russ_ waters said:
You are aware that the Air France crash happened in part because the plane stopped trying to override the human who flew the perfectly airworthy airplane into the ocean, right?
I've seen the PBS documentaries on it and followed a couple aviation blogs shortly after the loss.
My problem with airbus is
in my opinion it is over-automated.
Pilot controls attitude not through traditional yoke & wheel but a joystick like on a computer game.
How (indeed whether) it provides tactile feedback is not clear.
In a traditional cable & lever setup the force on control surface is transmitted to pilot directly through the mechanical linkage. I believe this was current aircraft technology through B52.
So the airplane has a definite "Feel" to the controls and one can sense low airspeed by that feel.
Even Howard Hughes' WW2 "Spruce Goose" had that tactile feedback - its control surfaces were too big for a man to move so Hughes designed hydraulic system with force feedback to pilot's controls.
So - if you take away a man's sense of touch so he can't "feel" the airplane,
and you place him a nighttime blackout situation where he has no sight
and you take away all his cockpit indication (all 3 pitots are believed to have iced over and maybe both instrument static vents too, causing the computers to give up)
and you throw a zillion alarms at him (the computers crashed and rebooted several times)
and you change the airplane's flight characteristics (heaven knows how much ice was on the wings)
I wouldn't be surprised if he flew it into the ocean by placing nose down in a desperate attempt to regain
indication of airspeed. With static vents iced over altimeter was probably nonfunctional too.
I also believe that tactile feedback to a traditional yoke might well have saved that flight. It'd tell him he has adequate airflow over the control surfaces and needn't be diving.
So is an over-automated ship that's lost its automation still airworthy?
again - I'm not an aviation expert
but I've seen mantraps built into other designs.
And yes, I am a curmudgeon on this issue.
http://aviationsafetyconsultant.com/human-factors-and-the-airbus-fly-by-wire-control-laws/
Human Factors And The Airbus Fly-By-Wire Control Laws
Published on December 30, 2011 in Uncategorized. 0 Comments
One of the first fly-by-wire (FBY) control laws was developed by Boeing for experimental use on a B-47. It had a sidestick control and was straight stick to control surface. “Stick to control surface” means there is a proportional input to the control surfaces for inputs to the controller, in this case, a sidestick. Boeing named this the C* (C star) law.
Airbus claimed to use the C* law, but made changes in the way the sidestick worked. They incorporated it as a quasi automatic system like control wheel steering mode of an autopilot, which will hold roll and pitch levels as input by the sidestick in increments. In addition, Airbus changed the pitch channel to control flight path angle with airspeed selected by digital dialed input and incorporated non moving autothrottles and automatic trimming. These features removed important tactile and visual feedback information from pilots.
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Thanks for the good-natured gig on smartgrid. It is doubtless well intentioned but I fear its capabilities will lead to regulatory and business excesses.
I suppose that's why we are allotted but threescore and ten - in that time the world changes more than we can stand !
...still a slide rule guy,,,,
old jim
