)
I look forward to the replies.

Rgds

CL747

Yes, the DC-8 had powered controls. In fact they were all boosted. But in the event of loss of hydraulic power, there were cables for backup if only operating tabs. You could still fly the airplane. It just took a little more muscle!

Other than cost, I'm just wondering why we gave that up.

Interesting...
 

All,

Firstly I am not a pilot so please be gentle with the beatings......

However, from my limited understanding mainly gained by reading threads on here and researching both boeing and airbus use FBW on their later series and indeed earlier models of the former were servo assisted as the strength required to counter the pressures involved is immense.

As an observation I think alot of the preference of direct input comes from the reassurance that computers can and do fail so the direct connection does indeed leave the PIC with direct inputs to control the plane.

I can see advantages in aircraft design in using the FBW approach as cables will require unobstructed pathways down the length of the aircraft and these will require more maintenance as correct tensions and lifecycles need to be observed. I would envisage it be easier to route multiple redundent wire looms than cables.

The major issue I believe with the FBW approach is the involvement of the computer and how much this takes away from the PIC. There are also the issues of computer failure (multiple redundancy should prevent this being an issue). I cannot answer whether the above does indeed take any feeling away from the PIC but you guys would be able to answer that better than me.

Interestingly I think the whole boeing vs airbus argument is more related to sidestick vs yoke than fbw - my personal opinion is the sidestick seems to be less natural but I guess it is more what your used to.

DC-ATE. Could weight and cost have any influence on it?
Blooming great heavy wire cables against fairly light
electricery wires, and who needs to check cable runs
with a TENSIOMETER any more?

Storminnorm -
"Could weight and cost have any influence on it?"

As I have said a few times.....YES! I've always been more concerned with safety than cost. That's why I was critizised a few times for carrying a lot of fuel.

As we used to say. The only time you have too much fuel
is when the flames are licking round your *rse.

Centreline747 -
".....I was just implying that we keep this a civilised thread, amongst the professionals out there, in what could be a very interesting discussion of the pros and cons of what is, and will become, the future in civil aviation and in the long term will affect all of us."

While I am highly biased (and admit it) because of my age perhaps, I hope as well to keep it "civilised". I'm never too old to learn I hope even though I doubt I'll ever be in control of any FBW aircraft.....except perhaps in a sim!

I just want input on the safety issues.

OK.. a more serious reply than my 1 above ;)

Has FBW yet caused a fataility? The only accidents I can recall that seem the FBW was a "signficant factor" are QF72 (likely) and the Iberia A320 at BIO... neither of which had fatalities?

Has FBW saved any lives? Hard to say... but I guess it could be argued that at Habschiem (sp?) the FBW did save lives :D BA38 might be interesting to see if the FBW made things easier / gentler?

NoD

NigelOnDraft -
"Has FBW yet caused a fataility? The only accidents I can recall that seem the FBW was a "signficant factor" are QF72 (likely) and the Iberia A320 at BIO... neither of which had fatalities?

Has FBW saved any lives? Hard to say... but I guess it could be argued that at Habschiem (sp?) the FBW did save lives BA38 might be interesting to see if the FBW made things easier / gentler?"


Valid points. Guess I should not only include FBW as far as flight controls, but engine inputs as well.

As can be no doubt be determined; I'm against computers controling just about anything where a human is ultimately responsible for the final outcome. Oh, sure, we've come a long way. But everytime I see an "upgrade" with some computer file or program, there seems to always be a de-bugging period before it settles down. It keeps untold thousands of people employed though.

Guess I'm just from the 'old school' of K.I.S.S.

And.....if it ain't broke, don't fix it!