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View Full Version : Fly by wire Airbus vs Boeing


grind king
25th Oct 2004, 23:39
Can anyone explain some differences between fly by wire on the 777 and Airbus aircraft other than the obvious thing between your legs?

WindSheer
26th Oct 2004, 11:16
Congratulations grindking, you may have just started another civil war - don't take offense by that.

Let me get the ball rolling:
Airbus did it first, Boeing thought "we'll have some of that".


As for the real differences, I am not that familiar with the 777 so wouldn't really like to say.

:ok: :ok: :ok: :ok:

Fly3
26th Oct 2004, 12:16
As I understand it Airbus make the protections "hard" ie they cannot be overridden by pilot input whereas Boeing allow the pilots to pull a little extra if they think they need it.

18-Wheeler
26th Oct 2004, 13:59
As I understand it Airbus make the protections "hard" ie they cannot be overridden by pilot input whereas Boeing allow the pilots to pull a little extra if they think they need it.

Yep.
Airbus = Computer flies the plane.
Boeing = Pilot flies the plane.

Captain Stable
26th Oct 2004, 14:21
Standard warning folks - this thread is not to become the usual Hairbrush Vs. Megajets barny. It's been done to death. At the first sign of it becoming so I shall close the thread.

Unless you can come up with authoritative comparisons, I suggest you refrain from posting. I further suggest that you should only post here if you have first-hand experience of both manufacturers' products. This does not mean "I'm a Boeing driver and my mate flies 320's and over a pint he told me..." stuff.

Sky Wave
26th Oct 2004, 14:25
So the great selling point for a boeing is that it will allow you to stall:hmm: . It baffles me as to how that can be an advantage. With terrain avoidance for example it must be far better in an airbus to be able to pull the stick right back without fear of stalling and climb away at Alpha Floor rather than a pilot trying to squeeze a fraction more out of the 777 and and ending up on the floor. What is the advantage in being able to stall.

FlapsOne
26th Oct 2004, 14:46
Don't y'all just a love a good ole Airbus/Boeing bash?

Whatever the debate, just bear in mind that, despite the popular rhetoric, you can fly the Airbus like any other aircraft. You can stall it, roll it, crash it, thump it, bang it etc etc.

It just depends what level of automation is on or off and what flying law the aircraft is currently 'enjoying' (either by design or failure).

You can fly an Airbus without pressing one button on the flight deck.......and it works perfectly well.

btw. Haven't got a clue how the 777 does it!

And Then
27th Oct 2004, 03:18
Hopefully Old Smokey will waltz accross to this discussion.

I think he is current 777, but with Airbus experience.

FullWings
27th Oct 2004, 17:07
I don't know whether I should post as I haven't flown in a FBW Airbus except for jump-seat rides and a couple of gash circuits in a sim years ago...

I think the biggest differences are not in the FBW systems themselves but in the pilot interfaces. A(irbus) have gone for low-feedback 'attitude demand' and B(oeing) have stayed (partly) with conventional controls and responses.

The 'control laws' in the B stay relatively constant but change with proximity to the ground in the A.

The B has a synthetic 'trim' to make people feel at home but removes the need to coordinate turns with the elevator up to 30degs AOB. It also removes the pitch couple from using engines, flaps, speedbrakes (not very well) and gear.

They both have a myriad of 'protections', the difference being the B's can be overridden by firm use of the controls or by disengaging the autopilots.

Both A & B have degraded 'fallback' control modes as the computers fail one by one... I don't know about the A but the B gets nicer to fly as bits fall off! (Electronically speaking)

Different ways to skin the cat but you end up with a feline sans epidermis at the end...

drag required
29th Oct 2004, 08:11
this paper might help, B777 and A330 are compared in a series of tests.

http://nathangb.com/wingfiles/files/authorityaircraftprotection.pdf

:cool:

Sky Wave
29th Oct 2004, 13:44
Thanks DR very interesting read

It's changed my view. It seems that if the Airbus system had a pilot overide it would give you the best of both worlds.

I can't believe the plans for automatic terrain avoidance wouldn't have an override, that sounds mad.

alf5071h
29th Oct 2004, 17:07
Sky Wave I have met the chairman of the report and I conclude that it may be apples and apples (ALPA etc).

As for auto pull up; the concept is to maintain safety. In the event, for whatever reason the crew have missed or ignored the awareness, alerts, and warnings that EGPWS provides, the aircraft will still fly in a safe manner.

EGPWS is an amazing safety device, but it is only a matter of time before we see the human fallibility of someone ignoring it.
The other aspect of auto pull up is not to remove control from the pilot, but provide him with an alternative (physical) view of the required action. A pilot may override the pull up, but I hope that most will be alerted to any previous error of judgment and be convinced that the system is providing the correct action.

I would also support auto pull up for windshear and some form of auto push / pull (control nudging) for TCAS.

Loose rivets
29th Oct 2004, 23:39
A couple of points, anecdotal I know, but I think it’s germane. (point noted from ModBod

About ten hours into my career, I was in the RHS of a DC3 going into Rochester. (The UK one.) For reasons that I won’t go into, we still had quite a bit of power on as we went past the little wooden hut at around 45kts. First I watched the cluster of waiting faces pan with us as we went by, then at my Captain’s face, then forward – to see what was making him pull that expression. It was trees.

I got on with the lengthy task of putting the gear up, while listening to twiggy noises hitting our parts at 45 kts. The aircraft had no business being in the air, but then something fortuitous happened. The ground fell away sharply cos of a highway cutting or similar.

It is entirely because a DC3 did not have ‘no’ in its vocabulary, (‘NO!’ in French) that we were able to make use of the sudden change in the terrain – a quite illegal excursion out of the envelope had bought us the time to take advantage of a lucky break.

I’m acutely (and to be serious for a moment, respectfully) aware of the accident that it could be compared with.

Years later, a take-off in a BAC 1-11 turned a little stressful when a fuel bowser appeared out of extreme heat haze. We shoved over to the right, confident that we would pass behind it…stopping was not an option. The real problem began when a trailer came into view.

If any electronics had interfered with our stick-shaking hop over that second unit, the results would have been obvious.

It seems that there is a positive consensus on the pilot’s final rights to take control, but can they be implemented instantly, and extreme cases trained for?