DW
Quote:
Originally Posted by RetiredF4
Yes, if you are a pilot and understand, how flying itself and management of abnormal situations is functioning in a human brain in opposition to an electronic gadget designed by engineers you will find some points to think over.
DW
How many times can I say this before it sinks in? The Airbus FBW system was designed by a group that included pilots.
True and accepted. You didnīt understand my comment, let me explain my answer a little bit. A computer is doing a failure analysis in simple terms by comparing things in a yes or no system. Out of more possibilities the system will end at a clear decision based on all information and earlier programming in a sequential evaluation process. You can explain that one better than i can, therefore i stop there.
We human pilots have the tendency to grasp all available information at once and in a sum and draw the nearest conclusion out of the available information, the knowledge and our personal expierience. We start problem solving with the nearest probable cause, which might be wrong. The more possibilities there are, the greater the danger to start with the wrong conclusion.
Back to the different laws, if those are not displayed in detail by the system, the degradation of subsystems is not clearly recognizable in such a human thinking process. Itīs not only normal and alternate and direct as you say, its complicated as the excerpt of the manual in my previous post clearly points out.
DW
And you're not answering my question. You've got five failure modes there (you didn't bold "In the event of temporary loss of all electrical control:"), only one of which is relevant to the case we're discussing and two or three of which have never actually cropped up on the line. From a piloting perspective the only significant failure mode that requires a different approach entirely is mechanical reversion (i.e USE MAN PITCH TRIM ONLY).
See above. Iīdidnt answer the question first, because your thinking into that matter is that of an engineer and not that of a pilot. But you are talking to those here and tell them itīs simple three cases and just do that and that. In hindsight you are right, but in reality the crew didnīt know in what kind of law they ended up, wether they had what kind of protections, wether it was ALt1 or ALt 2 or Alt 2b or whatever sublaws are possible and they didnīt grasp the consequences of this degradation and couldnīt base their decision making on that knowledge.
DW
Knowing what those modes mean is helpful, but not crucial. The only thing that *is* crucial is that outside Normal Law there are no protections and as such, more care must be taken.
This statement is again not true. Knowing the mode you are in is not only helpful, it is mandatory at some point of the game, and not knowing of the consequences, of the amount of degradation might become crucial, because not knowing might agrevate an otherwise simple situation. Outside Normal Law there is a big variety of protections available or not available, dependent on the individual failure and the degradation the System deems necessary.
DW
Quote originally RF4
And the main problem is, that you normally donīt fly that thing, but you are being flown while monitoring. Except when the sh*t hits the fan.
DW
That is the fault of the industry, not the aircraft or the systems. Even then what you're saying is untrue unless you take a very narrow definition of "flying" to mean direct surface connection, because the flight computers will do whatever the pilot requests them to do (just as their electro-mechanical/hydraulic predecessors did) unless what the pilot requests threatens to damage the aircraft.
Why are you always talking about fault? Any discussion with you ends in statements concerning blaming somebody. I didnīt mention anything concerning who is responsible for that fact concerning hand flying time, i only stated the fact, and you should accept it as ist stands. If you tell people to fly the aircraft in alternate law like you do it in normal law, then that statement is misleading. In normal law you only do takeoffs and landing and everything is done and monitored by the computers. In alternate law the roll yaw is direct, to point only one difference. The THS trim might work or might not work, and so on. Itīs different to normal flying and it is differnet to manual flying in normal law (if you meant that one with your term normal flying).
When faced with a sudden failure the knowledge of the nature and detail of the failure and the consequences of failures is paramount. Under that view its best to keep things simple, limited to few cases to aid in a quick and effective decision making process.
At the moment it seems to be a graceful degradation (from the engineering point of view as you say), which keeps the system on the highest possible level, but it is prone to misunderstandings by the human monitor and operator called pilot. A gradual degradation with few and easy understandable steps could be easier understood and could reduce the error possibility.
Go back to the previous threads, how much we all discussed here the different laws and sublaws and their consequences to input and output systems (Autopilot, FBW-System, protections, flightcontrols...), how many wrong statements had been written about them, and we all learned from these errors.
But again, i only wanted to clarify, that the graceful degradation of the Flightlaws is not that easy to understand like you say here. My personal oppinion, all others are entiteled to a different one.