On the weekend gig, I introduce the guest pilots to the notion of aerodynamic stall. Some of them get a gleam of fear in their eyes when they hear the word “stall”, because they invariably think it is ineluctably linked with “spin, crash and die.” Which can be true, but isn’t necessarily so: Learning how to stall and recover an airplane is one of the first things the novice aviator is taught, and it is re-learned in every aircraft transition.
When I brief my civvie passengers on weekend dogfight hops – that’s not a Michael Vick dance variation, by the way – I try to explain to them the relationship between stick position and angle-of-attack: “If you push the stick forward, the houses get bigger. If you pull stick aft, the houses get smaller. If you keep pulling aft on the stick, the houses start getting bigger again.”
Note to Air France: I’m available for consultative work.
Point.enquete.af447.27mai2011.En
I get that the weather was rough. I understand that the compound emergency and loss of normal displays was confusing. I suspect that in their peril, the pilots were left to wonder whether some strange software gremlin had suddenly rendered their aircraft un-flyable.
But – and this is not to beat a dead horse – I really don’t understand how no one among three very experienced and highly trained airline transport pilots ever figured out that it was worth a try to lower the nose and reduce the angle of attack. Maybe get some airflow over the wings.
Stall warnings coupled with wing rock are classic indications of deep stall, and if what you’re doing isn’t working it’s time to consider something else.
It does make you wonder at the background/training of Air France pilots. For a long time US commerical aviation has benefited from hiring former military aviators, and I wonder if that is not the case in Euroland.
I don’t know about Air France, but Lufthansa used to hire and train pilots in much the same manner as the Luftwaffe did. The major advantage of the military over most civilians is the experience of being immersed in your training with few distractions. The Air Force and Army did not permit any type of private flying, but would allow flight on scheduled airlines if you had to take a break in training and go somewhere.
Unless AF operates like Lufthansa, I’d beta dollar to a donut that a lot of their pilots were military pilots first. That doesn’t mean they can’t do something boneheaded from time to time, like not flying the AC, or trying something different if what you’ve been doing doesn’t work. I suspect information conflict and overload caused a brain freeze and caused them not to recognize a deep stall.
What was the motivation for disallowing private flying? I thought the more the merrier.
One of the points of military flying is the immersion aspect of it, and they didn’t want you playing around and forming bad habits, by their definition. Additionally, if you’re going to risk hide and hair, then they want to do it rather than let you have all the fun by yourself.
OK, that makes perfect sense.
It’s hard to understand how despite the loss of instrumentation the experienced pilots didn’t recognize that the wing was stalling; especially given the 20 degrees or so total roll change.
Maybe they couldn’t see a horizon to help them discern their angle of attack “by the seat of their pants”, but given their altitude you’d think they might have traded some altitude for airspeed, especially after the wing rock began…
I realize they are used to a full suite of electronic displays, but I wonder if they have a good ol’ artificial horizon to back them up? From the results, I guess not.
Shades of Colgan Air a while back. Same reaction, same disaster followed. Makes one wonder about the modern training world. Are electric cockpits and autothrottles robbing the transport world of stick and throttle skills? What is missing from the simulators today?
How can a transport be at 35,000′ and 15 degrees nose up without someone in the cockpit taking some serious emergency action?
Grandpa Pettibone: What were they thinking?
We’ll probably never know…
Does make you wonder that with good engines, 38,000 worth of “we ain’t hit yet”, I assume a GPS, and 3 guys with probably tens of thousands of hours that they couldn’t fly the aircraft. Before Pensacola my civvie flight instructor actually had you put on opaque glasses and you had to take the aircraft controls at altitude and fly just by sound and feel. Fairly easy to do straight and level in a 172, but once things got wrong for long they tended to diverge from right real quick. In an Airbus you obviously wouldn’t have the same direct stimuli.
A little more info,
http://flightlevel390.blogspot.com/
InBeforetheHeavyJetGuysChimeIn: This is from a similar discussion over on the Yahoo Stinson Owners Group. The writer is the son of one of my pilots. The son is an highly experienced GA, Experimental, warbird and Part 121 heavy equipment operator. This should add some insight:
[i]“I have something to add with regards to the stall recovery technique for large transport category aircraft. The stall recovery for small planes like our Stinsons and large planes like Boeings are very different. I flew the 747-200 and now just checked out on the 747-400. We do not push the nose down for a stall recovery. We apply max thrust and pitch to about 5 degrees nose up and power out of the stall. The goal is to lose as little altitude as possible. These stalls are practiced at 10K-18K ( in the sim of course ). Of course high altitude stalls would require a trade of altitude for airspeed. The funny thing is that we do not practice high altitude stalls.
We also have a procedure for flight with unreliable airspeed which boils down to pitch and power. We have a readily available chart that gives us the pitch/power for various weights and altitudes…
If you are stalling an airplane with 4 engines out on a 747 you have a more serious issue than stalling. You have no hydraulics therefore no control. You need to keep the airspeed above 160kts for the engines to windmill fast enough to power the flight controls.
All of our stall training is to the first indication of the stall (ie stick shaker). Like you said, that is before the wing actually stalls. We do approach stalls (landing configuration in a 20 degree bank) and clean stalls.
What I was getting at is what has been released that the Air France crew failed to push the nose over to recover from a stall and that goes against the training for stall recovery. I have never been taught to push to nose over to recover from a stall that way in the Boeing. The next time I am in the sim, I am going to ask the instructor to give me their scenario and try to recover from a stall at high altitude and then use pitch and power to keep the plane flying.”[/i]
Can you ask the 747 driver to explain the relevance of 4-engine failed stall recovery to this discussion?
AFAIK AF447 had power available on both engines throughout the episode.
Mitch,
That was in reference to forward speed versus descent speed, specifically as it applies to the Whale, I did not excerpt the rest of the lengthy discussion. There are a number of other US and foreign heavy drivers on the group, so they have gotten into some type-specific discussion as well as the overall talk about AF447. Interesting to note that they all are discussing that the next time they are in the sims, of doing AF447-type scenarios for their aircraft types.
There has to be a lot more to this than is yet known. These pilots were not rookies: Even the two more junior pilots had 6,500 and 2,900 hours respectively.
The Airbus is a very complex aircraft with many extremely computerized systems. It does not fly like “normal aircraft,” and it will sometimes do unexplained, strange things. One interesting point is:
If the pitch trim moved up to 13 degrees in less than a minute, why did that happen? It is an abnormal trim setting that the pilots did not set, and remained there until impact. There are times when the ever-present automation (even off autopilot) does what it wants to do even when it is in contradiction to what the pilot wants to do. But the pilot normally should be able to dial-down the forced automation.
Experience should be an indicator of sorts, but in this case no one recognized the extreme position they were in. Why? I can relate that once in my transport career an experienced DC-10 Captain put the airplane in a stall while holding at altitude. The immediate loud buffet (things can come off a big jet in that situation) only caused the Captain to ask “What’s that noise?” as the first officer (yours truly) pushed the throttles way up and lowered the nose to recover. That incident really got my attention. When people are caught by surprise the response isn’t related to experience if the event has never happened to them before. My response was immediate because of military experience, the buffet was the same as I remembered from ACM yanking and banking. The left seater was from a different environment and had no “template” in his mind to relate to.
Apparently the the trim is set automatically based on side stick position. The pilot flying had nose up input pretty much continuously through out the event. They got two stall warnings before the airspeed dropped below 60kts where AOA becomes invalid. They ballooned up to 38000′ where the PF put the nose forward and gained enough speed for the AOA to be valid again and got another stall warning. The PF pulled the nose up again. (Make the bad noise stop?). They aircraft was apparently relatively stable in the stall and maintained somewhere around 16 degrees pitch attitude all the way down. So once the PF had nose up input for an extended period of time the THS went to 13 degrees and stayed there. This is indicated on the manual trim wheel, but apparently manual trim is almost never used in the A330.
It’s really easy to shake our collective heads at the pilots actions after the fact, but lets look at a couple of factors:
1. It’s 0130 (plus a couple hours for time zone changes.)
2. You’re in the middle of the Atlantic Ocean
3. You’re in a thunderstorm.
4. You lose your pitot inputs due to icing, so the auto pilot says “I’m out of here!”
5. Your controls no longer work the way you’re used to. (Alternate law – I believe direct roll control and the software now works differently.)
6. You know that at your present attitude the difference between Vne and stall speed is not all that great. Did I mention you’re in a thunderstorm, at night?
7. A bunch of your instruments are no longer giving you valid indications. Which ones are giving you good indications?
So the plane feels relatively stable, you’ve got no airspeed indication, you don’t have a stall warning, and your rate of descent is somewhere around 11000 feet per minute.
Let me know how that works for you….
Seriously – a real training factor may be that bad things don’t happen very often in aviation any more, so a high time pilot may not have much experience with emergencies. Anyone who flies ought to read “Fate is the Hunter.” by Earnest Gann for a reminder of what pilots used to have to deal with.
There is an extremely detailed thread about this in Pprune. (Professional Pilots Rumor Network.)
And don’t forget they were in the midst of some pretty serious convective wx when confronted with the airspeed display issues. Might have made normal recovery technique a bit mre challenging.
I am no pilot (obviously)but I have spent quite a bit of time thinking about this story since I heard the news reports on the findings from this crash and the large amount of criticism from the flight experts/pilots that I’ve heard comment on it.
Granted, a plane crash is pretty much my number one on the list of ways I prefer NOT to die (I went flying in college with someone getting their pilots licence. Midway through they stalled the plane and pretended there was a problem with it. I seriously thought we were going to die. I’m a *very* uneasy flight passenger to this day.)but the way it went down seems especially horrifying and confusing to me.
I hope that if there IS more to this than we know they release the information because it seems to be puzzling everyone with any kind of flight experience. Obviously, the results could not have been worse.
“Midway through they stalled the plane and pretended there was a problem with it. I seriously thought we were going to die.”
I sincerely hope you beat him to death with his logbook once ground-side.
That certainly would have been my reaction, post-flight. He’d have permanently lost his medical after a stunt like that.
What is it about some guys, and their wrong ideas about how to impress women? Hell, I suspect myself of having autistic tendencies, and I know better than to do stuff like that. Of course, when I was that guy’s age…
He was just young and stupid. A condition that most of us on this thread have suffered at one time or other.
Funny, I have been in the back for numerous stalls to Shaker, Pusher and Aero-stalls. In RJ-200, -700, -900, GIV-X and G550 (not to mention Cessna 172s, 150s, Piper Arrows, Archers, Cherokees). Standard practice is to dump the nose(at least for the test pilot community). These pilots were trained by USAF, USN, Canadian Forces, and a couple of retired RAF types. PAX, Edwards and Empire.
Never saw Mr. 747′s technique.
A-B, apparently this is either a line-specific or type-specific technique. Although other heavy operators, mainly of Boeing products, all mention similar “approach-to-stall” recovery techniques.
Boy, you’re so right about that “mental template” bit Busbob. And btw, “SpeigalOnline” has a very good art. about the findings, pointing out that it would have been physically impossible for even BOTH pilots to push the nose over with the pitch trim stuck at 13 degrees–but even more significantly the art. states that resort to the physical trim wheel between the throttle quadrants was NOT on the company EMR check-list prior to the accident, but IS now.
See”Doomed Flight AF 447:Questions Raised about Airbus Automated Control System”@
http://www.spiegel.de/international/world/0,1518,765764,00.html
Fundamentally, the same problem reared its ugly head here…
Seems that the sirens are still out there
…nautical
and aero….
That grey matter between your ears still matters.
Perhaps we should ask how many hours they had hanging from their straps while spinning a T-2 inverted (or similar)? The lack of acrobatic and severely unusual attitude (tumbling) recovery training in heavies is likely a major cause.
Good point. A lot of pilots without military training have little to no exposure to unusual attitudes.
Thinking vectors in my head; would a 16-deg pitch-up coupled with a falling line that loses 30,000+ feet in two minutes create enough flat drag that the pilots’ inner ears would be telling them they were climbing?
Maybe it’s like they were balanced (& kept themselves balanced there thru nose-up and roll inputs) belly-down on the fall line; all their drag would have been felt as acceleration upward?
Like a flat spin without the spin; coming down like a shuttle through the upper atmo; belly down, nose high, g-vector aimed straight up through the floor.
Non-pilot speculation on my part. Would seem to require that both wings and elevator were stalled, though.
Not sure both would have been stalled if the nose up attitude was stable through the descent. The inner ear does often lie. On AFTV out of Ramstein they used to do a demo on what happens in a turn when the man has no outside reference to know his inner ear is lying to him (it was interesting what they used in place of commercials). I could see their inner ears telling them they were climbing and not falling.
One thing they may not have paid attention to was the increasing pressure on their ear drums. A cabin us usually kept at a pressure altitude of around 8,000 feet. Below that there would have been increasing pressure on the ear, and unless they equalized without thinking about it (and they may have), they should have noticed something. I do when I’m on an airline flight, but I’m just looking out the window, and not fighting an aircraft.
Having plenty of energy in hand, be it potential (from height or fuel) or kinetic (from speed) is always a Good Thing, as Martha Stewart might have said.
This is probably an odd question I am hoping Mr. Lex or those who have knowledge can answer.
The pitot tubes were frozen over or suspected to be frozen over. And in most(?) modern aircraft the displays are all computer driven with information from said tubes.
Would there be a way to install old style instruments that didn’t rely on this stuff? Like an additional set of instruments for emergency use when the computers go on strike? Is it feasible? Just wondering.
There are standby attitude, airspeed, and altimeter systems in most of the modern transport aircraft. They are not computer driven. A compromised pitot system may mean the standby airspeed indicator is faulty as well, leaving just the attitude indicator and the altimeter.
What would you do if someone who seriously disliked you stuck some chewing gum into the static port on your airplane?
Yep, there is an integrated standby instrument with its own pitot tube and static source. The ISI should have artificial horizon, Mach, airspeed and altitude.
With a three ADC ( Air data computer) system there will be airspeed, altitude, vertical speed and (if a Goodrich SmartProbe) Angle of attack (AoA or Alpha) and sideslip angle (beta). There should also be cross plumbing between opposite side systems.
Who certified an pitot probe with inadequate power(watts) for anti-ice? Smells like EASA B.S. for THALES. Pitot tubes should be heated from weight off wheels until touchdown or later. With a secondary pitot heat system available if the primary pitot heat fails. Static pressure plates should be heated also.
According to some of my instrumentation colleagues, this is basically an Airbus spec design flaw compared to Boeing spec. Boeing people are institutionally (and correctly) paranoid against icing. All drain holes must be numerous and of .XX diameter. For pitots, it’s two larger drain holes to Airbus’ one (note, this was just discussion, I have not seen the drawings). I think there are some institutional issues at work.
Aero, you might be more familiar with this, but are EASA standards not as strict when it comes to the environmental testing for certification? I would think that basic DO-160 stuff like icing would be covered in critical parts like this.
Well, they still would have lost airspeed indications if the pitot tubes had been frozen over. But if they’d been flying on steam gauges vice glass, and had to hand fly it vice let George and auto throttles drive the bus, they probably would have been able to maintain aircraft control. The downside is that we’d probably see more of the old school exhaustion/deviations so common in the “golden age” of flight, and over time we’d lose more jet liners. All of the gee-whiz stuff is pretty nice when it’s all working. No substitute for stick and rudder skills when it’s not.
There probably ought to be a requirement that modern airline pilots need 50 hours per year in a Stearman or Aeronca Champ just to keep them honest.
Reminds me of my F-150. Modern tech works just fine, until it doesn’t.
The below imagery is the one that always sticks with me regarding Airbus types, their `glass cockpits` and computers and stuff. Can’t recall the outcome of the enquiry other than something to do with a `puter. I’m keen to learn, though.
http://www.youtube.com/watch?v=-kHa3WNerjU&feature=related
I detect that the Champ taught you a thing or two….
Oh, they will. They will.
Aviate,Navigate, Communicate. Still works. Airbus tends to want to replace the pilot. Spare me engineers who try to outthink the pilot. No good shall come of this.
Yup. Engineers may know more than pilots, but they aren’t there, in the air.
The insinuation(and outright statements)in these comments that military trained pilots would have done better under still-to-be-determined- circumstances is silly. I’ve seen B-52, A-6, and F-4 pilots that frankly sucked flying 767′s and 747′s (including the yanking and banking part)…I just flew a trip with a former Marine F-18 driver whose performance required maximum embarrassment suppression from his fellow crewmembers on the way to the hotel…a friend of mine just flew with a retired Air Force Two Star at another carrier who was late showing up, had “systems issues”, and slept all the way to SFO. Of course, other military pilots are pure poetry in the cockpit and a privelege to fly with. There are good ones and bad ones.
Aero-Bracero…I don’t know “Mr 747″, but the explanation for his “technique” is actually THE procedure. One case is based on ground contact being a factor (low altitude)…power out of it. The other is based on ground contact NOT being a factor (high altitude)…trade altitude for control and speed. “From the back” colors your comment. Just “dump the nose” makes me laugh.
POGUE and BUSBOB…very thoughtful comments.
I vote YES on 50 hrs/yr Stearman training. More for fun than relevance…but still a YES vote. Expanded sim training–in type–is, of course, the answer to keeping us liars honest.
Mark, I work or have worked with TEST pilots at Lockheed, Learjet and Gulfstream. “Dump the nose” or lower the angle of attack is the technique to counteract a stall. Whether at altitude or in takeoff configuration at low altitude. Lower the aoa then add throttle( if you have any available) to get out of the stall and away from the stall (margin).
What’s wrong with from the back? I have observed a lot of pilots, granted, they were the top 5 or even 1% since they were TEST pilots.
Of course my comments are colored. Your’s certainly are.
How do you power out of a stall if your already in takeoff config? Gear down, Flaps 20, TOGA (takeoff Go around) power? Even if you are near the ground, you lower the nose (Angle of attack). Sounds like a line pilot. Good, continue to use the stall barrier system. We Flight Test Engineers (poor worthless souls who ride in the back of airplanes) and TEST Pilots did the envelope expansion so you didn’t have to.
Amen!
I am told by some who should know that the “newest Airbuses revert to Angle-of-Attack (AOA) when airspeed indication is lost.
But this aircraft did not have this latest and very simple modification. (It is called, “Back Up Speed Scale” (BUSS). (Why is it now implemented, so much later in the production line?) Had the crew had this simple AOA info, this accident should not have happened.
What were the inaccurate altitude/airspeed indications this crew received, combined with nasty weather (and in the dark?), the multiple ECAM and loud and confusing, Aural Warnings, the turbulence and buffet? Perhaps they were suddenly even in a spin without knowing it? What were the computerized, loud aural warnings and flashing warning lights telling them? And perhaps with faulty back-up instruments too? And vertigo? Were the controls mandated by the pilot, or by a computer? Did bad info lead one, the other, or both to screw it up, big time? I think one had to have been there to truly judge. This thing is a complex mass of multiple computers; it is not a Stearman.
Given the huge amount of money at stake, we will probably never know the whole truth. Nevertheless, the cheapest solution is always to blame pilot error. And all too often, some fellow eat-your-own pilots are usually the most eager critics.
Repeating a question asked in another post: Would having MECH or DEL flight control reversion modes, as in the FA-18, be a workable option to preclude Autopilot overriding the crew in failed sensor environments? Extending this back to the B-2 crash in Guam, and low altitude notwithstanding, might having such modes been enough for the crew to recover the aircraft?
Another concern comes to mind, stemming out of something I saw incorporated in the FA-18: spin recovery arrows in the HUD prompting the pilot to input rudder in the direction of the arrow (If I have it right), rather than require full focus by the pilot on his/her array of instruments. Extending that to more sophisticated systems in use today, are the computers trying to outsmart the pilots? ‘Face’ Kennedy once commented that a quite a number of young Aviators were getting lost due to increased dependence on systems, rather than using the basic navigation skills in the bone dome, and needed to get back to basic skills.
Opinions? Observations?
“Would having MECH or DEL flight control reversion modes, as in the FA-18, be a workable option to preclude Autopilot overriding the crew in failed sensor environments? Extending this back to the B-2 crash in Guam, and low altitude notwithstanding, might having such modes been enough for the crew to recover the aircraft?”
Reversion mode in an F/A-18 is one thing.
But in a B-2, quite another.
Let’s remind ourselves that Edwards AFB is named after a guy who found out that a flying wing with directly coupled flight controls was a lethal handful.
Relevance to an Airbus loss omitted. I do not think enough data have yet obtained to form definitive conclusions about AF447.
“I do not think enough data have yet obtained to form definitive conclusions about AF447.”
Mostly true…
But I think the lack of physical feedback in the flight controls can now be seen as a complicating factor in an emergency, as you had both flying pilots attempting simultaneous inputs.
“Anyone who flies ought to read “Fate is the Hunter.” by Earnest Gann for a reminder of what pilots used to have to deal with.”
We get a steady procession of soon to graduate Embry-Riddle kids…All on their way to getting their Commercial CFI Multi or already have it.
I have yet to meet one who has ever heard of Earnie Gann, or “Fate is the Hunter.”
Was talking to one recent grad just the other day. A fetching young lass working for a large firm you’d all recognize, said…”I don’t have time for all that old stuff. History drives me nuts.”
At the time we were in a room with a large print of a Trimotor on one wall, and a DC-7 sucking up its gear on another.
I just had to sigh and walk away.
Makes you wonder what a ~hundred thousand dollar education buys these days.
Sid,
Sounds like 90% of my fellow Naval Aviators and Naval Flight Officers. When you either are educated in an environment that sneers at history as a “lesser” discipline or where you can’t keep your ROTC scholarship with a BA degree, what do you expect?
“…or where you can’t keep you’re ROTC scholarship with a BA degree..”
Is that now true, Comjam? Of course I went thru AROTC (62-66) in the days when it was mandatory on many college campii (mine included) for the ENTIRE male student body for the 1st two years and there were no scholarships at all (except maybe NROTC on small campuses where ROTC was not mandetory, iirc–Tulane comes to mind) I grad. w. a BA–is this now verboten or just at some programs?
**AFROTC
It wasn’t back in ’77 in AFROTC. I knew a number of A grads who came though AFROTC back then.
I was referring to NROTC only; at one point I did applicant interviews, so I had to know the system. The four-year scholarships were for BS degrees only. Although I understand a number of young ROTC Mids changed their majors right after the beginning of their Junior college years with no repercussions, but that’s pure scuttlebutt.
That is one of my favorite books. I read it first when I was a kid. It was the book which taught me about The Mail Gun, the revolver which pilots were not forbidden, but _required_, to carry up until 1967 or so.
Some of them are packin’ again…
There are times I have to ride jumpseat. A brief with an FFDO goes, “Better duck or I will shot through you.” Of course, strapped as I am to a shelf on the door on at least certain types of aircraft, I kinda figure I’m fodder anyway.
Oh.
And to be fair to that young recent Embry-Riddle grad… Later, she did ask me the name of the book and author again. I may see her again in September, so will ask if she has read it yet.
JTG, had the pleasure of having EKG as out guest speaker at a Dining In while at Whidbey. He had retired on one of the San Juan islands. His remarks were every bit as good as his books.
I envy you that experience XAB.
FITH is the first book about aviation, and the first one by Mr. Gann, that I can remember reading. I probably read it only a year or two after he wrote it in 1961.
A most memorable book.
“I don’t have time for all that old stuff. History drives me nuts.”
Face-palm time, sid, face-palm time..
There’s an interesting book on the interface between the humans and the automation in safety-critical systems–aircraft, nautical, and medical–focusing of course on cases where accidents happened because of interface problems. “Taming HAL”, by Asaf Degani.
Latest from the leadership at the Mighty Fortress is AF and NROTC are only interested in hard science or engineering majors.
Glad I escaped with my BA English while the gittn’ was good. I will promise, over my twenty seven years, I used my writing and researching skills much more often than my hard science or engineering peers used their undergrad skills. Sad.
It should but I do not trust EASA to hold a european manufacturer to the same effective standard as an american manufacturer. Additionally, the recommendation to change probes as opposed to a mandatory AD. EASA is a pain.
Sorry Scott, that was meant for GeoSTI.
To your point,do pilots really need a college degree??? I don’t think the IDF requires a BA/BS for flight school. NAVCADs weren’t required a degree, Army Warrant officers don’t have to either. I will bet we lose some gifted pilots as a result of the Math/Science/engineering requirement. ( I am a BS & MS Aerospace Engineer). I can understand the Math/Science/Engineering requirement for Test Pilot School, but one of the better TPS grads I have flown with was an army warrant officer with a Embry Riddle degree in Aviation Science.
Well said Fliterman…
I do not get the (sometimes)rather cavalier Monday morning quarterbacking. Disappointing from those with experience…
Aero-Bracero…To answer your question regarding your scenario: Start by reducing drag (raise the landing gear). Yes, you indeed may have to reduce the AOA (better choice of words). If you “dump the nose” (your words) or it is a full stall close to the ground (likely windshear?)…you likely lose the game. Your original comments seemed skeptical of someone passing good information (“Mr 747″)…and your choice of words seems simplistic “just dump the nose” reference a rather complex situation for the unfortunate Air France Crew. I did not knock flight test or engineers (despite your sarcasm and false self-deprecation)…just your simple characterization and inference.
As for your line pilot comment…get back to me when you have stalled something more than your car.
I have stalled some R/C airplanes, but when I was allowed to fly airplanes in which I was riding, the other guy always seemed to disapprove of my approaching a stalling condition. It was like they didn’t trust me, or something. Hell, we were up good and high, and all.
I don’t stall the bigger iron yet, we have well qualified guys to do that. They don’t do much analysis though. Your a touch sensitive, Mark. Too bad.
Line guys apparently are taught different techniques from TPS guys. If you would care to argue against aerodynamics, find a concrete wall. I am through with you.
I’m agreeing with aerobracero here. I’ve done stall techniques, but I’m primarily an engineer. No I haven’t flown heavies, but I have stalled a 737-8 in a simulator.
Now, I’m not be a pilot, but let’s see if this engineer can figure out why you “power out a stall” on a 747… Could it be that if you lower the nose in a plane with wings like a 747, you actually cut the lift generated. That’s because the 747 wings are maximized for lift when the nose is up, and when you lower the AOA over the wings, you can actually cut all lift? But then, there is the rub. If you lose forward thrust (say, engines out), then it doesn’t matter what the AOA over the wings are; becuase you have no AOA to speak of. At that point, lowering the nose will at least cause air to flow over the wings until you reach a point where you can increase AOA again. My understanding is AF447 had minutes to make this occur.
As aerobracero points out, you probably never had to get to the point of lowering the nose to recover a 747, because engineers like him put in the envelope for you to use the “power out” technique. I stongly suggest you quite looking at Stearman’s as entertainment and quit thinking the simulator is the best place to learn. Otherwise, us engineers might have to remind you the limitations of the simulators that we don’t always share when selling them.
[I'm not an Airbus pilot, but I do have a very old Aerospace Engineering degree and am a priority Holiday Inn Express member. What follows is my speculation.]
It’s worth noting that the incident airplane went in to ‘alternate law’ mode, which essentially makes the Airbus control stick into a regular airplane stick.
Thus a full aft pull on the stick does not result in the airplane raising its nose to a safe limit just shy of stalling AOA, instead it lets the pilot stall the airplane. A full left command in normal law limits roll to a safe roll rate and bank angle. These limits are removed in alternate law.
So holding the stick back and to the left in alternate law for 35 seconds was not a good plan.
Unless there is a physical limit on the system, it is still possible to “blow through” the shaker and pusher limits with a high angle of attack rate (alpha dot). (Assuming it has a stick shaker and pusher system). Given the tail configuration of the A-330 (conventional), I think you can lower the nose and get out of a stall. Not true of T-tail aircraft, where the tail gets blanked at high AOA. Hence spin chutes on X-ticket T-tails. Later.
‘Unless there is a physical limit on the system’.
The Airbus stick and rudder pedals are just connected to the computer. In normal law I’m pretty certain that you can’t ‘blow through’ what the computer considers safe limits for pitch, roll, or yaw rates.
In alternate law there just aren’t many limits.
True. Not many limits in alternate law. But the computer will still initiate a nose up command in alternate law if Vmo/Mmo is exceeded. A friend offered this interesting speculation.
“Pitot ices up in climb, indicated speed / Mach close to Vmo / Mmo, and pilots notice unreliable airspeed indications. Pilots react and use procedure for pitch/power. Blocked pitot caused increase in airspeed indications. Aircraft automation sees the aircraft exceeding Vmo / Mmo and pitch is automatically increased, aircraft climbs faster – increasing airspeed. Negative feedback loop.”
While the pilot might have been able to override this, he also might have been too late to accurately recognize or override.
Just one of very many speculations. With the Airbus, what you see is not always what you get, and sometimes it is debatable whether the computer or the pilot is actually doing the flying.
Airbus Flight Control Laws
I hate to fly. I hate to fly. Did I mention I hate to fly?
I’m the wife of a very experienced pilot, daughter of a very experienced pilot. Never step into an airplane unless necessary. But even I would have known to lower the nose in this situation. Basic physics. What happened is a mystery to me.
Flit…what would be the logic, in alternate law, of the computer protecting you from overspeed by raising the nose but *not* protecting you from stall by preventing you from raising the nose too much?
Just wanted to give some official Airbus data on stalls and their handling published in January 2011 in its safety magazine. Here is this link.
Et, bienvenue ami.
It might have those poor guys if only one of them at time was actuating the joystick.
I wonder what Airbus does with conflicting joystick inputs in alternate law. Average the inputs? Ignore one? Do nothing and just ignore the pathetic humans?
A good insider’s analysis and commentary regarding Air France 447 that has been making the rounds.
Letter of the Week: Airbuses Fly “Like a Video Game”
And the following Podcast
Thanks, flit–VERY interesting stuff.