Well, for strictly Attitude Indicator...

Post #341,326 by S1mon_Jester 4/5/11 6:36:35 PM Reply	Well, for strictly Attitude Indicator... The GPS would be the obvious ideal replacement. For the pitot tube, though, there's not much to replace it with. A GPS can give you ground speed (which is different that airspeed), but should be close enough for government work (ie: keep the plane flying). The trick to it all is that there is confusion in the cockpit. Most computers (and pilots) forget that instruments can fail. There are (scary enough) recorded accidents from the pitot tubes being blocked (actually just one of them) where both excessive airspeed and stall warning were going off at the same time. The pilot couldn't resolve it fast enough and the plane crashed.
Post #341,334 by Another Scott 4/5/11 8:54:39 PM Reply	Thanks for the information. Wikipedia seems to have a good page on various failure mechanisms related to pressure readings, including several crashes. http://en.wikipedia....stem_malfunctions Blocked static port A blocked static port is a more serious situation because it affects all pitot-static instruments.[6] One of the most common causes of a blocked static port is airframe icing. A blocked static port will cause the altimeter to freeze at a constant value, the altitude at which the static port became blocked. The vertical speed indicator will become frozen at zero and will not change at all, even if vertical airspeed increases or decreases. The airspeed indicator will reverse the error that occurs with a clogged pitot tube and cause the airspeed be read less than it actually is as the aircraft climbs. When the aircraft is descending, the airspeed will be over-reported. In most aircraft with unpressurized cabins, an alternative static source is available and can be toggled from within the cockpit of the airplane.[6] :-( But it sounds like the ADIRU might have been at least part of the issue ... http://en.wikipedia....al_Reference_Unit Cheers, Scott.
Post #341,402 by Ashton 4/7/11 5:25:30 PM Reply	While I no-AI-chops, I did run Eliza on my Otrona.. And as regards the Airbus crash, it's already clear(?) that, perhaps just TWO Summary-deduction messages might have enabled this crew to achieve what the crew in the simulator did == keep the plane Flying: (Of course sans Black Box, the step-by-step road to demise remains speculation, however competent) 1) You have lost all reliable airspeed monitoring -- no pitot tubes operational 2) Reset thrust to (87%?) and vertical angle to +5 degrees to maintain critical flight attitude! {{sigh}} TMI is no longer just a wry/exasperated comment on the unsortedness of massive amounts of info, mostly-irrelevant to any object of search. TRIAGE needs next to be #1 in the mentation of all who write s/ware for such complexities as flight (or at, say, CERN: accelerators {cough} -- where life-threatening sequences could develop, not only involving the obvious radiation matters.) <stupidity rant 1-B> Seeing that scrolling mass of Unix-level factoids, so-like some arcane/unlabeled Windoze 'report' as it eats-itself == prima facie evidence that the designers of this system never even THOUGHT of the effect of so much serial, unsorted Stuff [even the abridged set sent to pilots] would flummox Any human.. not just one at 35,000 feet, within a massive storm at night, and needing to keep plane's speed within an absurdly-tiny limit of +/- 10 Knots or so. Watching NOVA's replay of the actual data which went only to the maintenance base was horrifying. NOR was there any procedure! for signaling to Maintenance: >>Help Pilots NOW<< How much more is needed to be known to rate this, overall as ... completely unacceptable planning, design and execution of their entire control-system 'philosophy'? Eh? (I have seen results of an unWise technician putting the giant ex-Minesweeper motor-gens for the Bevatron into 'Dynamic Braking' ... despite visual evidence of massive sparking, etc. == for which events, 'coast' was The Correct response, even if it might take hours+ for the suckers to stop. Several hundred $K/ many days wasted on stator rewinds via Westinghouse, etc. But no bodies.) And since most of these Airbuses DO operate in similar conditions, late-night, storms possible etc. I aver that riding in one of these amateur-spawned auditoria is, as of 2011 -- foolhardy, to say the least. </stupidity rant> Pshaw.
Post #341,414 by Another Scott 4/7/11 11:21:20 PM Reply	Thanks for the reminder. I just finished watching the "Crash of Flight 447" Nova show. It's very well done and presents a compelling case. http://video.pbs.org/video/1685933496/ (It was 85%, 5-degrees.) The fact that there were so many examples of 2 pitot tubes failing, and so many examples of pilots not going to 85%/5-degrees quickly is a smoking gun. The idea that a big airliner can stall at 35,000 feet if its airspeed is 10 knots off seems nuts to me! But I never thought about it before.... Better training always helps when peoples' lives are on the line. But I wonder how realistic it is to expect that pilots will be able to cope with failure of so many systems at once. Supposedly there are many fighters that cannot be flown manually - they're aerodynamically unstable and need constant adjustment by their flight computers. With the push to make airliners more fuel efficient yet faster, and the limited airspeed windows at altitude that are already present, it seems like the automation problems will get more severe in the future. :-( IIRC, there's been talk of requiring GPS backups to help in cases like this. I guess the thinking was a Garmin in the cockpit might have helped, but given all the turbulence and the klaxxons and the flashing lights, who knows if they would have had the presence of mind to look at it. And there's the issue that GPS gives groundspeed, not airspeed, and if you're at 35,000 feet in a 150 mph headwind, well... :-/ (The FAA is going to be having planes use GPS for navigation, not airspeed.) So much for that. Thanks again. Cheers, Scott. (Who doesn't get to see Nova on TV very often and will have to visit the web site more frequently.)

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