hi gums;
Yes, the gang's all here, but only momentarily! In wings level flight, AoA can be derived from the pitch and the inertial velocity vector regardless of the air data probes/cones. The Sluf and Viper HUD had a "zero sight line" cross, and usually the flight path marker ( FPM) was below it ( negative gees was something else, heh heh). That was your AoA in wings level flight. "Derived" in flight data work means usefully accurate and precise as well as timely and the FPM / FPV vs pitch method of "deriving AoA" in rapidly changing circumstances, is none of these. While the FPM/FPV display is inertially-driven this still requires a working ADR (AF447s were intermittent and, in the time period available, essentially unusable) and a working AoA sensor (Perpignan, frozen sensor, erroneous stall speed display on the PFD). The point I wished to make in regard to Lyman's statement that AoA can be derived is that it can't be in the sense that it could be used to display AoA when original sources as described, are not available. *When the A320 first came online, we were trained that the FPV Flight Director should not be used as guidance during a go-around because of the lag in the FPV as the aircraft stops descent and begins the climb. The justification was, following a lagging display could lead to reduced climb performance. I believe that's now changed and the normal FDs are displayed automatically when the thrust levers are pushed to the TO/GA detent. |
Of possible interest is the UAS table below from the A320, dated April, 1991. The table clearly provides pitch and power settings for all regimes of flight. This checklist is in contrast with what I think was and is a confusing UAS memorized drill & checklist combo. While the origins of the present mess of a drill / checklist are understandable (post Birgenair & Aeroperu), compared to this simple checklist which provides clear information on pitch/power settings for all flight regimes, the present drill remains open to interpretation as to when the safety of the flight is at risk. The present drill also requires a pitch change in cruise altitude when none is required.
While pulling a transport aircraft up to 10deg pitch while in cruise is a serious error, I think the memorized drill, if taught incorrectly or misunderstood (and it still isn't clear) can leave some pilots who may not get into the books very much, (as per DP Davies' thoughts posted earlier on 'working at the career' and learning) or otherwise just thinking about the drill and maybe asking questions, with the impression that "pulling up" somehow solves the 'problem'. Granted a 5deg pitch up at FL350 won't lead to stalling the airplane, but why destabilize the airplane in the first place? http://www.smugmug.com/photos/i-bgcK...bgcKZkd-X3.jpg |
Hi gums,
Quote from gums #829: "In wings level flight, AoA can be derived from the pitch and the inertial velocity vector regardless of the air data probes/cones. The Sluf and Viper HUD had a "zero sight line" cross, and usually the flight path marker ( FPM) was below it ( negative gees was something else, heh heh). That was your AoA in wings level flight." Three years ago (before you joined this discussion?), some of the "gang" chewed over this subject, and we gradually realised that - for various reasons - it wasn't as simple as we had hoped... http://www.pprune.org/tech-log/39510...ml#post5575204 |
:uhoh:
Wouldn't their Attitude Indicator showing a lot of blue sky given them a clue? Just asking! :bored: |
Presuming the AI was integrated into a working instrument scan, yes.
|
Derived AoA....
PJ2
Howdy....From Chris Scott, post #521, "Search to Resume" As CONF iture knows well, a good ball-park indication, without any actual numbers, is on the PFD in FPA mode (preferably with the FD switched off). The Pitch attitude angle minus (algebraically) the flight-path angle approximates the AoA. For non-Airbus pilots, the latter is indicated by the "bird" symbol. The snag, for this purpose, is that it also shows any drift in azimuth. So, when there is a lot of drift, it is not directly under the little black box* which represents the nose of the aeroplane. So sorry to get gums in the soup....took some looking. |
Hi Lyman;
Yes, that's what I'd figured was in mind as I know AoA can't be derived from any other flight or system parameters. I do think that someone "tuned in" to his/her airplane could make use of this information so in that sense it's another tool, subtle and not widely nor well-understood even in the instructing world, (in fact I know an airline that refused to authorize use of the FPV/FD and would not train or permit its use in operations). I think had they had the FPV they would have seen this, (quickly...time yourselves... 3, 5, 10 seconds with noise, buffeting, warnings and fright, what's the AoA? What angle are we going down at? Should I pull or push?): http://www.smugmug.com/photos/i-8Mjv...8Mjv5cF-XL.jpg |
2 degrees nose up attitude and cruise power would have made this accident a non event. Hopefully pilots will now not make the same m
istake they did. |
Once I jump, I PULL, the ripcord.....20000fpm descent, AoA +45, Pitch 8 ND.
Nope that's wrong, badly..... seven seconds. Adios. Is this our friends? |
TNX Chris and PJ for getting me back to Earth.
I realize that we had the AoA discussion way back before I started to comment, but I had read the threads with only one comment until after we saw the wreckage pattern and got into control laws and a deeply stall jet. As several had pointed out, a derived AoA might be possible but impractible, and prolly unuseable if the pilot wasn't used to using AoA on a dail basis as Mach did coming aboard the boat. As far as the FPV, it would likely be updated at a decent rate - maybe 50 or 60 times a second, same as the digital attitude display. The inertial velocities must be sampled at a healthy rate or your nav errors are off the chart. EDITORIAL NOTE: The current use of GPS is super, but I can see less maintenance and care for the "good old inertial" units. But back to the chase - if you are pulling and that FPV ain't moving the same direction as the stick, then you are in a heap of trouble. This is much easier to see in a HUD, as the pitch lines are "real world' and you can only see about 15 degrees total from top to bottom. However, they were extremely helpful maintaining a 3 deg descent angle or any angle you wished. A PAR was so easy it felt like cheating. |
gums;
Re, "A PAR was so easy it felt like cheating." :ok: Yessir, done them very occasionally in the DC9. Aside from Canarsies onto 31R, that was a leg to get! I must be out to lunch as I never realized you weren't on earth all the time! The reminder re 'derived' etc was a good one and it got me going too. bubbers; Re, "I think I know but Airbus training needs to include how degrading automation needs to let people understand the level of automation they are at." I trained on the A320 in 1992, the A340 in '99, the A330 a bit later and from the get-go all three laws as well as the protections were heavily emphasized, taught, practiced and checked in recurrent rides. We knew that in Alternate and Direct laws one didn't do anything rash, quickly or rough with the airplane. While it was complicated sometimes, the ECAM was / is very good and must always be done to completion. Forgive me but really, the people who do this work aren't dull or slow. Re, "2 degrees nose up attitude and cruise power would have made this accident a non event." Well, QED. That's about what the airplane cruises at. Monitor altitude, set power, wait, do the ECAM, get out the QRH. That's why I said very early on, "do nothing, wait..." It's not an emergency. Regarding pitch, two to 2.5deg NU is the pitch the A330 cruises at and the thrust is already in the CLB detent, so the airplane is immediately both stable and under control which is the first rule, 'aviate'. To change the pitch attitude, (arbitrarily or via the checklist), adds workload and increases the potential for loss of SA as one departs one's cleared altitude and minds the speed, heading, etc and it delays getting on with the ECAM while the PF is ensuring that the airplane remains under control. I surmise that these are the things check airmen argue about in meetings all the time. In my view the UAS drill and checklist is a mess and can, if improperly understood and taught or badly executed, reduce and not increase flight safety. One thing to note that those who fly these airplanes may not know is, a transport airplane can depart controlled flight very gently almost languidly and smoothly, without broadcasting what it's doing. In the departure from controlled flight into a severe loss of control there was nothing violent about this accident. Even the descent would have been "languid" in terms of pitch, roll, yaw, gee despite the buffeting. As you must know instinctively from experience, it isn't 10 or 15deg NU that would get the attention of a transport crew, it is a degree or two above nominal. So if the airplane is in stable, level cruise at 2 deg, then a pilot taking it to 3 to 5 degrees (yielding about a 1000 to 1500fpm climb), and keeping it there would require an immediate taking of control to stop a loss of control event and also regain the cleared altitude. Seven or eight degrees pitch at cruise altitude and Mach is positively frightening in my book. When the ATs disconnect, you'd have to bring the levers back a bit to maintain the previous cruise setting but you'd never overspeed the airplane if you left the TL's alone. Lyman; Re, "Is this our friends?" I don't know. I don't know why this happened. All we know is a bit of how. HN39; Re, "Yes, it is possible for AoA to exceed Alpha Prot in Auto." Absolutely correct. Ask any carrier flying into Mexico City in an A320 about the sharp left turn onto the 5's from the 160R of SMO with the speed right back, landing flap out and an encounter with a bit of turbulence in the turn. It will also occur if one retracts the flaps too early, AP on or off. |
PJ....
Re: your last image and questions (rhetorical though they might have been): AoA- about 23 degrees, going down at about 35 degrees and you should bleeding well push!... ? Have I understood the display correctly? ( I don't fly, obviously) |
As one image cancel the STALL Warning, temptation to pull can be strong, especially as indicated airspeed is increasing ... Suppose you was already pushing hard at this time.
Note how the big red chevrons do suggest me to pull too ... |
Mexico City has the only approach I have ever seen that intercepts the localizier at more than 90 degrees. Also the automation will level you off above the glide slope so you have to TF the altitude to not be high. Trick :mad: for those curious. Also they clear you for this long arrival then turn you in short so if you don't know about it you are way too high so have to speed brake the whole arrival.
|
How in the world did you manage to resurrect this zombie thread again?
Originally Posted by alogobotur
I started to read final report, but it is very massive text, and it takes a lot of time to read it.
Originally Posted by PuraVidaTransport
When the plane reverted to Alternate Law (2B if I remember correctly), engaging the autopilot was not an option. Once latched into alternate law, the autopilot can not be reengaged until the system is reset on the ground.
Originally Posted by alogobotur
Thx for the AP answers. So, AP switching on was not an option at all. It was also technicaly impossible.
Of course, once aeroplane was stalled, turning on the AP was impossible and pretty pointless.
Originally Posted by alogobotur
I want to hear something from the people who are also pilots, to hear what were they PROBABLY think
Originally Posted by alogbotur
After that they were "mad" and try to put the nose down, as I understand.
Originally Posted by Lonewolf50
jcjeant, being afflicted by fear or mental anguish is irrelevant if the problem was dying, don't you think?
Originally Posted by PuraVidaTransport
why with several nose-down inputs to the control stick, some lasting several seconds, why the elevators never moved into a nose-down position.
Originally Posted by PuraVidaTransport
. I've asked that question a couple of times and no one seems to know
Originally Posted by PuraVidaTransport
So even though the pilot commands nose-down, the fly-by-wire never moved the elevators to a nose-down position...for 15 seconds!!!
Originally Posted by PJ2
The fact that the other pilot cannot know what input is being made and therefore cannot make correct assessments as to aircraft handling is the reason why dual inputs are prohibited.
Originally Posted by alogobotur
They were obviously flying thru the storm, why they didn't go around it?
Originally Posted by BEA final report pages 168-169
But the aeroplane had not encountered, before or during the accident, an exceptional meteorological situation from the point of view of phenomena that are traditionally avoided in stormy environments (turbulence,lightning, icing).
Originally Posted by Lyman
At Court, to the Judge.
Originally Posted by DozyWannabe
The key detail is that they had no experience or training in high-altitude manual handling.
Originally Posted by Machinbird
But wasn't Bonin flying with his feet flat on the floor?
Originally Posted by Machinbird
You do a pretty good job, but sometimes you draw some strange conclusions----and I attribute that to lack of hands on experience.
Originally Posted by jcjeant
the company that employed the pilots felt that A330 does not require knowledge of manual flight at high altitude
Originally Posted by jcjeant
this is a potential catastrophe in the waiting ..
Originally Posted by Lyman
As if Pitch and AoA are unknown in aeronautics?
Originally Posted by CONF iture
Correct, but no pilot would accept to remain steady 3 or 400 ft below in RVSM airspace
Originally Posted by CONFiture
Some experiment has to be done.
Originally Posted by CONFiture
Why not correcting something that is stupid : auto trimming to the point of stall and further into it - Let a pilot take such deadly initiative, don't do it for him.
Perish the thought. Autotrim is just automatic trim. Any aeroplane, anywhere, anytime is properly flown with reference to attitude. Whether the residual stick force after the required performance is achieved is trimmed out manually or automatically is just a minor detail.
Originally Posted by gums
So the system will attempt to achieve 1 gee corrected for pitch attitude. Have I read that wrong?
Originally Posted by Lyman
This crew, but especially PF Bonin, was not madly pulling on the stick from the loss of A/P, not at all.
Originally Posted by DozyWannabe
Commanding a pitch attitude with the stick will cause autotrim to maintain the pitch attitude at the point the stick was released to the best of its ability.
Originally Posted by PJ2
Airbus and the BEA must have thought so because they replicated AF447 and in the Final Report even drew graphs in comparison with AF447's flight data.
Originally Posted by PJ2
It is neither practically nor philosophically merely just an "iterative example of how technology has changed." It is a far more complex human phenomenon that requires the respect of awareness. Technology changes who we are and if we are blind to that, we are blind to its dangers while lauding its benefits.
Originally Posted by PJ2
You already know I have no problem with automation and all technological advances just so long as one knows one's craft and can do the job when the bytes and pixels quit
Originally Posted by PJ2
Understood, yes!, but never respected and that means knowing how to fly and think regardless of technology.
Originally Posted by PJ2
Now I never went back to manual trim airplanes so can't speak for that direction of a transition.
Originally Posted by gums
Gotta tellya, that if the AF447 crew had a gut understanding of the system, we wouldn't all be here talking about it.
Originally Posted by PJ2
Granted a 5deg pitch up at FL350 won't lead to stalling the airplane, but why destabilize the airplane in the first place?
Originally Posted by Mac the Knife
Wouldn't their Attitude Indicator showing a lot of blue sky given them a clue?
|
Clandestino
It might come as news to some that recorders are fitted to help advance aviation safety and are not intended to be used in connection with civil trials. Even using them in criminal cases is not something aviation authorities look favourably upon. However. "Intended" is the backstop for the righteous. Pragmatically, data is data, and is available to whomever can acquire it. You are a pilot. You by definition deal in reality, not moral judgment. Therefore.... Quote: Originally Posted by Lyman This crew, but especially PF Bonin, was not madly pulling on the stick from the loss of A/P, not at all. This accident happened in twenty seconds, not four minutes. That is my opinion, and always has been. Are you accusing BEA of forging the sidestick traces? PJ2 has posted, initially, "do nothing", which he has amended to mean, don't be precipitous, or ham handed, to which virtually all transport pilots agree. Pilot flying input NU and RL, as he should. His inputs to me reflected a residual memory of flying in NORMAL LAW, where his inputs would have been modulated. Big mistake, and perhaps one that caused the crash, at least partially. The next ten seconds show an acclimation to a new and degraded LAW, and an eventual settling of Roll. The PITCH axis remained in a mode that modulated his inputs, and this may have subconsciously affected his muscle memory, in that he was not sufficiently focused on PITCH. Ninety nine per cent of the posts in this and the other threads focus on the STALL, or the CLIMB, or the CAPTAIN. It has been established that no one knows what caused the CLIMB, except to hone in on, Pilot Error. That is fine by me. You? |
Howdy, Clanedstino, as usual your comments spice up our discussion. :ok:
A few points: ... have a look at the CM2 stick trace! That's made by a guy who believed he would die if he just lets go of the stick! Such accidents are with us ever since the aeroplanes were first stalled! True, but not very applicable to AF447, which was a case of pilots unable to remember and apply basic flying lessons at 4AM, which might be partly affected by not understanding how thin is the Airbus's technological armour shielding from the elements. Have a look at the pitch; it's not consistent with CM2 doing low level UAS drill at high level, but rather as if he were trying to run away at all costs from something he believed was coming from below to get him. Mac the Knife Wouldn't their Attitude Indicator showing a lot of blue sky given them a clue? They absorbed roll info all right but just couldn't connect the blue on AH and rapidly winding altimeter with idea they will eventually run out of speed and stall. EDIT: As to "what they were probably thinking" I will mildly disagree with you. a. Probably nothing at all. b. Control inputs and cockpit audio bear no trace of anything that suggest the presence of rationality. c. They were panic stricken. b. They indicate a crew behind the aircraft. There were reasons for some of what they did, hence a rational thought process, but those reasons seem to have been based on faulty diagnosis of their problem, faulty recall of procedures, and faulty flying skills, and faulty CRM technique. c. In the last minute, maybe so, but in the first three, confused more than panic stricken ... unless there's more to my guess about the pursuing harpy than my wisearse comment warrants! :} |
Are you accusing BEA of forging the sidestick traces? A330 has shown some eccentricities in Flight Control, to wit, uncommanded climb..... Suppose Air France flight 447 had been victim of these "eccentricities"? The "CLIMB" was instead a desperate attempt by Bonin to FORCE the nose DOWN, not hold it up? If 447 had been lost to Airbus, not BONIN, what then? Can you imagine? "AIRBUS kills 228 over the ATLANTIC" Boy Howdy. Until the boxes were found, who could say? Afterwards, and in the possession of an agency that had been accused of criminal conduct to protect the airframer prior, who could say "The pilot performed as expected in the CLIMB emergency, and all the way to the OCEAN"..."He tried the entire while to drop the nose, by pushing the Stick forward". Without ACCESS? In the possession of those who refuse to release all the DATA? It would seem a simple task, disclose. What would I do? Right Wrong or indifferent, I would do the same. Keep the "DATA" secret, and a passive non emotive expression.... Pragmatic. After ALL, they're all dead..... |
3holelover;
Have I understood the display correctly? It has never been my sense that an AoA indication somewhere on the forward panel or screen real estate would have made a difference to the AF447 outcome. As with the FPV, an AoA indication is part of the kit only when its information is understood within its context of high-altitude, high-speed swept-wing flight. Lonewolf_50; In Re the original quote,
Originally Posted by Clandestino
Quote: Originally Posted by Mac the Knife Wouldn't their Attitude Indicator showing a lot of blue sky given them a clue? The altitude and rate of climb would have been visible on both PFDs. Clandestino; Quote: Originally Posted by PJ2 Granted a 5deg pitch up at FL350 won't lead to stalling the airplane, but why destabilize the airplane in the first place? The data clearly indicates that in percentage time, the SS was in the NU position most of the time and the left and right elevators were entirely in the NU position throughout the descent: http://www.smugmug.com/photos/i-GRhj...GRhjsb6-X2.jpg PJ2 |
Originally Posted by Clandestino
(Post 7728597)
It's not a key detail but infrared herring. Issue is not handling but having no idea of the aeroplane's energy state. CM2 stalled aeroplane pretty deftly.
Not quite... it will maintain flightpath so left with nose-up, it will increase pitch as airspeed decays and alpha goes up. However, it is not as bad as some try to make it seem. Pilot needs to be quite incapacitated to leave the aeroplane wonder on her own.
Originally Posted by Lyman (re: falsifying recorder evidence)
(Post 7728809)
But if I wanted to, I would......
Hopefully this thread will shortly return to rest, 'cos there's nothing new being discussed here. |
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