Originally Posted by
gums
My problem with the Airbus fly-by-wire implementation is two-fold: 1) Too damned many reversion sequences and autopilot connections with the flight control computers with their laws and sub-laws and sub-sub-laws....., then 2) Flying with aft c.g. that most planes would not be certified for.
As I've said before, the thing is that comparing FBW as it is applied to a fighter jet like the F-16 (constant correction due to inherent instability in the airframe) with how it is applied in an airliner like the FBW Airbus series or the B777 (to assist pilots in managing the flight on a stable airframe) is to ignore a fundamental difference in the design specification - i.e. a completely different set of problems.
The F-16 had to handle modes of operation that would be completely outside the frame of reference required by an airliner, and on top of that it was a pioneer in it's field - so it's hardly surprising that it was possible to "throw" the computer. While the A320 was the first fully-FBW airliner (aside from the H/S mechanical reversion you mention), it drew upon experience from the development of the A300 series - and before that - Concorde (which was effectively analog FBW - if you haven't checked out the Tech Log Concorde thread, I urge you to do so - it makes for fascinating reading).
The A320 series FBW control law reversion looks complicated on paper, but I can assure you that it was designed to behave in a completely logical manner in flight, and the design pattern it followed had input from line pilots as well as engineers - something that rarely gets mentioned. The FMC (autopilot) and FBW technologies are not that closely intertwined and can effectively be thought of as completely separate systems. The design of the automation as a whole was completely optimised for airliner operation, which is why looking at it from the perspective of FBW as implemented in fighters it's not likely to make much sense.
The analogy I like to think of is that you wouldn't try to plough snow with a combine harvester, despite the fact that the underpinnings of a snowplough and combine harvester are very similar.