Originally Posted by
misd-agin
The 777 works. You can debate FBW vs hydraulics, A vs B, but the 777 is a great flying airplane where the FBW is an invisible system. It just works. No mode shifts that catch you out. It just works.
Same as with the Airbus implementation - Airbus Flight Law changes exist purely to provide the pilot with as close to "Normal" response and handling as possible in the event of damage or systems failure. Boeing opted to use a servo-operated and software-driven PFC setup on the B777 and B787 as opposed to the passive Airbus setup, however this added complexity and made the manual bypass (the oft-cited 'Big Red Button') a mandatory inclusion in the system.
Originally Posted by
SMOC
FBW vs Cables and pulleys makes no difference to the yoke feel it's exactly the same, both are completely artificial. Under the floor is a mechanical set up just the same as any Boeing yoke which at some point connects to springs to provide artificially feel and some additional hydraulic/electromechanical resistance when required.
Exactly - tactile response has been, either in whole or in part, artificial since just prior to the Jet Age. The last jetliners to have purely manual reversion mechanisms were the B737 and DC-9. Manual reversion was impossible on widebodies because the flight surface resistance was way beyond the ability of human muscle power to counteract.
The only difference FBW makes on the B777 and B787 is that the artificial resistance is software-controlled as opposed to mechanical.
Originally Posted by
roulishollandais
I don't share your non scientific concept of invisibility for a control system who just works....until the failure and crash ! Your invisible banker never puts his money on your acount !
It's not invisible - at least no more "invisible" to the pilot than the equations behind the mechanical artificial feel systems used since the '40s.
Thus far there have been no accidents on the line put down to errors in FBW implementation - none.
Originally Posted by
tdracer
On ALL Boeing FADEC-equipped, the thrust command is directly linked to the throttle position.
On Airbus, the actual thrust setting feedback is visual via the "donut". People will argue 'til the cows come home, but IMO there have been enough incidents and accidents on aircraft with moving thrust levers that the perceived issues with the passive Airbus design aren't reflected in the real-world record.
On Boeing, there is no aircraft computer between the throttle and the FADEC - it's a basic design philosophy.
Same with Airbus. The FMGC can order thrust to assist control inputs, but it augments the original settings rather than overriding them.
Originally Posted by
SMOC
What are you talking about, AF296 crashed because TOGA thrust was applied to late, the plane didn't climb over the trees because it was already at max alpha for the slow fly-by and the engines took around 4 sec (which was normal) to get to any decent amount of thrust...
Spot on. With the way the aircraft was positioned and configured, the only thing the flight control computers could do was keep the aircraft flying by preventing a stall. The A/THR system couldn't command more power (as they were below 100ft RA - though that was supposed to be manually disabled), and as such, the only aspect they could control was AoA, by keeping it as close to theoretical Alpha Max as the conditions would allow.
Originally Posted by
Mac the Knife
"....therefore remove the requirement to trim as it's being done behind the scenes with no feedback"
Hasn't this created a few problems lately when the aircraft has significant amounts of trim in that the aircrew will only be aware of if they specifically look for it?
Is this not confusing when modes change or the AP drops out?
If you're thinking of AF447, the AP had already dropped out, and it was the PF's inputs that caused the autotrim to move the THS to an abnormal position. When we tested the scenario in an A320 sim, the THS would be held well shy of maximum deflection - it may be that the A330 was implemented differently. Regardless, the trim's movement and position is not invisible - it is clearly visible via the movement of the wheel and the gauge inset at the trim wheel's hub.