Originally Posted by
Goldenrivett
Have the authors of this paper got it completely wrong then?
While john_smith makes an (IMO quite correct) one-word response, it might be worth (yet again) trying to parse what's being said. For one thing the article posted (which is a blog post - not a peer-reviewed paper) is very hit and miss with its use of sources (including an article from 1987 - a year before the A320 even went into service). For another, it makes assumptions about the reasoning behind design decisions which are at best speculative.
Furthermore it makes this statement:
...in an emergency with a traditional yoke control the instinctual grab by the PNF is something that is clearly visible and also inherently self resolves the control contention...
which is fundamentally incorrect. In an aircraft with direct cable control, the aircraft will respond based on whichever of the two inputs is physically dominant (which is not necessarily the right thing to do), and in more complex modern aircraft with apparently "traditional" controls, the response may not be immediately obvious. An example would be the all-hydraulic B767 controls of EgyptAir 990. As it turned out, with one crew member pushing forward on the yoke and the other pulling back, the result was a split elevator condition which exacerbated the aircraft's departure from controlled flight.
In fact, a lot of the potential objections made by a subset of the piloting community around the launch of the A320 were based on the (as it turns out, incorrect) assumption on the part of those pilots that they knew what the response of their current aircraft types would be when presented with control-based edge cases.
The Boeing FBW system in the B777 retained (or to be more precise, reimplemented) the tactile feedback, but this came at an engineering cost - namely that the hardware and software required to provide this feedback was as complex again as the entirety of the Airbus EFCS. The sole reason the Boeing system requires a physical bypass control and the Airbus system does not relates solely to the potential scenario whereby the feedback system itself develops a problem.
The fundamental principle of the Airbus design involved confronting a basic truth that had been around for some time - namely that with hydraulically-assisted or all-hydraulic controls, the tactile feedback the pilots were getting was itself an electro-mechanical simulation, and as such open to potential failures and complexities that weren't really necessary.
As a postscript, it's worth noting that the naysayers the blog post refers to were predicting a slew of accidents caused by the change in control system philosophy - and to this date there have been precisely zero accidents attributed to the change.