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#191
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"John Alger" wrote in message m... "John R Weiss" wrote in message news:S08%b.58709$4o.76896@attbi_s52... "Tarver Engineering" wrote... Since my servers seldom get me all the newsgroup messages and Google.groups can't seem to find the begining of this thread, please allow me to ask a question and pose some answers. And I apologize if any of this has been discussed previously. From the bits I have read subsequent to John's message above, I assume we are discussing the A-320 crash at Habshiem. If so, let me present some information relevant to the discussion, as I have not read anything as yet that indicates any of the posters knows much if anything about Airbus flight control systems. I do believe I am qualified to speak on the subject as I teach A-330 systems, which has a flight control system identical to the A-320. The A-320 which crashed into the trees in France was performing a fly-by demonstration, by a line pilot, not an Airbus test or demo pilot. The profile was to fly by at 500 feet. The pilot was making a scheduled revenue flight with passengers and came up with the low slow fly by all on his own. The aircraft was below 100 feet. This is significant to the incident (and not just because that is where we find trees). In the Airbus the computers have a group of flight control protections collectively known as "Laws". In Normal Law there is a low-speed, high AOA protection known as Alpha-Floor. Alpha-Floor is reached somewhere below Vls (the lowest speed the aircraft will fly with autopilot/autothrust on and sidestick in neutral), and prior to Alpha-Max (maximum AOA). At Alpha-Floor the autothrust commands TOGA power, and regardless of how much you pull back on the sidestick, the aircraft will not decelerate below Alpha-Max. It will just mush along at TOGA power until it runs out of gas or the pilot lowers the nose to accelerate. The low fly by was not an A-320 flight mode. The problem is, Alpha-Floor is not available between 100' and touchdown - otherwise you could never land! The pilot was expecting Alpha-Floor, but being too low, it did not happen. By the time he realized his error, he applied power, but it was too late. You can, in fact, hear the engines spooling up just prior to his impact with the trees in the video we show in class. That is what I have been attempting to communicate to Weiss. The aircraft performed as it should have. The pilot simply did not have an adequate understanding of his aircraft for the manuver he was doing. He also failed to follow the script. Two things the French apparently frown upon, expecially when used in combination. Yes. It is not just the French that believe the POH is part of the Type Certificate for an airplane. Lesson: if you don't fully understand your aircraft, it can reach out and bite you someday. Weiss is in danger every time he flys then. |
#192
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"John Alger" wrote...
The A-320 which crashed into the trees in France was performing a fly-by demonstration, by a line pilot, not an Airbus test or demo pilot. The profile was to fly by at 500 feet. The aircraft was below 100 feet. This is significant to the incident (and not just because that is where we find trees). In the Airbus the computers have a group of flight control protections collectively known as "Laws". In Normal Law there is a low-speed, high AOA protection known as Alpha-Floor. Alpha-Floor is reached somewhere below Vls (the lowest speed the aircraft will fly with autopilot/autothrust on and sidestick in neutral), and prior to Alpha-Max (maximum AOA). At Alpha-Floor the autothrust commands TOGA power, and regardless of how much you pull back on the sidestick, the aircraft will not decelerate below Alpha-Max. It will just mush along at TOGA power until it runs out of gas or the pilot lowers the nose to accelerate. The problem is, Alpha-Floor is not available between 100' and touchdown - otherwise you could never land! The pilot was expecting Alpha-Floor, but being too low, it did not happen. By the time he realized his error, he applied power, but it was too late. You can, in fact, hear the engines spooling up just prior to his impact with the trees in the video we show in class. From what you say here, it does not appear autothrottle was engaged (which also correlates with other descriptions I've read) -- apparently, the pilot manually moved the throttles from idle to Max. Is this true? Is Alpha-Max the stall AOA, or something less? Is there any "emergency override" that will engage the autothrottle when approaching Alpha-Max? |
#193
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"Paul J. Adam" wrote in message ... In message , Kevin Brooks writes Plus it never ceases to amaze me the number of folks who think that (a) bringing in enough aluminum matting (and we don't use PSP anymore) to build a fighter strip is a piece of cake (and trying to support a C-5 on one is a mean proposition), (b) installing the matting is all there is to it (no cut/fill, drainage work, or subbabse and base course prep required), getting the requisite engineer equipment and units into the site is an easy matter, and (d) this will all happen over a matter of a day or two. Laying in a fighter-length strip from scaratch is a *major* engineer operation, and quite different from that required to construct a minimum length rough field C-130 strip. Compare this with the effort needed to create HMS Sheathbill in the Falklands (which was a basic "land, refuel, leave or GLI" strip). It's *much* easier to pick a stretch of highway, fly in fuel bladders and maybe ordnance & first-line servicing - than to build a fixed-wing CTOL strip from scratch (lots of supplies and equipment needed just to build the runway before anything else arrives) The USMC's AV-8Bs did this to very good effect in 1991, for instance. And reportedly again during OIF, where AV-8B's used FARP's. Brooks -- When you have to kill a man, it costs nothing to be polite. W S Churchill Paul J. Adam MainBoxatjrwlynch[dot]demon{dot}co(.)uk |
#194
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Your question was (quote) "Can anyone conjure a F-35B Marine job that could
not be none by the navy?" The question was answered with specific operational capabilities (exercised in combat operations) that the Navy does not possess. You are obviously ignorant of the process by which "requirements" are generated and validated. You are obviously ignorant of how procurement #s are generated. You are ignorant of the numbers of aircraft resident in the USMC TACAIR inventory, and you are ignorant of how they are employed -- to wit, " I cannot get a good picture of a mission where the marines would need 400+ of them with all the support for them but still not have a decent runway!" Come back with some intelligent questions after you've done some research. "puttster" wrote in message om... yes, please do, but not with politispeak generalities. Instead, give me the best one practical example of the ideal mission as the perfect reason why the Marines would need to order 400+ F-35B's. "Frijoles" wrote in message hlink.net... No need to conjure. Try expeditionary air operations (FW and RW) ashore, as demonstrated in DS, OEF and OIF. TACAIR operations from amphibious shipping. How about assault support from amphibious shipping or from expeditionary locations ashore? Should I go on? "puttster" wrote in message om... Chad Irby wrote in message . com... In article , (puttster) wrote: Then let me ask why the Marines need the V/Stol capability. I cannot get a good picture of a mission where the marines would need 400+ of them with all the support for them but still not have a decent runway! Why are you limiting the situation to needing 400+ at once? The situation is more like "we need a dozen for this small brushfire war in a place where there are no good airstrips," or we need to put a small landing force in at this area, and the bad guys have a few planes, so we need a little fighter cover from the LHDs." If there are no good airstrips how would the marines get their gas, bombs, food, and all the other support? How (why?) were their Harriers used in Iraq? To support Marine actions on the ground, without having to go through the other services as much. They've been flying off of the USS Bonhomme Richard. Overall, Iraq hasn't been a good test of what we'd need the Harrier for. |
#195
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JL Grasso wrote:
On Fri, 27 Feb 2004 10:43:07 -0800, "Tarver Engineering" wrote: The A-320 which crashed into the trees in France was performing a fly-by demonstration, by a line pilot, not an Airbus test or demo pilot. The profile was to fly by at 500 feet. The pilot was making a scheduled revenue flight with passengers and came up with the low slow fly by all on his own. Actually, it was a charter flight. And not to split hairs, but the low/slow fly-by was discussed by airline officials and both captains in a prior briefing that day. The accident was officially caused by descent below obstacle height combined with a delayed application of TOGA power to exit the fly-by. The F.O. was also declared mentally ill for demurring from the above 'explanation'. Graham |
#196
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JL Grasso wrote:
On Fri, 27 Feb 2004 10:43:07 -0800, "Tarver Engineering" wrote: The A-320 which crashed into the trees in France was performing a fly-by demonstration, by a line pilot, not an Airbus test or demo pilot. The profile was to fly by at 500 feet. The pilot was making a scheduled revenue flight with passengers and came up with the low slow fly by all on his own. Actually, it was a charter flight. And not to split hairs, but the low/slow fly-by was discussed by airline officials and both captains in a prior briefing that day. The accident was officially caused by descent below obstacle height combined with a delayed application of TOGA power to exit the fly-by. Jerry So you're telling us that autothrottle won't work below 100 ft and to get TOGA below 100 ft you must apply it manually?... -- -Gord. |
#197
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"John R Weiss" wrote in message news:7lM%b.72046$4o.90913@attbi_s52...
From what you say here, it does not appear autothrottle was engaged (which also correlates with other descriptions I've read) -- apparently, the pilot manually moved the throttles from idle to Max. Is this true? Is Alpha-Max the stall AOA, or something less? Is there any "emergency override" that will engage the autothrottle when approaching Alpha-Max? Alpha-Floor protection is the automatic override. Autothrust does not need to be on, only available. Autothrust could have been active or not - it does not matter. However, Alpha-Floor is not available once the aircraft descends below 100' as I stated before, regardless of A/T status. The crew expected it, but it was not there becaue they were too low. When he realized his error, the captain manually applied TOGA power. Alpha-Max is prior to stall AOA - it is the top of the L/D curve. Here is a scenario that may help. Without touching the stick you bring the thrust levers to idle (this disengages the autothrust BTW). The aircraft will slow down to Vls and no more (the nose will pitch down slightly to maintain this speed). Now, if you grab the side-stick and pull it full aft (this will disconnect the autopilot) you will slow further towards Alpha-Max. Depending on your rate of deceleration and your rate of pitch (g), Alpha-floor kicks in somewhere prior to Alpha-Max - at that moment, Autothrust is automatically re-engaged, TOGA power is commanded (remember, your thrust levers are still at idle) and speed will stabilize at Alpha-Max while you hold the stick full aft. Depending on GW you may or may not be descending, but you will not stall. The aircraft in question never stalled - it is not possible in the mode it was flying in (Normal Law). You CAN fly it into the ground, but you cannot stall it. To move from Normal Law to Alternate Law (in which the aircraft may be stalled) requires multiple failures of key systems and/or flight control computers - none of which occured in this case. And, BTW: The gentleman is correct, it was a revenue flight (never said otherwise) but it was also a pre-arranged demonstration flyby of the new aircraft. This is why there is a very good video of the whole event. John A. |
#198
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On Sat, 28 Feb 2004 03:53:12 GMT, "Gord Beaman" )
wrote: JL Grasso wrote: On Fri, 27 Feb 2004 10:43:07 -0800, "Tarver Engineering" wrote: The A-320 which crashed into the trees in France was performing a fly-by demonstration, by a line pilot, not an Airbus test or demo pilot. The profile was to fly by at 500 feet. The pilot was making a scheduled revenue flight with passengers and came up with the low slow fly by all on his own. Actually, it was a charter flight. And not to split hairs, but the low/slow fly-by was discussed by airline officials and both captains in a prior briefing that day. The accident was officially caused by descent below obstacle height combined with a delayed application of TOGA power to exit the fly-by. Jerry So you're telling us that autothrottle won't work below 100 ft and to get TOGA below 100 ft you must apply it manually?... G'day Gord, According to Macarthur Job's description of this accident, the captain selected "...Open Descent Idle Mode to allow the engine thrust to be controlled manually.". Also, "...the crew deactivated the Alpha Floor function, to prevent the computerised control system from automatically applying power as the angle of attack increased." Phil -- Pfft...english! Who needs that? I'm never going to England. Homer J. Simpson |
#199
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"Kevin Brooks" wrote in message ... f-35B's seem like an Idea without a mission to me. The RAF , RN and USMC disagree Add the USAF to that equation--they just officially announced that they are interested in revamping their programmed buy to include some B models as well. It's all just a trick: the USAF wants the F-35Bs so they can rip the lift fan out and put the generator for the laser there. ;-) Honestly, now that I've said it, it doesn't sound that far fetch... |
#200
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