OT: If it Ain't Boeing, I Ain't Going

[+Julhelm 266]

We didn't deal with that part of the envelope because you weren't ever expected to GET there.

That makes little sense - Isn't the whole point of training to prepare you for dealing with emergencies like that? Anyone who has a drivers license will have trained to recognize the onset of loss of traction, but also on how to recover the spin when it happens, even if you are not "expected to get there".

[FastCargo 412]

That makes little sense - Isn't the whole point of training to prepare you for dealing with emergencies like that? Anyone who has a drivers license will have trained to recognize the onset of loss of traction, but also on how to recover the spin when it happens, even if you are not "expected to get there".

 

Well, in theory, you shouldn't ever get that deep into a stall. Multiple protections are in place on modern airliners to prevent this sort of thing.

 

Then again, it shouldn't be possible to lose all 3 hydraulic systems on an A300 or DC-10 with a single point failure either...oh wait....

 

http://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_shootdown_incident

 

http://en.wikipedia.org/wiki/United_Airlines_Flight_232

 

Aviation is a constantly evolving field, where what we think we've learned something, only for unexpected problems to cause revisions. We've seen problems where under-automation has caused crew fatigue and overload, but over-automation has caused complacency and overload at the wrong time.

 

Thankfully, airlines (including mine) have started scenario training for unusual aircraft situations that you shouldn't normally get into, including full stall recovery, excessive aircraft attitudes, and flight with inoperative controls. Our airline has also started to encourage more 'hand flying' in certain regimes of flight to help keep the aircrews more involved in the process.

 

FC

[Bullethead 12]

In normal operations with airliners (Boeing, Airbus, McDonnell, etc), when the autopilot is on, the aircraft is not flown with the stick, it is usually flown with the control panel. You dial in altitudes, headings, speeds, etc, either through the upfront panel or through the Flight Management System (FMS) and the aircraft goes there. You do not touch the stick or throttles.

 

When you start moving the stick past a certain range, with the autopilot engaged, the autopilot will click off.

 

Well, you fly the things and I don't, so I bow to your superior knowledge. But I'm going by what other pilots I've known have told me, what I've read elsewhere, and what this PM article said. In fact, here's a quote from the PM article (March 2012, page 23):

 

"The vast majority of the time, the computer operates within what's known as normal law, which means that the computer will not enact any control movements that would cause the plane to leave its flight envelope. The flight control computer, under normal law, will not allow an aircraft to stall, (my emphasis) aviation experts say.

 

"But onces AF447's computer had lost its airspeed data, it disconnected the autopilot and switched from normal law to alternate law, a regime with far fewer restrictions on what a pilot can do. Bonin may have assumed that the stall warning was spurious because he didn't realize that the plane had removed its own restrictions against stalling." (my emphasis)

 

So what other conclusion can one draw from this (and this isn't the only place I've read or been told this) except that the control system, when fully operating, damps out the pilot's inputs into acceptable parameters? IOW, moving the stick isn't flying the plane, it's just suggesting to it that you want to go in a given direction, so the plane will fly itself that way.

 

I dunno. You fly the things and I don't, but I've heard the above many times before. So either there's a lot of misinformation out there, or there are different software versions available, one for actual pilots and 1 for people who can't fly.

 

As they say in Monty Python: 'No one expects to be less than 100 knots airborne in an airliner!'

 

Sure. But really, why do you even need to know what your airspeed is, or even your AOA? If you've got full power (known) and full back stick (known to Bonin at least) and the airplane is still descending rapidly (known), then either you're stalled or have suffered fatal damage that you can't fix. So your only option is to treat it as a stall and worry about how it happened later, if you get the chance. To me, that's flight dynamics 101, which anybody who calls himself a pilot should know.

 

OK, they lost ASI at the get-go so I can understand them not trusting it later, when it came back on prior to entering the fatal stall. But as I said above, I don't think knowing your airspeed is vital to the situation. And maybe they didn't have an AOA indicator (except they did, given Captain Dubois' last words "10 degrees pitch"). But they never lost VVI and the engines and their instruments always worked, and Bonin at least knew where the stick was. And Bonin knew what he was doing wasn't working, which is why he said he didn't have control. But he didn't have any other ideas.

 

This is what bothers me. It indicatates a lack of understanding of the fundamentals of flight itself. That's a much deeper training issue than merely introducing a different way to react to a stall situation. It seems to me that this Bonin guy, despite his thousands of hours, really didn't know how to fly, or even understand basic flight theory. He was just a collection of situational reactions without any understanding of the underlying processes. Thus, I can't avoid the conclusion that he was allowed to hold down his job because somewhere along the line, the powers that be deemed that pilots didn't need to know the fundamentals, given a flight control system that took care of all that. After all, the whole idea was to capture the market amongst developing nations.

 

Where automation gets pilots in trouble is when you use it as a crutch to get you to 100%. That is not the way it is to be used. Its true purpose is to keep you from getting fatigued, so that you are 100% when the time comes that you need to be.

 

I think that's how it should be. But I also think the Airbus philosophy is that the pilots exist to get the automation to 100%.

[FastCargo 412]

"The vast majority of the time, the computer operates within what's known as normal law, which means that the computer will not enact any control movements that would cause the plane to leave its flight envelope. The flight control computer, under normal law, will not allow an aircraft to stall, (my emphasis) aviation experts say.

 

"But onces AF447's computer had lost its airspeed data, it disconnected the autopilot and switched from normal law to alternate law, a regime with far fewer restrictions on what a pilot can do. Bonin may have assumed that the stall warning was spurious because he didn't realize that the plane had removed its own restrictions against stalling." (my emphasis)

 

So what other conclusion can one draw from this (and this isn't the only place I've read or been told this) except that the control system, when fully operating, damps out the pilot's inputs into acceptable parameters? IOW, moving the stick isn't flying the plane, it's just suggesting to it that you want to go in a given direction, so the plane will fly itself that way.

 

I dunno. You fly the things and I don't, but I've heard the above many times before. So either there's a lot of misinformation out there, or there are different software versions available, one for actual pilots and 1 for people who can't fly.[/font]

 

No. Just because the flight control system in Normal Law mode won't let you exceed its parameters doesn't mean you can't ham-hand the aircraft. What I keep interpreting from what you are saying is that the pilot can sit there and slam the stick to the stops and the jet will react like you're carrying passengers who don't want to spill their wine (the preferred way of flying). That is most definitely not true...if you are rough with the stick, you will be rough with the aircraft. The actual parameters of Normal Law are quite wide and will allow you fly well outside of what's considered efficient and effective handling. The short of it is...you still have to handle the aircraft gently and proficiently in your normal operations.

 

Sure. But really, why do you even need to know what your airspeed is, or even your AOA? If you've got full power (known) and full back stick (known to Bonin at least) and the airplane is still descending rapidly (known), then either you're stalled or have suffered fatal damage that you can't fix. So your only option is to treat it as a stall and worry about how it happened later, if you get the chance. To me, that's flight dynamics 101, which anybody who calls himself a pilot should know.

 

Actually, you can have a situation where this occurs...windshear. You can have a situation where you are darn near full back stick, throttles to the stops, airspeed going up and down in extreme amounts, and yes, be descending. We train for this in the sim, and its Mr. Toads wild ride because the aircraft is bucking, the bells and whisles are going off, you're trying to get the nose somewhere near 20 degrees nose up, and the engines are screaming. This actually will be relevant later...

 

OK, they lost ASI at the get-go so I can understand them not trusting it later, when it came back on prior to entering the fatal stall. But as I said above, I don't think knowing your airspeed is vital to the situation. And maybe they didn't have an AOA indicator (except they did, given Captain Dubois' last words "10 degrees pitch").

 

Airspeed is vital to the situation...note I talk about windshear training. One of things the pilot monitoring does is bring up the flight path vector in the case of a windshear alert. This FPV looks exactly like what you would see in a modern fighter's HUD...a little circle with 3 lines representing the aircraft. It gives you instant SA as to where the flight path is in reference to the nose position...AOA. Pitch is NOT AOA. Pitch is nose position relative to the horizon...AOA is nose position relative to flight path.

 

 

You could have a negative pitch angle, and still have positive AOA.

 

 

See the point here? '10 degrees pitch' is nice to know...but AOA would have been MUCH more useful

 

But they never lost VVI and the engines and their instruments always worked, and Bonin at least knew where the stick was. And Bonin knew what he was doing wasn't working, which is why he said he didn't have control. But he didn't have any other ideas.

 

This is what bothers me. It indicatates a lack of understanding of the fundamentals of flight itself. That's a much deeper training issue than merely introducing a different way to react to a stall situation. It seems to me that this Bonin guy, despite his thousands of hours, really didn't know how to fly, or even understand basic flight theory. He was just a collection of situational reactions without any understanding of the underlying processes. Thus, I can't avoid the conclusion that he was allowed to hold down his job because somewhere along the line, the powers that be deemed that pilots didn't need to know the fundamentals, given a flight control system that took care of all that. After all, the whole idea was to capture the market amongst developing nations.

 

And your conclusions are flawed. You are making an assumption sitting here at zero airspeed, zero altitude that somehow, somebody just instantly forgot all the lessons he learned because the Airbus trained and drained it out of him. You weren't there, in the middle of the night, weather all around, aircraft buffeting, airspeed unreliable, seeing a massive descent that you can't explain right off the top of your head...that somehow, you know that you wouldn't have let that happen to you...that you would have reacted better. That 'it can't happen to me'.

 

Bulls**t. The worse pilots I know were the ones who said 'it can't happen to me'. I typically say 'were' because a lot of them were either busted out...or are dead due to their own hubris.

 

As a Human Factors major, I have studied aircraft accidents, not just to learn how to avoid them, but what causes them...especially the ones where a perfectly good aircraft was crashed. Some are still head scratchers, even today, but most others, once I see and envision the situation, I can see where someone could be led down that path due to various factors. The better pilots I know are the ones who look at those situations, figure how it could happen to them, then take active steps to make sure it doesn't.

 

And lets have a little fun shall we? Your argument is that by taking more authority away from the pilot, that an Airbus (or similar advanced aircraft) is more vulnerable to pilot errors due to complacency.

 

If that's true...why do gear up landings continue to happen? Shouldn't we be seeing a rash of gear up landings in the Airbus...because after all it sucks out basic pilot skills. And putting the landing gear down is a pretty basic skill there. And in fact, shouldn't there be LESS inadvertent gear up landings in aircraft without hard limits? I'm not talking mechanical failure here...I'm talking the pilots just plain forgot to lower perfectly good landing hear on a perfectly good aircraft?

 

Yet, check this out in a Cessna, with a pilot who has thousands of hours:

 

 

Or this incident to a Eurofighter Pilot:

 

http://www.indiandefence.com/forums/f17/eurofighter-typhoon-4731/index19.html#post139832

 

Or this whoopsie:

 

 

And this one personally hurts to see:

 

 

There are stories and incidents from all across the spectrum and airframes of pilots needing full power to taxi after a landing. Why is that? Could it be an error not related to aircraft design? That fully experienced crews who should know better make a mistake? Even when there are multiple procedures and automation in place to prevent such a mistake? That it's a problem almost as old as the retractable landing gear aircraft that we still haven't completely fixed?

 

Pilots, even experienced, good aircrews, make mistakes. And depending on the timing...it may be the wrong one on the wrong day.

 

I think that's how it should be. But I also think the Airbus philosophy is that the pilots exist to get the automation to 100%.

 

And I disagree. You are making a crass generalization based on your bias against Airbus. And you're pretty smart...I've seen you post. You know better.

 

FC

[Bullethead 12]

And I disagree. You are making a crass generalization based on your bias against Airbus. And you're pretty smart...I've seen you post. You know better.

 

OK, you've convinced me.

 

I do feel the need to explain why I've thought otherwise, however.....

 

I'm not smart, I just read a lot. I rely on the writings of others, who are presumably more knowledgeable than myself, to learn about all subjects outside my personal experience. I've always thought this was the purpose of the written word.

 

Within my personal experience is a degree in industrial engineering, the majority of which is human factors. I'm also an officer in a fire department and have spent most of my working hours for the past dozen years training for, participating in, and debriefing extremely chaotic emergencies. So I do know a little about how people react and make decisions in highly stressful situations.

 

I have developed a bias against Airbus because I have read many articles that have said the same thing as the PM article I just quoted above: that under normal law, the Airbus won't "spill the wine" regardless of what the pilot does. I have read this and heard it from a few pilot friends enough times over the years, without ever seeing it contradicted, to come to believe this is true. And given what I think I know about human behavior under stress, I have formed a very low opinion of the level of training of pilots using this system. But what else was I supposed to think?

 

You are the 1st person in my experience to challenge this opinion. You have personal experience and firm belief in what you're saying. So you've convinced me that I'm laboring under a false impression. I will now change my opinion of Airbus and its related training levels.

 

This begs the question, however: if none of what I believed about Airbus is really true, then where did all the misinformation out there come from? It's so widespread, at least from where I sit, that it's either a vast conspiracy (which I don't believe in) or most people who write about Airbus for the lay audience don't know any more about it than I do (which is calls all other writings on technical issues into question). Or could there be different versions of the software available, the one you're familiar with and another that really "won't spill the wine"?

 

Anyway, you win.

 

[Herr Prop-Wasche 7]

Fascinating discussion, gentlemen. Thank you for sharing your thoughts on this incident.

[Pips 5]

Reading the above account simply horrifies me. 5,000+ hours and the crew couldn't even read an altimeter to see that they were falling out of the sky? Forget AOA, thrust or airspeed. Look at the Bloody Altimeter!!! Push the damn stick forward!

 

It's so basic, as everyone has mentioned. Words fail me.

 

Bullethead, was there anything in the article to give hope that Air France, or any air govening body, was taking steps to improve flight crew training to avoid such mistakes in the future?

Edited February 20, 2012 by Pips

[Bullethead 12]

Reading the above account simply horrifies me. 5,000+ hours and the crew couldn't even read an altimeter to see that they were falling out of the sky? Forget AOA, thrust or airspeed. Look at the Bloody Altimeter!!! Push the damn stick forward!

 

Yuppers. This is one of the points I was trying to make above but obviously didn't express very well. It was beaten into me early and often, both in training and through experience, that whenever you're in a time-sensitive situation, if what you're doing ain't working, you need to go to Plan B, C, D, or whatever you're up to by that point. This is a universal rule applicable to everything where you've only got a limited number of attempts at getting it right before you're hosed. This includes not only stressful things like combat and emergencies of all kinds, but also such things as convincing people to your POV (seduction, getting a promotion, persuading a jury, winning an argument), and artistic things like knapping flint, sculpture, etc. Reinforce success, never failure.

 

Bonin at least never learned this lesson in all his life prior to flying and then in his 5000+ hours. He was stuck in this loop:

• Airplane is going down
• Remedy for airplane going down is pulling back on stick and full power
• Airplane is still going down anyway
• Because airplane is still going down despite me efforts, I must not have any control over it, but I'll keep pulling back on stick anyway in hopes things change, and if somebody does anything different from me pulling the stick back, I'll cut them off and keep pulling the stick back

So regardless of whether the Airbus flight control system will "spill the wine" or not, to me this is still a much deeper training issue than merely learning another techique to avoid and/or recover from a stall.

Bullethead, was there anything in the article to give hope that Air France, or any air govening body, was taking steps to improve flight crew training to avoid such mistakes in the future?

 

I have no idea. The full transcript and commentary were published in late 2011 by Jean-Pierre Otelli in Erruers de Pilotage: Tome 5. It apparently caused a great outcry in France. But given the heavy government involvement, I'm not optimistic that there will be anything more than cosmetic "feel good" changes. Anytime a government is major player in something bad, that's all you ever get.

 

 

 

 

 

[FastCargo 412]

Look guys...none of us were there, and ultimately, we don't know WHY they continued to hold the stick back. I guarantee he was looking at the altitude...that's why the stick was back in the first place...but ultimately did not change the plan to adapt to the situation.

 

Bullethead was making the point that the problem is the aircraft and the method used to operate the aircraft due to its control laws. My point was that the aircraft does have hard control limits, but still can be tossed around within those limits, and therefore cannot be slammed to the stops like a 4 year old at an arcade game...see here:

 

http://www.airbusdriver.net/airbus_fltlaws.htm

 

Note the limits mentioned, and the limits not mentioned in Normal Law. The latitude is pretty wide (can you imagine 67 degrees of bank in an airliner?). But there are no mention of limits for passenger comfort. And the reason is pretty simple.

 

There are times when operating an aircraft that you need quick response. One of the most common times is landing in a high crosswind, especially due to gusts. You have to be able to rate the aircraft in quick bursts to counter gusty winds (which seem to be common in high crosswinds at some airports). You can't do that and not cause passenger discomfort...ie spilling the wine. Other situations that are less common include windshear, GPWS alerts, threat avoidance. I don't mention TCAS because for the most part, it allows itself enough warning for relatively mild changes to flightpath to deconflict. All those situations may require high rates of change outside of your typical airliner manuvering, but well within Normal Law limits.

 

So, it simply means you can't be 'ham hands' on a side-stick Airbus and expect to fly the aircraft reasonably...it will respond, while still staying within Normal Law limits. You'll look like an idiot, get busted on your checkride, probably cause passenger injury, and NO ONE will fly with you.

 

The reason people think that the aircraft is 'HAL' is simply because of the hard limits. The idea that a passenger airliner ultimately has final say so on what it will do with a pilot command is abhorrent to many pilots, and so all sorts of misconceptions get perpetuated based on that fact. Myths often start out with a grain of truth, and then take a life of their own.

 

As I have said before, I know many pilots on both sides of the issue who will argue tooth and nail why their viewpoint is right. These are guys with plenty of hours, could have their choice of aircraft, have faced their share of adversity and navigated it successfully.

 

Each accident must be judged on its own. My opinion is that the aircraft and its control laws are not the primary issue for this accident...otherwise we'd have Airbus accidents all over the place. Instead, we still see accidents across all ranges and airframes. Also, for those who don't know, check this out:

 

http://planecrashinfo.com/cause.htm

 

Note the table up top...pilot error is still at roughly 50% of all commerical airliner crashes for the last 50 years...dipped a little in the 70s and 80s, rose a little in the 90s and 00s. The scary thing about this table is some yokel could argue "Well, if you just took the human out of the loop, we'd have 50% less crashes...". Anyway, what I'm trying to say is that the statistic really hasn't changed in the last 50 years, even though we've been through several generations of airliners.

 

I think the thing everyone (including myself) should take away from this discussion is to avoid non-critical thinking. Very rarely is any situation completely black and white ("Oh, it's the aircraft's fault!?" or "The pilot was a dumbass!")...the reality is usually more complex than that. We have to learn to avoid our own biases...I had to dodge mine because I don't like the Airbus control laws. I think the idea that the aircraft has the ultimate final say so to be distasteful.

 

I have opinions as to what the pilots were thinking and why they reacted the way they did, and if I were king, what I would change about airline training to increase safety without decreasing productivity.

 

But that's not the point of the thread.

 

FC

[Flyby PC 23]

All I can add is being confused and bewildered screws up rational thoughts, especially when you don't know which way is up. If you see something bizarre on an instrument, you either trust it and forget the bizarre side of what you see, or you accept it is bizarre and inexplicable and naturally assume the instrument may be dysfunctional. There's only one way to find out which decision is correct.

 

I'm no pilot, but I have done some scuba dives in green pea soup while denied all sensory data. I didn't know what way was up, I couldn't even see my own bubbles, and I couldn't tell if I was sinking or rising or drifting in a current. Very unpleasant, I wanted to spew my guts, but at least I wasn't in an aircraft hurtling towards earth at the time. All that saved me was some of the green gloop looked half a tint lighter than the rest, and that way shone the sun. When it comes to the crunch, your survival instinct will trump any and all conflicting data.

[FastCargo 412]

That is always the issue when you encounter something outside your experience...you tend to fallback to make it look familiar, or to react in a way that is familiar to you.

 

Which may be totally the wrong thing to do.

 

Your story is a great example of when instinct can totally overcome rational thought.. Here's a harrowing HUD video of a spatial disorientation incident in an F-16:

 

 

The setup was a F-16 student on the wing, at night, in the weather. He goes 'lost wingman' (where the idea is to separate in a controlled manner from the formation lead if you lose sight), turns his head forward...and immediately gets disoriented because his vestibular organs have been in the wrong orientation due to looking sideways at lead.

 

Note here he KNOWS he's disoriented, he knows what to do, but he physically can't make his body listen to the rational part of his mind to straighten up the aircraft or get on the 'round dials'. He finally manages to inform lead, who is very coolly and firmly able to break through the student's disorientation to get him on the 'round dials'. I've been in that situation of being disoriented while being on the wing in the weather...and it takes a LOT of effort to convince yourself you're not in some ungodly bank angle and lead really isn't trying to fly you into the ground.

 

FC

[FastCargo 412]

This topic has been very interesting...I'm moving it to the general aviation part of the forum. I'll keep the original link here in the OFF section for folks still interested in following it.

 

FC

[Gr.Viper 131]

Fascinating. After reading all this, flying a piston engine helicopter under VFR feels like true heaven...

Well, OK, the list of collidable birds includes folks doing powered paragliding. And the rain can flood the pitot tube. And the slip indicator can leak, though two bits of string serve as a perfect backup. And the cockpit heater can pump the pit with CO. Still, it's bloody flying. Airliner control seems like flying a drone with your office inside it.

 

Would it be possible to design an airliner with An-2 stall characteristics?

[MigBuster 2,861]

Picked up a study called PILOT ERRORS INVOLVING HEAD-UP DISPLAYS (HUDs),HELMET-MOUNTED DISPLAYS (HMDs), AND NIGHT VISION GOGGLES (NVGs)(IDA PAPER P-2638) - which is study into pilot errors including spatial disorientation - and it goes into a lot about how the human brain is not so good interpreting digital displays - particularly HUDs and it thinks analogue dials are far better - which may explain why glass (tft) cockpits today have a lot of analogue dial representations - and that bloke in the F-16 vid is telling the pilot to look at the primary dials.

 

 

Making stupid mistakes is part of being human - hands up who has left the gear up in flight sims under no preasure (even after the radio tells you to check gear). I'm still not convinced the gears down sometimes 8 seconds after pressing G (admittedly in SF most pits don't have the gear lights).

[Toryu 156]

The issue s not so much as to why they never recovered from the 35-60°AoA, but why they'd get in there in the first place.

I can at least understand the disorientation of those pilots, with alle the conflicting messages (stick forward - stall warning starts, stick aft - stall warning stops!). Remember, they had a dark night with lots of weather around, operating at the worst time for brain-performance (the early morning hours of their "biological-watch" day) and just a couple of minutes after crew-rotation.

 

 

What really is hard to understand, why the PF (pilot flying) initiated at 7000fpm climb after the loss of airspeed-data. And this only a couple of minutes after clearly reading-out (before or during the handover-briefing) that the planned step-climb to FL370 would not be availiable due to themperature @alt.

 

What happened then is a zoom-climb to FL380, running out of airspeed and stalling, while the THS (Trimmable Horizintal Stabilizer) slowly went into the (almosst) full nose-up position. That trim-movement was COMMANDED by the crew (continously holding aft stick).

 

It actually is quire remarkable that the plane stayed "upright" in the following descend (L/D of about 1!), despite the tremendous AoA (never less than 35°!). By then, the spedd-data had already become valid again!

The problem, however, was that due to the AoA involved, the data of the pitots was inaccurate and giving-out an IAS of below 60KIAS. This in turn made the AoA-data invalid and led to the confusing stall-warnings.

This data-invalidation is, however, not a problem asociated to Airbuses exclusively - the B777 and B787 have a similar logic.

 

+x+x+x+

 

Now concerning the "spilling the wine"-story:

Those Normal-Law constraints aren't there for the designers' amusement.

The 67° bank- and -15°/+30° pitch-limitations are far beyond anything any pilot would ever do in PAX-service.

There are a couple of other protections (high AoA, low energy, "ground-speed mini" for windshear-recovery, etc) that have been designed into the aircraft for specific scenerios (CFIT avoidal is an example), not to take the pilot out of the loop.

The aircraft has been designed that way in order to give the pilots a handy tool in case they need to concentrate on a couple of things at once (say an engine-out TOGA go-around with terrain-avoidance).

 

It's the beancounter's fault that those protections have been taken as an aexcuse for less and less crew-training over the last couple of years.

Mix that with an ever more simulation-based pilot-training (those good-old 200h First-Officers), and you'll have a nice little situation developing...

 

The "Normal-Law" protections can be killed by switching off two flight-control-computers. Depending on the combination of those (there are 5), you'll either land in "Alternate Law" (basicly the same gains as in Normal, but with less protections) or in "Direct Law", where you're having a linear relation between stick- and control-surface movement (yikes at high speeds!).

In Normal-Law, roll is a roll-rate command, whereas Pitch is a g-command (stick neutral = 1g // fully fwd = -1g // full aft = +2.5g => with flaps dn, that changes to 0g fully fwd, and 2.0g fully aft).

 

There is no need for getting sweaty palms when entering a FBW Airbus. The technology has been installed in fighters for almost 40 years now. There haven't been direct links between the yoke/ wheel and the flight-control surfaces since the 757 (it has all been "artificial feel" since then!) either. You should rather be concerned if the people you just paid for a ticked have done everything possible to get those guys in row 0A and B the best training possible.

 

 

 

and it thinks analogue dials are far better - which may explain why glass (tft) cockpits today have a lot of analogue dial representations

 

That's indeed a very interesting field of science.

The reason why "analogue" round-dials (and to a lesser extent, "tapes") are preferred to "bare numbers" is because they do lots of things:

 

- they give the current value (so does the "digital" numbers-only display)

- they give an "at-a-glance" representation of the situation (instead of just reading "80%", I can see that I'm in the high quarter, but not yet at "MAX"), especially when colour-coded

- they give a good representation of the current value at high rates of change

- they give a rate of change-trend (is my rate of change picking-up, or slowing down?)

Edited February 21, 2012 by Toryu

[Lexx_Luthor 57]

Thanks fellas/fellattes, very interesting discussion.

 

MiGBuster::

PILOT ERRORS INVOLVING HEAD-UP DISPLAYS (HUDs),HELMET-MOUNTED DISPLAYS (HMDs), AND NIGHT VISION GOGGLES (NVGs)(IDA PAPER P-2638) - which is study into pilot errors including spatial disorientation - and it goes into a lot about how the human brain is not so good interpreting digital displays - particularly HUDs and it thinks analogue dials are far better - which may explain why glass (tft) cockpits today have a lot of analogue dial representations - and that bloke in the F-16 vid is telling the pilot to look at the primary dials.

 

That's why I am Lord of the Analogue!

 

I've read that analogue can get out of hand; too many instruments or something. They say F-101 had a crippling cockpit workload but nobody writes exactly why. I've also read that glass is the way to go, with analogue backup, but it has to be done right. Is it ever?

 

Odd perhaps, but when I did flying lessons, from the start I found myself very comfortable relying purely on instruments, and found myself flying at clear night with instructor very quickly. But then I had always read about aviation so that helped, and being a life long sky watcher allowed me to spot other traffic before the instructor, day or night. That impressed him. After a few solos including a short cross country I gave up for fuel costs and went to college, but my plan was to take my FAA flying exam at night. Loved night flying. What troubled me was stall practice and seeing how much practice I would need to confront it, especially at night. Scary creepy stuff there that I'd love to try in challenge but costs and college came first.

 

I never like the HUDs I think mainly because the computer games including that realistic space simulator (forgot) never give you the option of adjusting HUD brightness, so you get blinded at night in the games. Shortsighted game design. In fact that's the reason I quickly gave up on that space sim, and other TheSims games, because the stupid game HUD always got in the way and was far too blinding bright at twilight/night.

[FastCargo 412]

Toryu,

 

Some great info there. Most of your conclusions about 'round dials' are correct...the main 2 that pilots tend to focus on are the quick general 'how goes it' glance and the 'sweep rate' (for rate of change) of the pointer. Both provide quick SA vs numbers only or tapes. Round dials main disadvantage is real estate, especially on flat screens where you have a lot of info you're trying to give the pilot in a minimum of space.

 

Heh, reminds me of my college days. We had to come up with a project to design or redesign something using our Human Factors knowledge. I decided to take on GM and totally redesigned the mid-80s Corvette instrument panel to something far more human factors friendly, yet useful and sexy looking (big main gauges, sweep needles, no silly 85 MPH limit, etc). It ended up looking a lot like the next iteration of the panel....of course, they didn't change until the mid-90s....

 

Though we've had artifical feel in airliners almost since the advent of the jet, and FBW since the 757, I disagree that hard limits are appropriate for an airliner vs a fighter. Fighters are expected to operate at their limits quite often for obvious reasons, therefore, protections are more reasonable to have because you'll be going there a lot. Airliners on the other hand won't be near their limits except in extraordinary situations...to me it seems if I'm hitting that limit on purpose, there had better be a good reason.

 

I would much rather have soft limits that I can overcome if I really, REALLY want to. A prime example is the B-1B. Due to certain aerodynamic features, the B-1B has a quirk where if you fully stall the aircraft, it is now considered unrecoverable. There are details I can tell you as to why, but suffice it to say, you do not EVER stall the aircraft or you will crash.

 

But, the B-1B does not have a hard load/AOA limit. What it does have are protections in place that will give audio and visual warnings, and will start taking out the pilot inputs as the limit approaches. There are 3 seperate, increasingly difficult to overcome channels in fact. The upshot is that the stick requires more and more force to pull back as you reach the limit, to the point of almost requiring both hands to do it. BUT, it can be overcome by the pilot if he really, REALLY thinks he needs every last degree of AOA.

 

In the almost 30 years of operation of the B-1B, there has not been a crash due to a pilot stalling the aircraft, but there is at least one situation I know of where the pilot needed to go past the limit to keep the aircraft from going into the dirt. Admittedly, he got himself in that situation in the first place due to an error, but was able to rescue his crew and the aircraft.

 

In my opinion, this same option is a better idea for an airliner. Give me warnings, do what you can to discourage exceeding the limits, but if I need that extra G or rate change, let me have it. A toggle, guarded switch, something that lets me know I'm demanding more than is recommended, but I've got a damn good reason to do it. I believe in fact at least one fighter has this feature...all the examples of the Hornet.

 

Toryu, you also talked about being able to go into Alternate Law by turning off some computers. Is this something that can be easily selected by the pilot, or does it require circuit breaker pulling / certain failure modes?

 

FC

[Toryu 156]

FC, check out the A320's overhead-panel:

 

http://cdn-www.airliners.net/aviation-photos/photos/0/0/6/1025600.jpg

 

2/3 to the upper top, at the left and right edges of the panel, you'll find the "FLT CTL"-subpanels. (turns out the A320 has 7 FCCs, the structure is slightly different to the A330's)

 

Depending on the combinations of which FCCs are put to sleep, the aircrafts control-laws will degenerate.

 

This document http://www.smartcockpit.com/pdf/plane/airbus/A320/systems/0031/ gives a pretty good description of the Laws, gains and failure modes.

Naturally, the combination of which FCCs to switch off isn't exactly given (except for "two ELACs or FACs gone puts you into Pitch-ALT and Roll-DIRECT").

As pilots usually know which computer usually does the flying and which one is backup, they know which FCC-combination to switch off in order to get into which degeneration of the protections.

That is strongly unrecommended, though (who would have guessed? ).

 

 

On the hard limits:

 

Airbus has done thousands of hours of testing to come up with the protections they have.

Those tests showed that normal line-pilots, acting under stress, may underperform a great deal.

Holding an AoA (i.e. max-performing the wing) isn't all that easy when trying to outclimb a mountain (possibly in a climbing turn, involving turbulence), applying TOGA and retracting the spoilers (I take that scenario as it has tragically been proven real a couple of years ago).

Pitch- and trim-changes during rapid application of power during low-energy flight usually leads to non-optimal climbout-performance under stress.

The studies have shown that a pilot working in a soft-protection environment will overshoot and oscillate around Alpha_max, wasting prescious performance.

The hard Alpha-limit, however, lets the pilot nail the limited alpha-figure and just hold it by applying max aft stick. He also may slam the throttles (sorry: "Thrust Levers" on Airbii) into the TOGA-gate without ever wasting a thought about overreving or overtemping the engines.

The latter feature is a normal FADEC-control authority (thus a hard-limit) and pretty common - even on "manual minded" Boeings.

 

In the end, it's all down to preferrance. Most pilots (even those with reservations!) do transition to that philosophy rather well and come to like it after a few minutes.

I think the approach to the protections by many pilots is wrong:

In the end, they're not designed to put you out of the loop, but to work for you, when you've got a helmet-fire.

 

Whether having the ability for that little ounce of extra G is that desireable in an airliner is questionable in my eyes:

 

Fighters are designed to take an ultimate-load-factor of 1,5 over their limit-load (just as airliners by a matter of fact).

Airliners, however do not have the structural reserves of continuous high-g cycles built into them - they're built fo more total cycles, but wthin the low-g realm.

Therefore, the fighter usually will take more than 150% limit load, while the airliner will snap at just slightly more. Most airliner-pilots have never attended an upset-recovery training or even flown inverted. The feel for Gs (no G-indicator anyway) is thus very rudimentary. I wouldn't trust a pilot to feel the difference between 2.5g and 3.75g (the ultimate-load acc to CS-25 regulations) in a stressful situation.

Also keep in mind that today's airliners are built with less structural reserves and margins (due to a better understanding of fatigue) than those airliners of the 50s (the bulletproof Douglases come to mind!).

 

 

BTW: Keep in mind that the aircraft was designed for 200h ab-initio First-Officers that think that an afterburner is a liquor

Edited February 22, 2012 by Toryu

[+ST0RM 145]

Stupid people fly Boeing products too. Trust me, I fly with them several times a week.

[ezlead 42]

Fascinating discussion gentlemen! FC as usual you are a vast wealth of knowledge.

IMHO too much automation was part of the problem. I can see the need for less crew workload,but is too much emphasis put on the computers.

Even with an all glass instrument panel,do you have the good old needle,ball,airspeed(AOA) and altimeter to give you correct readings?

Back when I was trained in the 70's(US Navy flight school) we were trained in "partial panel". Normal flight and emergencies were learned flying this way.

When all else is haywire,go to the backup gauges.

If you're nose high,full power and still going down,we were trained to drop the nose. Watch the altimeter,it will slow down,then very carefully raise the nose until the altimeter stops.

If you're not alone(in formation or more than one seat aircraft) and you experience vertigo,TELL SOMEONE. They can talk you out of it while you are on the gauges. The 'leans' is a very unnerving thing when in the clag.

My instructor afterward told me"Always raise the nose to avoid a bird strike"

I pushed nose down once and took a buzzard through the front side window of a TA-4j.

The instructor was in the back seat covered with buzzard parts and feathers.

It took him almost an hour to get around to this part of the debrief. Yes,I had no A$$ left when he was done.

Great discussion! It's unfortunate that many of the lessons learned in aviation have to come from accidents.

[FastCargo 412]

Toryu,

 

Thanks for that info on the panel...interesting to note.

 

My understanding on our (admittedly early model) FADECs on some of our CF6s and PW4000s is that it doesn't prevent an overtemp at Firewall Power. And in fact, we have to watch out it doesn't try to transient overtemp itself on a hot, high day at calculated TOGA power. On the PW4000, it'll trim the N1 to match the calculated EPR, vs on the CF6 it'll just trim the N1 to match calculated N1. I could be wrong though.

 

I understand the rationale behind the hard limits...I don't agree with them. You can have a hard limit aircraft available with a toggle to remove those limits. A pilot can have the understanding that by removing said limits, he could possibly break something major. My opinion is that if I'm removing that final safety...it's because I have calculated the consequences of having them are worse than the consequences of not having them.

 

There has not been an engineer yet who has found every possible fault an aircraft (especially its software) can have. When the unexpected, unanticipated happens...I want the human in the loop to have the ultimate, final say so.

 

Most airliner-pilots have never attended an upset-recovery training or even flown inverted. The feel for Gs (no G-indicator anyway) is thus very rudimentary. I wouldn't trust a pilot to feel the difference between 2.5g and 3.75g (the ultimate-load acc to CS-25 regulations) in a stressful situation.

Also keep in mind that today's airliners are built with less structural reserves and margins (due to a better understanding of fatigue) than those airliners of the 50s (the bulletproof Douglases come to mind!).

 

That right there is a foul (in bold - my emphasis). In my opinion, ALL airline pilots should have upset-recovery, spatial disorientation, and altitude chamber training. Yes, you may only EVER see something like that happen in the aircraft once...but its wrong if that is the first time you have ever seen it in a heavy aircraft.

 

As far as G's go...3.75g is 1.25g more that I can use if I really, Really, REALLY need it. And G-meters are easy to install... . Heck, you could even have it pop up during an aggressive pitch up (the computer recognizing that you are seriously trying to pull).

 

FC

[busdriver 35]

Bullethead's (how shall I phrase this...) misunderstanding of Airbus FBW system and logic is often found amongst airline pilots, but only pilots that have not flown a Bus. Kudos to FC for trying to illuminate and educate.

 

It has been my experience that most american pilots prefer Boeing products. I really liked the 757. But I prefer Fifi (319/320). It seems to me pilots that love it the most are former F-16 guys/gals like me. We "get" the FBW logic of Normal >> Alternate >> Direct Law. My employer recently included stall recovery training during recurrent simulator training (as a direct result of the Air France crash). It requires us to "fail" two computers to get into Alternate Law, and we no longer automatically go to TOGA (exacerbates the nose pitch up and possible secondary stall). I am firmly convinced that years of flying upside down and pulling Gs makes this training less stressful for me than say a pilot with ZERO military fixed wing experience. Direct Law is scary for some folks, but when you explain that it's sorta like flying a DC-9 you see the light bulb come on over their cranium. My employer considers a DIRECT Law approach and landing to be an emergency, most carriers do NOT. I do not consider it an emergency.

 

WRT Boeing -vs- Airbus...recently had a mechanical delay leaving CVG for SEA due to a scheduled overnight engine change. While we waited, two Boeing employees cornered me and my FO (co-pilot) to get the "real" gouge on the delay. One guy said he didn't like Airbus, that his 737 was much better. He was in fact part of the 737-900 team that is selling them to my employer. He was rightfully proud. When I asked if Boeing was putting the same ole, cramped and NOISY cockpit on the front of their shiny new 900, he sheepishly (think averting his gaze and sorta mumbling) admitted it was pretty much correct. "Ahhh, we're ahhh making a couple changes, but yes it's the same." Give me my QUIET, roomy cockpit with its side sticks, tray tables, and being able to see my wingtip (great for taxiing on congested ramps).

Edited March 1, 2012 by busdriver

[+Jug 99]

I could regale you with a few stories of Boeing software not behaving correctly either...at least one of which has caused a crash. So don't generalize a specific brand based on one crash incident.

 

Now, what you can generalize is a training fault. Up until a little while ago, stall recovery was based on the idea of 'powering' out of the stall. The idea is that modern airliners have tons of power, and that typical stall situations were close to the ground. Therefore, the idea was to lose as little altitude as possible in a stall recovery. Most airlines were training to this standard...using the aircraft's power to gain airspeed back.

 

This accident shows the fallacy of that recovery technique. The stall was so deep, that the engines would never power the aircraft out of the stall...it would simply fall like a leaf (a very heavy leaf) into the water. Part of the reason was the training in only lowering the nose enough to accelerate, not enough to fully break the stall. This accident (along with others) has finally started shifting the mentality back to what we all learned in basic flying...break the stall by lowering the AOA, get some flying airspeed back, then pull back up...especially if you have buttloads of altitude below you.

 

FC

In my experience, and with enough altitude, you can take your hands off the controls and the jet will fly its way out (sorta). Due to the hazards of spinning an aircraft, many training programs do not really train pilots on how to handle this situation. I do recall a briefing following the loss of a B-52D returning from Vietnam to Guam where the simple pilot stuff was re-iterated. The thing I remember most is that pilots get involved in talking to each other and over the radio and forget that there is a sound effect to getting slow in an aircraft. Wind noise or in this case, the lack thereof. The poor Buff crew was exhausted by a long mission and the pilots just didn't listen for a moment prior to taking the action that ended up losing the aircraft and one or two of the crew. They thought the auto-pilot had taken them to the Mach limit, when the jet was so slow it was wallowing. Nobody listened before yanking all 8 throttles to idle and pulling back on the yoke to maintain altitude. Wallowed like a really big leaf all the way down to the altitude that the aircraft was abandoned. Striking similarities between the Buff loss and the Air France loss. Bet the Air France pilots would have known what was up if someone had told them to listen to the wind noise. (yes you can still hear it in large modern aircraft). Sad for the lost souls. RIP

Edited March 5, 2012 by Jug

[Vampyre 24]

Or this incident to a Eurofighter Pilot:

 

http://www.indiandefence.com/forums/f17/eurofighter-typhoon-4731/index19.html#post139832

 

Ahh, I remember that one. I was the Auxiliary Security Force Platoon Commander at NAWS China Lake from 2006 to 2009. I had my guys watching the bird overnight along with a couple of 17® Squadron personnel. When it landed, there was a large black plume of smoke and it left its targeting pod and big blue LGB's scattered down Runway 26. The Typhoon started to burn as it slid down the runway and I was sure it was going to be a total write off due to the damage I saw. Heck, there was a lot of composite material was just falling off the machine where it had burned. My I told my guys to stay away from from the aircraft and maintain their watch from upwind of the aircraft due to the investigation and the fact that the composite material was very harmful to their health. It stopped about 400-500ft short of the 4k ft marker. Anyone know it that jet ever flew again?