One has to wonder why anyone would design a plane with a T-tail. I presume there are some benefits to that design that still make it attractive but that possible characteristic seems a big ding against that design.
Computers can handle routine flying no problem. In a sense, what the pilot is there for (beyond monitoring the computer) is to come up with solutions to unforeseen problems that computers aren’t programmed to handle. In other words, to think creatively when the crap hits the fan.
Simulators have distinct limitations. I am not aware of any flight simulators that can faithfully replicate a 40 degree roll, for example. For some aspects of flight simulators are indeed excellent but they don’t cover all situations, and the situations they don’t cover tend to be those on the extremes.
Not every problem or emergency situation is fixable. I have seen flight manuals that have explicitly said “If you do X you will die” in exactly those words. Solution? Don’t do X.
First of all, as the document linked to states, there is no “AoA indicator” for the *pilots *in that aircraft. There is one, but it’s for the use of the computerized flight system. The pilot’s information on AoA is indirect and derived from things such as airspeed - which was malfunctioning in this case. So there was no working indication to glance at in this instance.
Malfunctioning ailerons, flaps, or really any control surface on the wing that is too abruptly changed could induce a roll. That’s just for starters.
I believe you but that seems amazing to me. I thought an AoA indicator was one of the most fundamental instruments pilots need/want in a cockpit (fuel gauge, air speed, AoA). I suppose people a lot smarter than me had their reasons for leaving that out and certainly was a conscious design choice. I just cannot imagine why.
Would those faults make the plane roll back and forth or just roll in one direction? Unless I misunderstand it sounded like the plane was violently rocking left-and-right.
It depends. Sorry I can’t be more definitive than that, but maybe **LSLGuy **can?
Whack-a-Mole: I dislike the multiple quote tit-for-tat response style, so I’ll try to address your quite reasonable questions without resorting to picking apart your posts.
Once in a deep stall there is no assured way out. The manufacturers say so. There is no procedure for all crews to practice in a simulator.
Further, the training simulators used by the airlines are not full fidelity all the way to the edges of the flight envelope. So the fact some technique works or doesn’t in the training sim is no assurance it will or won’t work for real. The manufacturers do have engineering simulations all the way to the edge, and if they say they don’t have a reliable way out I tend to believe them. But I’m sure as hell not going to just sit there with my arms folded until the ground arrives. I’m damn well gonna do something.
The bigger point is there are always unrecoverable situations when flying airplanes. Getting pointed straight down is probably unrecoverable even though the recovery procedure is trivial to explain or to do. So the message for pilots is don’t go there. The only way to win is not to play.
For whatever reason, airliners historically have not had AOA guages. Supposedly the 787 will have it. I think the late model 737s have it available as a customer option displayed on the PFD (electronic horizon display) or the HUD.
For all other aircraft, AOA might be available as an input into the autopilot or stability augmentation system, but it isn’t displayed to the pilots. Why? My guess is that oOther than *in extremis *it isn’t all that useful. And back in the 707 / DC8 days the instrument panel was already waay too crowded with round dials. And it costs money.
I don’t doubt the pilots knew they were in a deep stall by the time they started descending rapidly. The problem is that the situation was already almost certainly unrecoverable.
I think you misunderstood my comment about magic flight controls vs 40 degree roll excursions. Which is more an indictment of my writing than your reading. What I meant was this …
The news media was reporting that this descent was not scary. Not having read the interim report before my first post (and saying so) I suggested that was probably poppycock unless maybe the automation was much better at damping post-stall wing rock that I knew of. Then I went on to read the report which said they *did *have 40 degree wing rock. So in my next post I said they did experience wing rock which is typical deep stall behavior. Sorry to be confusing.
T-tails are needed for designs with rear-mounted engines. e…g 727, DC9, EMB 135, etc. As I said above, both Boeing and Airbus products without T-tails have crashed due to deep stall. It seems the marginal increase in deep stall danger with T-tails is either less than was previously thought, or is/was mitigated by other design features. I personally don’t see T-tails as an obviously defective or inherently too-dangerous design. Presumably the guys who designed them & continue to design them don’t think so either.
**Broomstick **introduced the idea of control malfunction as an alternate source of uncontrolled roll. While true in the abstract, I think it’s a red herring here. You two may be miscommunicating on whether you’re talking about aircraft in general or this specific incident.
My bottom line: The thing which is legitimately surprising to you is the idea that they could go from fine to screwed that quickly and without clear & unequivocal warning or a clear and unequivocal plan to counteract the deteriorating situation before it was too late.
It’s too early for anyone to say for sure what really happened there in enough detail to answer your underlying question. But we can say that
a) in a jet, things can get unrecoverably out of hand quickly.
b) a wrong move early can make the problem a lot harder than it was a moment ago.
c) Airbus’s design philosophy has a history of being more helpful or better in good conditions than the traditional methods, but has more than once had a surprising downside when an undesigned-for situation occurs.
d) sometimes “obvious” technical remedies or preventatives aren’t installed because there are literally hundreds of other plausible accident scenarios, each with its appropriate technical remedy. Airplanes are normally pretty darn carefully designed, built, maintained, and operated. But stuff still slips through the cracks occasionally in each of the 4 areas.
Quoth Richard Pearse:
More precisely, you could also have a roll or other maneuver where the magnitude was one g throughout, but in that case, the direction (relative to the plane) would be tilting.
On the question of how peaceful the flight was for the passengers: When you’re flying through a storm, you expect some turbulence. Would the shaking etc. have necessarily been strong enough to be distinguishable (to the passengers) from annoying but routine turbulence?
I guess this is what I find surprising.
My friend, who flies weekly all over the country, is mildly uncomfortable in a plane. No biggie but he has his moments where a little paranoia asserts itself and he told me he usually calms himself (again I do not want to overstate his fright) is to tell himself planes do not simply fall out of the sky. With this accident he is a bit spooked because apparently that is what happened.
I am not suggesting flying is easy or without risk. Clearly it is risky but in general, as you mentioned, the planes are well built with many safety features and we have (generally speaking) well trained air crews. So, despite millions of flights a year relatively few planes crash. So, while I 100% believe you that there are unrecoverable situations it just seems so unlikely as to be near impossible barring the pilot intentionally getting the plane in that position (I am not saying these pilots did anything wrong intentionally…I have no doubt they did their best to save the plane). The plane may be losing altitude quickly but as noted it is 3.5 minutes to the ground. Barring total loss of controls (mechanical failure) it is weird to think the plane is in a position from which nothing can be done not to mention how the plane manged to get in that position in the first place.
Of course with anything that has risk if you roll the dice enough sooner or later you will come up all sixes. Disasters are almost always a series of improbable events that line up to get the bad result. Break any one of them and the disaster would be averted (which is only ever obvious in hindsight).
The above does not count for things like TWA-800. Blow off the front 1/3 of the plane and then yeah, it’s all over no matter what.
If you mean the Air France flight LSLGuy noted the plane was rolling 40 degrees back and forth. The passengers would notice.
This article in the UK Guardian quotes a professor at Brunel University (a member of the Royal Aeronautical Society) and an active pilot of A330s, both of whom say that the pilots would have had a pretty awful few minutes as they struggled frantically to rescue the flight, well aware they were about to die, but the passengers apparently wouldn’t have felt much more than “mild buffeting”.
Well, no, that’s not the case here - a whole series of events had to happen prior to the airplane’s final plunge. Whether or not the accidents was preventable, there were reasons it occurred.
You know, I just can’t believe that. Pardon me, passengers only feeling a “mild buffeting”? That is, pardon the expression, horseshit. The storm alone certainly could have induced more than “mild buffeting”.
Meanwhile, I’m pretty darn sure that if an airplane I was in was rolling 40 degrees left and right I would notice that! Anyone not buckled in would be knocked off their feet, anything loose would be either rolling around or flying about the cabin space. I’ve been in airplanes banked 40 degreess (and even more). If it’s a coordinated maneuver you’ll noticed an increase in g-force. If it’s uncoordinated you’ll notice that, too, with the previously mentioned loose stuff roaming around the cabin and your own feeling you’re sitting on a wall instead of the floor.
It’s wishful thinking speaking any time someone tries to gloss over that the last 2-3 minutes of that flight was anything other than terrifying for those aboard.
Maybe I am mis-naming the device I am thinking of.
I mean the instrument that (historically) is a ball floating in a liquid with markings on it that tell the pilot where the horizon is and the plane’s orientation to that.
You can see it both on the glass display in front of the pilot as well as the “old” mechanical version nearly dead-center in this picture of a 737 cockpit.
I always thought that was common equipment on an airplane and I would think looking at it the pilots could tell they were pointed up.
Well sure. He (nor I) meant the plane is flying merrily along and then without any problem whatsoever it just plummets to earth.
Of course there has to be problems and serious ones at that because generally planes do not just drop out of the sky. When it is a mechanical failure that is more understandable (e.g. wings iced up and wrecked the lift the plane gets and it crashes or the hydraulic system is destroyed as happened on the DC-10 flight 20 years ago in Iowa).
In this case though, while there were mechanical failures mainly (it seems) stemming from the pitot tubes the plane itself, near as I can tell, was still flyable. Yeah it is not good losing that information but nothing that made the plane literally unflyable. Instead, despite an ability to continue flying (engines working, control surfaces working and so on), this plane dropped out of the sky…literally.
That’s the Attitude Indicator a.k.a. “Artificial Horizon”.
I imagine you can be nose down and still have positive AoA depending on how fast you’re dropping:
Seems like under normal circumstances knowing pitch relative to ground is “close enough”… but emergencies happen under not normal circumstances.
Thanks.
I actually called it by the correct name in Post #12 then for some reason switched my terminology for it.
My fault for confusing the two.
As an aside, reading a summary of the accident, they noted what the pilots were saying and it was in English.
I know all commercial pilots must speak English to ATC but can they chatter in their native tongue in the cockpit or is that also a place where only English must be spoken (at least when doing official airplane stuff…I’m sure they can order dinner from the stewardess in their native language or chit-chat about their favorite football team)?
I thought it had been translated from English, not that it was in English, but hey, I could be wrong.
Of course pilots can communicate with each other, their crews, and so on in languages other than English. English is the default common language used where there are not other common languages between people. And perhaps in some places it’s required regardless. However, in-cockpit between pilots they can use whatever language they wish so far as I know.
I know when talking to ATC the pilots and ATC all speak English. This is even true of (say) a Chinese flight landing in China.
I was not sure if official business in the cockpit likewise had to be in English mainly to keep crews used to speaking it rather than in a panic defaulting to (say) French when the ATC person doesn’t speak it.
ETA: Akin to the “quiet cockpit” where crew is not allowed to chit chat till they have taken off. This is true even if they are delayed on the ground. This is to keep their heads in the game and not lose focus as some accidents have occurred prior to that rule (they forget where in the checklist they are or something and something critical gets missed).
The French talk in French to French ATC, so I’d be surprised if they were speaking English in the cockpit.
Huh…I guess I misremembered.
I looked it up and apparently, while the default language of ATC communications is in English, they can and sometimes do speak their native tongue to pilots who also speak it.
I thought it was a rule to avoid mistakes (busy ATC maybe talking to lots of planes and remembering which one is a native language speaker might be difficult). Guess not though.
Ignorance fought. Thanks.