You can't hope or will the airplane to fly. If it's not flying it needs less AOA. Period.

You can't say "I don't like the nose that low'. If the wing needs AOA reducing AOA is the driving force, not some desire for a 'normal' pitch attitude.

Did loss of airspeed in the sim. During recovery we had 10 degrees nose low at max power(actually restricted to 75% N1 due to EEC failure resulting from loss on data input!). CKA said "don't put the nose that low." Silly boy, AOA gauge demanded it. Pitch attitude was being driven by the AOA gauge.

If you've done acro or fighter flying you've probably seen amazingly slow airspeeds. Less than 1G, and low AOA, is what allows that. I've seen the airspeed indicator pegged against the stop (<60 kts), when the actual stall speed was 120+ kts, without being stalled. But not for long. ;)

Airbus Drivers,
Next time you go for a sim check, just ask your check air man to freeze all of your pitots during a climb (lets say passing 30.000'). Everything functioning normally, with AP ON...
Since pitots were frozen at the same time (no significant speed differences between ADR's), your ECAM will stay silent until high speed protection actuates and takes your aircraft into a deep stall...
You will have to force your aircraft status to change to Alternate Law, in order to be able to push your nose down...
That experience will tell you a lot about the aircraft you're flying...

The headwind/tailwind scenario as a result of the erroneous TAS computations with changing altitude with blocked pitots is absolutely realistic. (I work for the company that built your 747-400 simulators) The actual winds set the simulation were probably either calm or stable.

I urge any airline pilot who has never seen this effect firsthand to give it a try the next time you're in the sim. As flyburg has said, it is a real eye-opener with regards to AF447.

AFLOOR, Is there any reason to include ICED probes? Not to? What do you think of the possibility 447 may have lost her reads via airmass volatility alone?

Uh?
Doesn't high AoA protection have a greater priority than overspeed protection :confused:

BTW, I also was under the impression that getting 3 pitots freezing at exactly the same time is... let's say extremely unlikely. Wrong?

AZR

Hi. I recall from the "Another 447 avoided" that overspeed warning is primary over STALL warn...

Lyman

Fwiw: if the probes are blocked for the sim ride, simultaneously then it is not a true 447 profile....as above, freezing all three at exactly the same time is virtually impossible. I believe that is why BEA will not say ICE blockage caused UAS. If airmass/turbulence, or ICE, it happened concurrently, and frankly, IMHO, for all three to ice at all via micro granulae is far fetched. Any transition from 100 knots on the nose to 100 knots on the tail would cause extreme disruption at the nose, and the pitot probes, ( to a lesser extent, the statics).

We know unqualified pilots flying together is unsafe so if the regulators don't fix it maybe the press will have to. We will just have to be patient for another couple of AF type crashes. Sad, isn't it?

Bubbers
I'm not trying to cause great mischief with this question, but how will we tell the qualified from the unqualified pilots? Both types will be wearing the uniform, sitting in the seats with the forward view, and carrying the ATP certificate in their wallet. Just what criterion will we be using?:E

I'll bet there guys&gals out there who fully believe they are qualified but would not fit either my or your definition of qualified.

So how do we get them properly qualified?

My airline, 30 years ago, had me take a check ride in a 4 engine turboprop I had never flown and do ILS's to a single engine approach to get hired. That is how you can find the pilots you want. We hand flew all approaches so the computer monitors would not be accepted for my job. That is how you hire a real pilot.

Yes, the airlines are hiring the monitor pilots because they are cheap. Maybe we can raise the standards to what we had 30 years ago. Maybe we need to see if the pilots now flying can handfly before we let them fly together. Automation is great but it should just help you fly, not be your only way to fly.

AOA
 

I doubt the Attitude indicator and FPV can show you the AOA.
The FPV has a trend vector with power inputs, therefore your nose may be level but FPV down like on an approach. That doesn't give you the AOA, am I right?

In this case they don't have to freeze at the same time, but they have to freeze in the same manner. If a pitot is blocked at the intake and at the drains simultaneously, you wouldn't notice anything until you change altitude.

1) I'm not convinced that this is simply a question of more/better flying experience. I agree about insufficiently qualified second officers, but the belief that there is something fundamentally missing in airline/type-rating flying training to me ranks with me alongside the idea that fly-by-wire is somehow "less safe". For the one-in-a-million event which led to this, there are the one-in-a-hundred events where overbearing, arrogant captains ended up effectively flying airliners "solo" because they had no confidence in their first officers (ie. were unable to operate an airliner as a crew, as the aircraft had been designed to).

2) Even if it is, I don't know how people expect to change this. There is much less military flying now - should tax rates be put up by 2% to pay for increased defence expenditure? Should pilot qualifications be increased in cost by £10000 to provide a greater diversity of experience? Who is prepared to pay for this? And how could anyone measure whether the extra training provided suitable economic benefit? And what extra experience should be provided? How would you know that you had provided all the training that would be needed to convert an "unsurvivable" event into not only "survivable" but "recoverable"?

3) The idea that thirty years ago we were in some kind of golden era where pilots were real pilots, men were real men and blahblahblah, is simply not borne out by the facts. The absolute rate of accidents has fallen and is falling - see the graphs on this page - whilst the number of commercial flights has increased. The argument that "we need pilots with somehow 'better' experience" is not statistically supportable.

To my mind, the approach of identifying a threat, then providing training to deal with it - steered by regulators and airlines - is entirely appropriate. The process that is happening now will ensure that professional pilots worldwide will have a greater appreciation of this combination of threats - it provides the extra experience that people say is missing.

Perhaps you misread. Overspeed warning took priority over A/P disconnect warning. There was no stall warning because the airplane remained in normal law.
It wouldn't cause disruption of pitot or static, but it would immediately deprive the airplane of almost all lift and drag. IOW in AF447 you wouldn't be able to pull 1.6 g at stall warning.

ray.boeing: No. The FPV will give you AOA indirectly. It is the difference between the aircraft attitude and the FPV angle. However I am under the impression that the FPV is not entirely inertially driven so may have errors added when the pitots/statics are obstructed.

Which brings to mind is question:

Can static ports become frozen in flight? I know pitot tubes can, but static probes?

And are the chances that pitot tubes will freeze much eqrlier than static ports? i would say 99%. I deem that icing related unreliable speed situations in cruise flight will always be pitot related. So you will be able to rely on Altitude indications and FPV. Angle of attack can be derived from the difference between body angle and FPV.

Aguadalte

That scenario of the false oversped triggering undue high speed protection, when you are actually flying very slow, is dreadfull. But I believe you can still use manual pitch trim to achieve pitch down.

By way, what will happen in a Boeing in the same circumstances?

As I always say, the most difficult partof an unrliable speed scenario is becoming aware that speed is unreliable, in the first place. If you don't come to that conclusion timely, you are fu*ked.

Then, My opinion is that the procedure needs more refining. It is too "take off oriented". You can be at high level with "safe conduct of the fligh" absolutely "impacted". Then what do you do?

Hi Lyman. :)
I'm sorry, you recall wrong here.
High AoA (Stall) protection has priority over other protections (IIRC, I stand to be corrected and hope I will not on that topic).
Stall warning has priority over other warnings.
Why? Because stall was deemed more dangerous.

Hi HN39. :)
AFAIK, they have to freeze at the same time and in the same manner if to fool failure detection mechanisms (comparing in real time values from 3 probes).
My point was: such an event in real conditions is extremely unlikely, that's why detection are based on that assumption. Don't you agree?

AZR,

If the drain of a single pitot is blocked, and the intake of same pitot almost at same instant, then the total pressure inside the pitot is 'frozen', no change to detect. Same for a second and third pitot some time later. The IAS changes when the static pressure changes, i.e. the altitude. IAS increases with increasing altitude, and vice versa. The IAS from all frozen pitots change in the same manner, no differences to detect.

What IMO makes this scenario somewhat unlikely is the absence of turbulence in the simulation. Turbulence was present in all UAS incidents studied by BEA, and would cause altitude variations causing airspeed anomalies that would trigger detection unless several pitots froze simultaneously.

Microburst2002: Yes, static ports can get iced over in flight. In the `70s there was an incident invovling a Trident operated by BEA/BA which experienced freezing rain runback on the fuselage which blocked the static ports. It was in the BNN hold at the time. When the stick push operated it promptly dived through several levels of the hold missing other aircraft. My neighbour at the time was the F/O.

Regarding manual use of the THS to control pitch - yes it is always available and in some situations may be needed to overcome the ineffectiveness of the small elevators. This in my opinion is one of the great untaught "gotchas" of the FBW Airbus`s. The THS is NEVER NORMALLY moved by the crew in flight but as AF447 found out it may have helped. The same goes for the A320 loss at Perpignon.

The total pressure will freeze, but remember that the static ports were available and working 100% all the time in the AF447 scenario. IAS is still equal to Pdynamic, which is derived by substracting Pstatic from Ptotal.

The pressure variations in the turbulent air will still find their way to the IAS via the static ports, and this is of course also the reason why climbing will give you the impression aircraft is accelerating. What was also significant in the AF447 case is that the turbulence will cover up any other cues that the aircraft has stalled (stall buffet), and the FBW will mask any change in roll response of the flight controls due to the extreme AOA, as I recall that the roll rate response vs. stick deflection is linear in alternate law. FBW being FBW, it will always try to give you what you are asking of it. So the aircraft will appear to respond normally around the longitudinal axis, and the only thing telling you otherwise will be the compass heading turning in the opposite direction. But trying to figure that one out when you are descending at 10000fpm through a CB at night with a nose-up attitude with your aircraft telling you to pull up even more is an exercise of futility.

With regards to Airbus vs. Boeing: the Airbus overspeed mode was commanding an increase in pitch through the flight directors, which was followed religiously at least until the aircraft reached its apogee at 38000ft. This continuous backpressure on the stick caused the THS to trim all the way up, leading to the deep stall. I doubt they even realised that the THS was at the position it was in at any point as you are not supposed to fiddle with it yourself but let the automatics handle this, even though the captain correctly remarked on his return to the FD that the aircraft was stalled. It has been argued that if they just let go of the controls it would have allowed the aircraft to recover itself, and this is probably correct. This tells you how a Boeing would have fared in the same situation: the lack of autotrim on Boeings leaves the THS in the same position unless you conciously tell it to do something else using the trim switches, and this leaves open your avenue of sensing that the aircraft is stalled as you are unable to maintain a nose-up attitude as the aircraft loses airspeed. It's become pretty clear that in the same situation, a Boeing would not have deep-stalled. Not unless the crew trimmed up by themselves while not looking at the stab trim indicators.

Micro:
As I said, you will have to "change the Law" in order to pitch down, otherwise, in Normal Law, the Overspeed Protection will take control.

To those who say that, this is a very unlikely situation, I would like to ask if you think this would be absolutely impossible to happen?

Altitude variations affect IAS via the static ports. "Turbulent air" as such does not.
Mach buffet is a violent high frequency shake of the aircraft that is very different from turbulence-induced g-variations. The airplane had left the turbulence before it stalled.
Once stalled, the airplane is effectively uncontrollable in roll, its reponse to a roll input is often opposite to that commanded, at any rate quite different from normal.

No. In Alternate 2 law, roll is direct. Meaning sidestick deflection gives proportionnal control surfaces deflection. This is different than the normal mode, and FBW doesn't try anything here, no "masking".

What flight are you talking about :confused:
If still AF447 : sorry, this one never get to overspeed.

Same question. If that's AF447, I fail to see anything suggesting any of the crew members ever understood the stall situation.

Two remarks:
- It still remain to be proved that elevators only aren't enough to maintain stall (at a lower AoA than that obtained with the help of the THS, maybe). IIRC knowledgeable peope (of which I'm not) suggested otherwise.
- What do you mean by "the lack of autotrim on Boeings"?

[edit] May I suggest we move to the AF447 thread if I undestood correctly that was the topic at hand? We're hijacking flyburg's thread, here.

This may not be apparent as the output of the altitude calculation from the statis prerssure to the altimeter is filtered, but I assure you that it does.I am talking about the stall buffet. The aircraft was at that point flying too slowly to induce a mach buffetThere is most definitely a degree of residual positive roll control in an aircraft of conventional design when deep stalled. How much exactly for a particular aircraft in a particular circumstance is a question nobody can answer for sure as this has to my knowledge never been tried in a large aircraft (and lived through), but the windtunnel data, flight test data and computer models which are used in the aerodynamic models in simulators leave little room for doubt. I will concede however, that this is way beyond what any sim is certified for for flight training.

Fair enough, it seems I had my modes mixed up.Have you read the CVR transcipt?My point was that with elevators alone the aircraft will drop the nose again when the elevator backpressure is released, but this may no longer be the case when the THS is trimmed fully aft.I know of no Boeing type which has an Airbus type autotrim system that automatically trims the THS to relieve pitch input. In manual flight, even the 777 and 787 have to be trimmed manually for airspeed using the trim switches. This does not take into account some functions where the trim is adjusted automatically with flap and speedbrake deployment, but the fact remains that the pilot is almost completely out of the loop with regards to the THS in the Airbus.

I am talking about the Mach buffet that AF447 was entering at 02:10:55 at M.67 that is shown on page 43 of Interim Report #3 and described in the associated text.

[edited] A-FLOOR, I moved my answer to the AF447 thread, here, in order to comply with my own remark re: "hijacking" of the present thread ;)

Hmm, I'm afraid I'm not sure to which case you are referring?
In case of the A340 Zoom Climb it was overspeed protection that send the aircraft into a climb but it did not stall. AoA protection law kicked in and kept it at Alpha_Prot. No stall here, and no alternate law either.

If you are referring to AF447, there was no overspeed event, it was in alternate law 2 due to the ADIRU's signalling Unareliable airspeed (Icing of pitots) and it was sustained NU commands by the manually flying PF that caused the THS to finally support his efforts and go to a significant NU Trim setting. This combined with further mainly NU commands on the sidestick kept it in the stall.

Alpha_Max is a HARD protection which cannot be overriden as long as it's active (not the case in AF447 due to Alt2). High speed protection might win against Alpha_Prot but not against Alpha_Max
It is not THAT easy to fool the Airbus protections. That takes much more finesse and or bad luck (stuck AoA vanes in Perpignan).

@flyburg: Apologies for also taking part in the AF447 thread hijacking ;-)

Two A340 'level bust' incidents have been discussed recently on this forum: TC-JDN on 2/10/2000 and F-GLZU on 22/07/2011. In both cases there was an overspeed warning but the overspeed protection was not activated.

I was referring to the second one where at least the FDR trace shows 2 overspeed events right at the beginning of the incident.
See http://www.bea.aero/docspa/2011/f-zu...f-zu110722.pdf
page 18.
But indeed it seems the pitch up was due to Sidestick input although the AoA starts to increase prior to deflection of the S/S which I attributed to overspeed protection. Looking closer at the traces the pitch only starts to increase after the NU S/S commands.
In the text overspeed protection is also not explicitely mentioned, therefore I come to agree to your statement and stand corrected.

Ahem, sorry but...
"Au cours de l’événement, la protection haute vitesse ne s’est pas activée."
=> "Throughout the event, the high speed protection did not activate."
Footnote 4, page 3.

Yes, static ports can get iced over in flight.

That may be true.

However, the static is very sensitive to airflow variations. Put a minor obstruction on the skin somewhat upstream and the PEC can alter substantially from what the AFM suggests.

Keep in mind that a lot of effort in the certification test program goes into establishing the PEC information for the AFM.

Use of THS
 

Good thoughts re use of THS as recourse of last resort. One perhaps could file this away under "what to do when all of the usual drills and memory items aren't working" file. I suspect however that the crew of AF447 never really knew that they were in a stall, nor what their real AoA was in the last minutes of flight......:sad:

B777 has no autoreim in that sense, but it is not a conventional THS either. It moves without pilot inputs, same as elevators, depending on actual speed and trim reference speed, which is what you select with the switches.

So, if speed is wrong, if speed is overspeed (for the computers, I mean) what would happen in a B777. Its protections are different tha those of airbus. No uncommanded pitch up or down, but there are forces induced in the control column to cue the pilot. In this case it would mis,ead the pilot, right? It would be too stiff for pushing, I deem...

Computers are computers. They have a big problem. What happens when they are doing the wrong thing without detecting it is tthe wrong thing.

Just a small point of order here. Boeing offers the AOA in all of it's current airplanes. Delta and American are the only airlines that I know for sure have the AOA in the 737NG and 777 series aircraft.:ok:

"Computers are computers" - garbage in/garbage out.

However, the fact remains that accident rates continue to fall, not only per million flights, but in absolute terms. Yes, we need to continue to develop the software models, but the argument that flying is more dangerous because of increased computerisation is simply false. I am not convinced it's even possible to argue that aircraft with computerised protections are more dangerous than those without.

Absolutely.

I'm talking about the different nature of computers as opposed to mechanical systems.

When computers are involved, wrong data that can't be dismissed by the computers as wrong, can make the computer make very nasty things. The more complex the system is, the more involved one computer in the system and the more systems interface that computer, the worse effects such a malfunction will have.

Wether it is a Boeing or an Airbus, computers are computers.

Computers are protected against that in various manners, like "watchdogs", "voting", control and monitoring dual channels and "dissimilar redundancy". When a computer is not working properly, it is very important that the computer is declared invalid, either by itself or by other computers, so that its outputs are neglected.

The simultaneous and identical freezing of all three pitot tubes will make all three computers be in error, which makes impossible to detect by voting. So it is necessary some added function to avoid that situation, such as probe ice detectors or a "reasonableness check of IAS" using data other than pitot, I think there is already something like that invented.

I'm still curious about what would happen in a B777

Oooopsie, now that you point me to it....

Guess I need to give my glasses a good cleaning :}


On a more serious note:
Is there any documented case of an overspeed protection induced Pitch Up in an A330/340? Apart from this one where I wrongly assumed it was the overspped protection that initiated the climb I'm not aware of any other suspected case on these types. Did I oversee something?
Has it really never been used in anger?

MEIKLEOUR #59
AVEROW #72

If " The THS is NEVER NORMALLY moved by the Crew in flight... " it might tend to be forgotten.

If a car with hydraulic brakes has a hydraulic leak, the hand brake is a separate system which can be used... And it should be used, just occasionally, to remind the driver that it is still there.

( A family car had a hydraulic leak recently. Luckily the young driver DID remember. All was well...)