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@rudderrudderrat
Absolutely. The approximate V/S when the FDs came back online was 1500fps. Even if neither F/O followed the correct procedure - which was to disable them - you'd hope that the PF would ignore them as a matter of course until things were stabilised. The reason I'm sceptical about the FDs being responsible for the NU inputs is because the inputs continue, and indeed intensify, after the FDs go away again - as well as the fact that he continues to feed in short bursts of ND even after the actual V/S starts falling away dramatically. I have to admit the possibility that the PF did indeed choose to follow them, but I remain to be convinced. It appears more likely to me that he was chasing the pitch on the artificial horizon as the aircraft entered the buffet at the apogee of the climb and thence into full aerodynamic stall. |
IMO
I've lost control of the aircraft Just in time : 2 h 11 min 32 - Maybe, mm43 could add it to his graph.
(…) I don’t have control of the airplane any more now I don’t have control of the airplane at all I"d like to know what is in (…) ?
Originally Posted by DozyWannabe
as I said earlier, the FD is for navigation - not aviation.
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Originally Posted by CONF iture
(Post 7195073)
Try again when you built some experience maybe.
And by "navigate" I do mean in three dimensions - you can follow a pre-programmed departure routing with them and you can use them to guide you to waypoints, but there's no way they should be used in emergencies as they're simply a proxy for the autopilot. Which, as was pointed out in the "Children of the Magenta" video, is not capable of flying recoveries or avoidance maneouvres. The FD can tell you where to go, but it can't tell you how to fly (or in other words - "aviate"). |
HDG/VS? Indicating ? Chronic right turn? Chronic Nose Down? What was she doing at a/p loss?
Come left, ascend? wtf? What did PF have at the outset of manual control? Doze, would you lean toward an inertial problem as well as ADR? Follow Me Flyboy..... |
Originally Posted by Lyman
(Post 7195113)
What was she doing at a/p loss?
No attitude reached prior to the PF taking the stick was unmanageable, and she didn't actually depart from controlled flight at any point until she hit the stall. |
No attitude reached prior to the PF taking the stick was unmanageable, and she didn't actually depart from controlled flight at any point until she hit the stall.
You're not wrong..... |
Been BZ looking at the Indonesian crash, so not much to contribute here until last two pages ( GASP! world record for posts RE a single crash, ya think?).
Doze has it nailed. Period. @ Wolf Our problem in the Viper was we could not command nose down once we exceeded the magic 27 deg AoA limiter by zooming up and having speed decay faster than the FBW system could compensate for. The HS was already at the maximum( leading edge full up to keep AoA under 27 deg), but the pitch moment was such that nose down commands didn't work. So we settled into a fairly comfortable deep stall. The AF jet did the same thing except it wasn't a "deep stall", it was "deeply" stalled. Back to Doze.... So we saw the AF jet get into the stall the same way we did. Hold the nose up and at such a steep angle that you run outta those "lifties" before the system can command enough nose down pitch moment. Remember that we flew at a much further aft cee gee than the 'bus. Not having the AoA being used by HAL contributes to the problem, otherwise HAL would have commanded nose down regardless of the SS position/command, just like the Viper. Not so with the 'bus. The PF still had the ability to command nose up when the "protections" should not have allowed an excessive AoA. I go with some of the other folks here with "light" experience, that the AoA doofer works very well even at low speeds, and I don't recall seeing any speeds below 100 knots or so. I think the control laws may be under scrutiny by the accident board in this regard, and I would move to use AoA sensors as long as they were not frozen or were way outta agreement with each other. Ours were used/displayed even with WOW, but the speed display quit about 60 knots!!! Hmmmm, same number as the 'bus, and I'll link my LEF failure video so you can see the AoA bracket "cage" as I slowed down on the runway. If anyone wants to see the video, chime in here. |
@Dozy:
The other reason is that the FD would have been taking it's information from the selected values, correct? According to the trace, none of the "Selected V/S" values during HN39's excerpt even come close to requiring a 15 degree NU climb. pitch bar guidance is limited @ +/-22.5° of pitch, 50° FPA, if that limit reflects the +/-6000ft VS limit it would be definitely above 15°. Once again this is IF!! not VLS protected. @CONF and Lyman: I've lost control of the aircraft If he was following the guidance he would have released the SS and even pointed the nose down between (02:10:55) and (02:11:05) in HN39's graph instead he went back to 15 pitch° |
Originally Posted by DozyWannabe
Are you saying you *would* try to follow the FD bars in an emergency? I'm pretty sure that's not what they are designed for.
If only the PF could have said : "Give me 1000 fpm in descent" Or the PNF, instead of calling the captain back : "We're high I give you OPEN DES" I think we are pretty much on target here or we have not been that close before ... |
Thanks for the vote of confidence gums - much appreciated.
Just to clarify - the computer does make use of AoA, otherwise alpha protections wouldn't work. Those protections are *inhibited* in Alternate Law because the systems are not designed to work from a single data value (in this case AoA). Even in Normal Law however, the flight computers cannot *command* the aircraft to change attitude without input from a human pilot or the autopilot (which is a separate and distinct system from the flight computers). Alpha Protection simply maintains pitch attitude slightly below alpha max for the current airspeed. The only positive command that comes out of the protections is when Alpha Floor orders TOGA - and again, autothrust needs to be functional to do this. @CONF - Obviously anything we have regarding FD behaviour is completely speculative. If rudderrudderrat's right (and I'm inclined to think he is), then the FDs would have been reset to the attitude the aircraft was holding when they returned. Given the significant drop in V/S alone those FDs would not have looked stable for very long. The lack of any indication on the CVR that they thought they were out of the woods, along with the fact that they never tried to re-engage automatics when the FDs came back casts some doubt on the "followed the FD into stall" theory. It's a possibility for sure - but not a certainty. |
Originally Posted by A33Zab
pitch bar guidance is limited @ +/-22.5° of pitch, 50° FPA
Once again this is IF!! not VLS protected What would be the command ? It is IMO a scenario not foreseen on the design board. At that time it was already in fully developped STALL.... If he was following the guidance he would have released the SS and even pointed the nose down between s55(02:11:05) and s65(02:11:15) in HN39's graph instead he went back to 15 pitch° |
@ Doze
J ust to clarify - the computer does make use of AoA, otherwise alpha protections wouldn't work. Those protections are *inhibited* in Alternate Law because the systems are not designed to work from a single data value (in this case AoA). Even in Normal Law however, the flight computers cannot *command* the aircraft to change attitude without input from a human pilot or the autopilot (which is a separate and distinct system from the flight computers). Alpha Protection simply maintains pitch attitude slightly below alpha max for the current airspeed. The only positive command that comes out of the protections is when Alpha Floor orders TOGA - and again, autothrust needs to be functional to do this. Fer chrissakes, Doze, the system did not limit the AoA or we wouldn't be here trying to figure out what happened. I must admit that our primitive FBW system didn't care about attitude - it limited AoA and gee with no regard for aircraft attitude. Different requirements and missions. We could pull power back in level flight and let the system "trim" up command ( AoA, not pitch). In other words, trimmed for one gee and let HAL do his thing. When we got to 27 deg AoA we were at 1 gee max command and actual parameters. Sucker would then slowly begin to descend at 27 degrees AoA. If we had not entered the deep stall bucket with bad pitch moment, then we could simply push forward on the sidestick and fly out. On one of our engine failures, the guy ejected and the jet got to the AoA limit and slowly descended until it hit the ground. St and level, as no sidestick roll command and HAL kept roll rate at zero. One jet actually landed by itself and only suffered a broken main gear. The guilty pilot ( ran outta gas and tried for a deadstick landing until about 300 feet) looked back after landing in the chute and the jet was there with the strobe flashing and the EPU still pumping out poisonous gas, heh heh. They used the jet for maintenance training afterwards. Our gee command was manually controlled by using our trim switch. So default was 1 gee, but we could trim to 3.5 positive gee or about 2 negative gees. The 'bus system doesn't work the way ours did and still does. So I would recommend that once outta primary law that the system uses something like we had. |
@CONF:
Excuse me, autoflight is complicated and information considering this issue is very fragmented, I am trying to filter and report the relevant bits and pieces related to this specific case not any other mode or CONFIG.
That doesn't mean information is complete. Whatever the altitude ? Once again is it sure you'll be VLS protected if you're already 40kt below ? What would be the command ? It is IMO a scenario not foreseen on the design board. That's a clear statement!, Such a statement is not made in the FG section. AP disengagement doesn't prohibit the FG to calculate FD guidance and display. -The expected guidance would be LEVEL OFF!? ......and handle speed (Identical as AP/AT command when VLS is encountered in CLB mode) -Agreed. but there are different views on how such a scenario was initiated and did developped. -Thx for correction. The following snippets concerning AP/FD Speed Protection: (Read the NOTE: section) What do they mean with -except level off is performed-? level off as result of this speed protection or level off due to CRZ? ---------------------- Clearing of FD commands Manual clearance ..... ..... 1// Logic-controlled clearance a/ Axis-by-axis removal .......
b/ FD disengage request The FGE requests the FCU to disengage the FD if:
When the FD is disengaged, the A/THR changes to SPEED mode to bring the aircraft speed back in the flight envelope. -------------------------------------------------- NOTE: AP/FD speed protection The speed protection is applied, according to the mode, in order to protect against Vmin or theta max (=22.5°) when climbing or Vmax when descending with the following load factor limits: Max pitch attitude limitation is set to theta max =22.5° The protected modes are OP CLB, OP DES, CLB, DES, ALT*, and V/S-FPA except when a level off has been performed. Description of Vmax/Vmin:
With AP engaged, when V/S-FPA target is not held by the AFS because it is excessive, the AP speed protection is activated: a triple click aural indication and a flashing amber box around V/S or FPA mode and target on the FMA are commanded by FMGEC.
http://i474.photobucket.com/albums/r...rotectAPFD.jpg |
Beating the dead horse
c'mon, folks.
We know with a large probability/certainty that the jet was flown at a high attitude as the airspeed slowed and that all the "protections" did not keep the jet from exceeding the stall AoA or even the basic limits we see in the manuals. Basic design problem and pilot problem, IMHO. Without being a fellow ghost to talk with the PF, we'll never know. And I ain't willing to meet the dude in that great hootch bar in the sky just yet and ask him, "just what the hell what were you thinking?". Many of the graphs we have seen here should be examined by the accident board, but the focus should be on the basic control laws that the jet employs. I also have problems with training and exposure to the worst conditions. this thing started with a fairly benign sensor failure, then escalated to a tragedy. Some crew failures, some design deficiencies. It all added up. Hope to hell that the board recommends some changes to the control laws and reversion sequences. |
New pages for the flight manual
O.K., I can't resist. Got the QuickTime video finally, and post it here.
This is not like the AF jet crash. Got the jet back to the ramp. No previous documented failure of the leading edge flap or successful landing. Next one required an ejection. This one was a 100% maintenance failure, as the troops did not insert the "keeper" pin into the drive tube from the hydraulic motor to the flap drive tubes after some work. So the sucker slipped out about the time gear handle went up. You have to have a QT extension on your browser, or you download the file and then use the QT app to view it with the audio. Do I have a lotta sympathy for the AF447 crew? Not really. I was faced with the first of its kind and used every trick in the book, not the 30 previous pitot system failures. I also point out the immense help my FBW laws provided. Instead of a huge roll into the bad wing, HAL tried to keep roll at zero roll rate. Turned out that I had about a pound or so authority beyond the laws, so was able to steer left and right. Pitch worked as advertised. The box with an "x" after tower told me I had traffic was a radar lock I used with the cosmic stuff we had. Finally got a visual, then back to the approach. I also did not notice how quickly speed went down once speed brakes were extended. They also influenced yaw. Discussed all that later for next troops wit the same problem. Nevertheless, stabilized at 170 knots and cruised in. Biggest surprise was the touch down and speed bleed off. Once mains on the ground was a piece of cake and aero braked to slow down. Normal touch was about 120 knots. The problem: http://i120.photobucket.com/albums/o.../rightwing.jpg The QT video: http://www.sluf.org/warbirds/lef-landing.m4v Will edit if not working. |
A33Zab;
What do they mean with -except level off is performed-? level off as result of this speed protection or level off due to CRZ? As I understand and recall it, a "level-off" is a term that refers to a flight phase change from either the climb or descent phase to a leveling off (no change in altitude), even if the level-off is temporary. If the altitude at which the aircraft is leveled off has been entered in the MCDU PROG page under "CRZ", the FMGC enters the "ALT CRZ" mode for speed and power settings which use the CI and other information entered into the MCDU by the crew either at the start of the flight or during the manoeuvre. "ALT CRZ" is displayed on the PFDs. If the level-off altitude is different than the altitude entered in the MCDU PROG page under CRZ, the FMGC enters the "ALT" mode and displays "ALT" on the PFD, indicating the difference between the MCDU setting and the captured altitude. I suspect the meaning of the quoted passage is, the protections afforded in the listed modes don't apply/aren't available when the aircraft is leveled off...which makes sense. (It's interesting to note that ALT* is a protected mode). |
Hi PJ2,
It's interesting to note that ALT* is a protected mode. ASN Aircraft accident Airbus A330-321 F-WWKH Toulouse-Blagnac Airport (TLS) |
Thanks rrr, yes, I recall the accident well. The alt-capture pitch mode applies to the Boeing as well, if I recall.
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Originally Posted by gums
(Post 7195648)
The 'bus system doesn't work the way ours did and still does.
So I would recommend that once outta primary law that the system uses something like we had. The reason Alternate Law exists in the first place is to provide a graceful degradation so that pilots aren't dropped from Normal into Direct, which would be too jarring. It also provides a partial set of "soft" protections in certain circumstances. This makes sense for an airliner - it's not bad design. One of the crucial factors that Airbus FBW pilots must (and usually do) understand is that the protections cannot be relied upon outside of Normal Law. There were no protections as soon as Alt2 was latched - the pilots should have been aware of this. You can have computers operating on single data sources in a fighter with a bang seat, because if everything goes to plaid the single human occupant can egress safely in mid-air. This doesn't work for airliners, so the only safe way to apply the technology is to check, cross-check and re-check. |
Gums
Will edit if not working Thank you |
Originally Posted by gums
(Post 7195902)
Salute!
O.K., I can't resist. Got the QuickTime video finally, and post it here. Only problem is you make it look too easy - the still photo of the wing always looked seriously scary (at least to me), but in the video you make it look like a non-event. Makes it all the more impressive. |
Thanks Infrequent and JC.
You must realize that I did not turn on the VCR we had ( first jet with the "home movies" for de-brief, heh heh) until I had done a few things and then had the gear down. All what I did was in the after action report for other pilots with the same problem. I also apologize for poor R/T with tower, and I also had the private VHF with Rooster for stuff, so some radio is private and other is to the tower. My basic point is to show how one can handle a serious problem without doing a lotta stupid things. It is called airmanship. Also did not turn on the VCR until base leg with gear down and a fair semblance of control ( 17 pounds of authority and about 15 - 16 pounds required to hold wings level according to the recorders). I then turned on the narration for last two miles in case I had to jump, and I wanted it for the accident board. Silly me. Funny thing was using the auto-ack radar to find the C-141 who was trying to land the same time I was, heh heh. So that box with the "x" you see for a few seconds was the lock-on, and I kept looking for that sucker because the jet seemed O.K. at that time. All is well that ends well. It was the only time I ever came home and my wife knew that something serious had happened. You damned right. First and only time my maintenance guys let me down, and when that senior NCO showed me the missing cotter key my legs got all gimpy. Oh well a good thing that saved a few later folks with the same problem - most mechanical failures and not maintenance. |
Owain
"I think you've got it about face again - +ve sidestick is ND - he's lingering in NU." Exactly. Precisely. Clearly. With a focus on that, let's compare what happened at the STALL "BREAK" with what happens at the unlatch of the autopilot....... Just as PF has got the flight path mastered, (per BEA), the Bars return, and he follows with aft stick (he is told he is LOW), BUT, with a trained in response that did them in he selects TOGA, and just enough NU from the Thrustline to get to AoASTALL 9.6. and bob's your uncle. That is how they STALLED. How did they CLIMB, to get into such a precarious position in the first place? The same way. The same way the other flight climbed, they pulled. BUT WHY? Following "orders"? Of course, how else? I have been trying to get it into the discussion for a while, let's take an honest look at the pilotage. It was not impatience, wholly, or even partially that started the climb to disaster, it was the data on the Flight screens. Garbage in, garbage out, climb back up to the flight path. It was not Turbulence, nor an UPdraft, it was the boxes. Why would the pilots insist on climbing, especially when the REC was discussed, and agreed to be not partial to ascent? Why would they persist in the climb? Follow me, flyboy..... The siren song of an aircraft who cannot tell the truth. It is not her fault, these things happen. The FD bars were lying at the outset, it is what got them into the zoom to begin the disaster, and when the PF had it sorted, they returned, just at the critical point when the Pilot had it "mastered" You all believe what you will, or what you are told. The first response to the bars in PITCH and RUDDER got them onto the dirt road to HELL, and they were close to getting back on the tarmac, but fate.... Look at the teeny little hook on mm43's excellent graph, where the FD comes back just prior to the STALL...That's TOGA, a pinch more NU, and "crazy speed" follows, STALLED. Of course he was flying the FD's, they were on, and the a/c doesn't show them if they "lie".... But at the first? What 'started' the accident? To me, I always wondered why everyone's attention was deliberately focused downstream, to get into reams of post STALL/ZOOM conjecture. That is where the crash began, when the pilot followed his data, to climb. And climb, and.....climb. At first the a/c was hesitant, almost sentiently resisting the ascent, but in the end, she Nosed up, and that was that. Gargabe in, garbage out. "Why would an experienced pilot keep pulling, against his better judgment?" To bubbers44: He DID, but not due lack of 'stuff'. You would do what he did, so would PJ2, so would gums, Machinbird, and on.... In the !!!!, you fly instruments. Everyone does, it is trained. Of course there's more, but I prefer to start at the most important cause, and let follow the chain behind. |
Look at the Stall point. With his stick at aft 12 degrees, he moves it forward about 20 degrees, instantly, and he already has TOGA, so to me this shows a textbook STALL recovery. It also shows, via the AoA green line, that the a/c did break, her nose drops. Follow the AoA line, and mind the sequence of "bumps". I think each of these bumps is a secondary STALL, then Tertiary, etc. He is trying to "fly" on the "good" side of the Break. Each time it breaks, he thinks he is STALLING, then recovering. He has the authority to arrest the "descent" (stop the NOSE from falling further) each time it breaks, sad...... and thanks to the THS. The STALLWARN is counterintuitive, at this point. I think he hears the WARNING as an "About to STALL", instead of STALLED. This is how the a/c gets completely away from him, as all his forward speed goes away, and he refuses to allow the NOSE to drop seriously, into what may have been a recovery.
mm43. What an awesome graph. It is as if one is there, in the cockpit. |
Lyman,
i´m not following your asessment. As a pilot you follow the "intruments" as long as it makes sense. To follow a FD bar would be totally out of this world, when Altimeter tells you you are climbing above max altitude, when pitch tells you your nose is far too high, when stall warning screams you are stalled, when VSI shows values not common in cruise flight, when the aircraft behaviour tells you you are flying my airframe outside healthy parameters. I´m not saying that it might have influenced their thinking in some kind of way, but you can´t construct the whole accident around it. |
I am with Retired.
Hey Lyman! Are you postulating that the PF simply followed steering cues? What about other indications? basic crosscheck. Granted, the speed and maybe even altitude were questionable, but simply holding the basic attitude of 2 minutes ago would have been the wise choice, IMHO. Don't fool with the power, don't change pitch attitude. Don't just do something, sit there and analyze the situtation and then proceed. And I did not see that. On my LEF failure, I pulled power back and stayed where I was because the jet was not outta control at that point. Sure, I continued the climbout to gain feet - speed is life, but altitude is life insurance. I posted that video to show how one could handle a unique mechanical failure, and in marginal weather. If the basic cause of the climb was the PF following steering from the jet, then we have to train the folks for unusual instrument failures. As far as I know, the attitude reference systems were working as advertised. So just hold what you got and take a deep breath while figuring out the next step. The whole thing pisses me off. A simple failure due to icing or whatever, then an intentional change in attitude within seconds. |
hey gums,
He was flying attitude, obviously. He had a PITCH CUE, and a ROLL CUE, hence his inputs. Cross checking what? For all he knows it's a simple autopilot disconnect, UAS hasn't come up before, for him, and he's flying in NORMAL LAW, as he would be in for any autopilot drop not related to UAS. Retired? Of course he's steering, that's what he and the autopilot have been doing for two plus hours. He doesn't move to deselect throttles, because deselecting throttle AUTO and deselecting FLIGHT DIRECTORS is part of UAS, of which he is unconcerned. WE know it was UAS, HE DID NOT. NEITHER did, not at that point. So he handles the ship off the FD, easy peasy. Again, why with the alarm? CAVALRY CHARGE and MASTER CAUTION happen at every AUTO quit, so he just wants to get to PARIS. I am saying his level of concern is not up to what you want it to be, or should have been, because he just wants to NAVIGATE. Mistake? Boy Howdy, but how is he supposed to know? Besides, even if you're LOST, get a DF STEER or a PAR, right gums? No sweat. I think the FD was worms, and he took bad data and turned it into confusion, alarms, and STALL, by virtue of his reactions to what he thought was happening, which was NOT UAS. FD worms? Bad AirData? For how long, and how long was the ship "flying" with duff gunk? We assume the flight degraded because we have the gift of time, and back slapping consensus, we think that's how it went. I say BS. gums: What about other indications? basic crosscheck. Granted, the speed and maybe even altitude were questionable, but simply holding the basic attitude of 2 minutes ago would have been the wise choice, IMHO. Don't fool with the power, don't change pitch attitude. Don't just do something, sit there and analyze the situtation and then proceed. And I did not see that. This is all good, but coming from a pov that has the PF in the stockade, for doing dumb !!!!. He wasn't, yet most of us have him all "figured out". It was Not until 17 seconds (check, I think actually eleven) after the loss of AUTOPILOT the PNF announced "we lost the speeds, then". "then" as in, "Oh, Hello, we've lost our airspeeds." We need to look at all of it, including that PF was a simple line pilot, who wanted to get to France, and home, not some test pilot wannabe who wants to out maverick goose. He acted as though he was unaware that UAS was the call, did he not? His call seems to have been a vanilla a/p drop, and "let's us stick with the flightpath", right? |
c'mon, Lyman.
I was not an official test pilot, but flying the first few A-37's and F-16's I had to be one, like it or not. I am trying to predict the accident board findings, and I have the following findings for other pilots here to critisize: - Loss of airspeed sensor due to icing or other factors. - AP disconnect and then reversion to one of the alternate control laws - A climb to 2,000 or 3,000 feet above the planned cruise altitude. - Entering a stall due to airspeed decreasing and no "down" command on the sidestick - Failure of the "cosmic" flight control system to limit AoA commands or actual flight parameters WRT AoA - Convoluted flight control system laws regarding reversion when the primary mode is inop - Failure of the crew to realize that they were stalled - Failure of the crew to hold nose down inputs to get outta the stall - Failure of the PNF to "help" the PF in a timely fashion - Failure of the control laws to use AoA even when the airspeed data is unreliable - training inadequate for the line pilots/crews when sh$$$t happens. |
Gums, it's not that convoluted - Normal -> Alternate -> Direct. Couldn't be simpler. The only thing you need to remember is that protections are effectively off the table in anything other than Normal Law and more care must be taken when applying input.
The flight control computer system is not "cosmic" - it was only considered ground-breaking 24 years ago becuse it was the first, and the concept has formed the basis of most western airliners built since then. I've already explained why the use of AoA without a cross-check from another data source is inappropriate in an airliner configuration. If the AoA sensors have failed at the same time as the pitot tubes, then control would potentially be limited in a way that prevents a successful recovery. It's better to put it in the hands of the pilots to make that call - with the caveat that the pilots must be trained properly and thoroughly. |
A bit more complex than that Doze, and for good reason, also.
Look at the timing and cause of Pilot's initial inputs, and tell me he wasn't flying FD and bars. UAS is not simple. Had it been simple, the Airline and the manufacturer would have designed and implemented a system that would have made it mpossible for Bonin to miss it. A system that would have kept 447 flying, not guessing. You need to take a breath and back up a step, you assume a position of knowledge and design that is superior to the Companies you defend, and that is not the case. For all that, you don't have the answer, only a stubborn fallback to a system that is under scrutiny for autotrimming to and throug STALL, inadeguate warnings of degrade, and STALL WARN that makes sense only to non-pilots. |
Master or slave FCS (flight control system)
@ gums : your post #767 Thread 8 AF447
Editing 19.5.2012 @ gums : Reading too quikly your post, gums, and others, I mismatched the informations, thinking only to connect the Master/Slave and soft- and hard-limitation ! Sure Your Viper is hard-limited ! Shame to me ! I also deleted smillies. Your post shows your Viper is hard-limited (no possibility for the pilot to overcome the protection), as Airbus would be in normal law. I Deleted also smillies. End of editing. When soft-limited, the Flight control system is slave, the PILOT is MASTER When hard-limited (Airbus), the FLIGHT CONTROL is MASTER, and the pilot who is slave, has to look the film... |
Lyman - I spoke to my friend and the TRE over email the other day and they concurred with rudderrudderrat's assertion that the FDs would have come back indicating the current attitude. Bonin was already pulling before the V/S started dropping away. I'm telling you - he could have been following the bars (although I think it unlikely - it has to be considered as a possibility), he could have been following the ADI (which is my pet theory), he may have been completely thrown and trying anything. We don't know and aren't likely to know until the final report is out.
There *was* a UAS pitch-and-power procedure that Airbus disseminated amongst the airlines, and we know AF had a copy. This was not followed, and we do not know how AF communicated that procedure to its crews. For the last time I'm not defending any company, I'm simply keeping all options on the table. On the other hand I will refute folklore regarding FBW and Airbus if I know it to not be true, but that's about as far as I go. I have no "skin" in this game other than a desire for rational and evidence-based explanation.
Originally Posted by roulishollandais
(Post 7197729)
When soft-limited, the Flight control system is slave, the PILOT :) is MASTER
When hard-limited (Airbus), the FLIGHT CONTROL is MASTER, and the pilot who is slave, has to look the film... :ugh: |
"Completely false. The pilot is "master" in a hard-limited system right up to the point where he or she commands a maneouvre that would stall or damage the aircraft - and the aircraft will follow that command right up to the safe limit. The computer is there to help, not to hinder."
Item: Autotrim. Soft limit? Silent helper? Hard limit, eg: "Take this trim and....." Shall the master be given an "AUTOTRIM/DISABLE" toggle to prevent the Stabiliser from "Helping"? Can we see a priority alert for LAW CHANGE in concert with AUTOPILOT LOSS? Something different, and notable, not like the thirty seven items of maintenance logged? A STALL WARN that WARNS and an additional one that alerts "DEPARTED"? Dear DEPARTED, we are gathered here...... Focus, flyboy, you're ass is STALLED..... |
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Originally Posted by Lyman
(Post 7197782)
Shall the master be given an "AUTOTRIM/DISABLE" toggle to prevent the Stabiliser from "Helping"?
This is because with the conferrence of "master" on a pilot, with the power comes the responsibility. I'm completely on board with sympathising with the F/Os, who were thrust into a situation for which they were not trained - but that doesn't make the resultant aircraft handling any less inappropriate. I realise that I may attract flak as a non-pilot saying this - but even if the FD is telling you to pull up at an altitude that is several thousand feet in excess of the safe limit you discussed only minutes previously (remembering that this is only a theory), then airmanship demands that you ignore the d:mad:n FD and just set pitch and power, then try to keep things straight and level until the the danger has passed and the other problems can be resolved. |
"I've lost control"
Probably referring to roll rather than pitch?
|
Nice flying
Hello Gums,
Impressive VTR of that LEF UP landing. Good thing you kept AOA so low during the entire event. I remember that in the first half of the eighties a Belgian F-16 was lost with the same failure (albeit that, IIRC, the torque tube there really failed mechanically, not just loosened because of a forgotten cotter pin). The Belgian approach went well, but during the flare, the AOA went up too high and a quick roll over followed. Pilot ejected, but bailout trajectory was already about level (90 degrees of roll) so he did not survive. You are correct in your evaluation that all that was needed in the AF case was to hold the usual ATTITUDE and THRUST for a couple of minutes. The correct words/commands would have helped - CHECK PITCH (ATTITUDE) or SET PITCH ON THE HORIZON, not - you are climbing - I know - you are still climbing (etcetera). The climb did eventually stop, but the pitch attitude was still way off the mark, of course. |
Originally posted by HazelNuts39 ... "I've lost control" Probably referring to roll rather than pitch? |
HazelNuts39
"I've lost control" Probably referring to roll rather than pitch? NO. (...) "I've lost control", (THEN) "I don't have control of the plane, AT ALL"..... perhaps no controls? |
Originally Posted by Lyman
(Post 7198105)
perhaps no controls?
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