News French plane lost over Atlantic

[Urwumpe]

What then a pilot should do if a pitot tube fails to prevent plane from falling out of the sky?

Use the other two to three.

If they all fail, do your damned best to keep the plane flying - direction or speed or altitude is not as important then as stability. GPS will tell you good enough where you are to keep you flying.

If your best is not enough... :hail:

 

[garyw]

I may be wrong but maybe the RAT could help with airspeed but I think that is unlikely

I don't think it does, it's there for emergency electrical generation via wind power.

Even if the RAT did help with airspeed what would the FMC take airspeed from? The RAT or the PITOT tubes? The problem here is that the FMC doesn't know which one is correct so can't make a judgement call.

This leads onto another problem. Let's say that you have three pitot tubes and something else for measuring airspeed. lets say that all three get blocked with ice. The FMC will see three pitot tubes presenting more or less the same, incorrect, information so it can't "vote down" one of them...

 

[Urwumpe]

Yes, and the FMS of the Airbus A330 did in fact detect the problem with the air data probes and switched to alternate law, which works with just one probe giving you dubious data, but also has all protection and stabilization of the fly-by-wire reduced.

The frozen probes alone can't explain the accident, that is one aspect that the pilot defenders ignore most of the time. There must have been a crew action that was not helpful for keeping the plane in the air, and the rapid descent of an intact plane is a pretty strong sign of a bad situation.

It could have been even spinning, without the FDR found, we can't tell what the aircraft did in the final minutes.

And what if the whole discussion about the pitot probes is leading the guilt to the wrong object? What if the accident could have been caused also by some event that came later? We can't tell yet.

 

[Linguofreak]

What then a pilot should do if a pitot tube fails to prevent plane from falling out of the sky?

Under normal conditions, if he loses all his pitot tubes, he might just have to be extra careful. In a thunderstorm at night, he may well be screwed.

 

[ex-orbinaut]

I believe it is part of the pilot syllabus but it's not something that airline pilots would practise in a simulator.

It is...

What then a pilot should do if a pitot tube fails to prevent plane from falling out of the sky?

Your previous post to this was on the right track. Power and attitude equals airspeed. Know the numbers. There is a procedure for flight with unreliable airspeed indication in every line aircraft's QRH.

 

[Urwumpe]

Your previous post to this was on the right track. Power and attitude equals airspeed. Know the numbers. There is a procedure for flight with unreliable airspeed indication in every line aircraft's QRH.

Power, attitude, pressure altitude, temperature, weight, ...

Sorry, but this is just stupid. There is no such rule for a complete loss of the air data reference system. In no jetliner handbook.

How the real rules look like: http://www.smartcockpit.com/plane/airbus/A330/

What you do is quickly establishing a throttle and attitude setting for stable flight under normal conditions. Now try the same in a thunderstorm. There is no universal rule for getting the speed from attitude and power, you get the power and attitude so the plane remains inside a stable region.

You should better read the preliminary accident report, because it already shows great how thick the situation for the pilots already was by what is known to us.


EDIT:

From the Flight Crew Training Manual for the A330/A340:

Two ADR outputs are erroneous but different and the remaining ADR
is correct, or if all three ADR outputs are erroneous but different. The
AP and A/THR will disconnect. If the disagreement lasts for more than 10
seconds, the PRIM triggers the NAV ADR DISAGREE ECAM caution.
Flight controls revert to ALTN 2 law. The SPD LIM flag is displayed on
both PFDs, however VLS and VSW are not displayed. This condition is
latched until a PRIM reset is performed on ground without any hydraulic
pressure. However, if the disagreement was transient, the AP and A/THR
can be re-engaged when the NAV ADR DISAGREE message has
disappeared.

...

However, in very extreme circumstances, two or all three ADRs may provide
identical but erroneous data. If there is any doubt, then do not instinctively reject
the outlier ADR, although the temptation may exist if the other two ADR outputs
are consistent. In most cases, this decision would be correct, but not in the case
where two speed/altitude indications are consistent but wrong. Apply the initial
actions of the UNRELIABLE SPEED INDICATION QRH procedure from memory
as they quickly provide a safe flight condition in all phases of flight and aircraft
configuration. Rely on the primary flight parameters of pitch attitude and thrust
setting.
Because the displayed information may be erroneous, the flying accuracy cannot
be assumed. Incorrect transponder altitude reporting could cause confusion.
Therefore, declare a MAYDAY to advise ATC and other aircraft of the situation.
Reference to the QRH should only be made when a safe flight path has been
established. The QRH provides pitch attitude and thrust settings for each flight
phase and for different weights.
After applying the QRH procedure, and when the aircraft flight path is stabilised,
attempt to identify the faulty ADR(s). Once the faulty ADR(s) has/have been
positively identified, it/they should be switched OFF. This will trigger the
corresponding ECAM procedure, which should be applied.

 

[garyw]

Sorry, but this is just stupid. There is no such rule for a complete loss of the air data reference system. In no jetliner handbook.

http://luckybogey.wordpress.com/200...-330-unreliable-airspeed-problems-since-2006/

Refers to The Volume 3 of the FCOM and QRH provide the UNRELIABLE SPEED INDIC / ADR CHECK PROC procedure.

 

[Urwumpe]

http://luckybogey.wordpress.com/200...-330-unreliable-airspeed-problems-since-2006/

Refers to The Volume 3 of the FCOM and QRH provide the UNRELIABLE SPEED INDIC / ADR CHECK PROC procedure.

yes. Also see the edits in my post. There is as you can also read in your link, no way to use attitude and thrust for setting a desired speed or calculate speed from attitude and thrust. It has such references for establishing stable flight in such a situation. With huge possible speed variations.

BTW: Kudos for finding the proper homepage to give me the concluding quote on the matter:

We, like the BEA, have almost approached a conclusion. What we need now is to understand why our colleagues flying the AF477 were unable to get the aircraft out of the mess. After consulting the pilots that have been faced with these same Pitot issues, we realize that a large amount of immediate judgement is needed to overcome the multiple alarms, in a very little time. The cockpit crew must execute long check-lists and procedures, complex and even somewhow contradictory… By night, in manual flight, without any speed reference, with the probable loss of attitude, and partial stand-by instruments… Only a donkey could state in public that a simple hold of «pitch and power» could be enough to solve the problem.

 

[ex-orbinaut]

Amusing. :lol:




Freshly scanned... Hello? Thought that did not exist in ANY commercial aircraft QRH? Why is it in mine?

That's all. Thanks for the A330 info, too.

 

[Urwumpe]

Freshly scanned... Hello? Thought that did not exist in ANY commercial aircraft QRH? Why is it in mine?

Maybe you didn't read it properly - it is no "thrust+attitude = speed" equation, but a coarse way of keeping the plane flying at all while the crew sorts out the problem. It is no replacement of the ADR.

(Of course, I maybe read this a bit too much as metrologist, but if the variation around an average airspeed is almost as big as the safe range for flying, I think it is doubtful to say that you control airspeed with it.)

 

[ex-orbinaut]

it is no "thrust+attitude = speed" equation,

Ah, okay. I see where your gripe is. My phraseology.... Apologies.

(Of course, I maybe read this a bit too much as metrologist, but if the variation around an average airspeed is almost as big as the safe range for flying, I think it is doubtful to say that you control airspeed with it.)

Actually, it is surprisingly more accurate than you might initially think. Don't forget, the thrust is opposing the drag, and they look for an equilibrium. The given thrust settings are above the very low end of the power to drag curve, so you don't get caught on the backside of it. For a given weight this method will result in a (very) reasonably predictable airspeed or mach number, from PA-18-150's to B737-200's. I won't speak for anything I have not had any experience in.

This is not a complete essay on the subject, so I am not bringing into it the lift : drag relations that exist in non level flight, nor the transient variations that turbulence causes, much less thunderstorms. The main focus of that particular training is AVOIDING them!!!

I stand meticulously corrected, and, yes, maybe I do need glasses!:lol:

 

[Urwumpe]

Come on, I am sure the A-10 QRH does even have tables for "one wing missing, two wings missing, airspeed dial shot away". :lol:

Also, if I am not completely wrong with the mathematics, the temperature dependency of the engine thrust should be stronger than the effect of it on drag or indicated airspeed.

 

[ex-orbinaut]

Come on, I am sure the A-10 QRH does even have tables for "one wing missing, two wings missing, airspeed dial shot away". :lol:

Don't know anything about that, but I shouldn't wonder that the checklist reads something like...

Conditions >
Both wings missing:
Massive loss of altitude:

Actions >
1. Eject Handle Locate and grasp firmly
2. PULL IT! Waiting for a special invite? I said PULL IT!
3. Checklist Complete

Also, if I am not completely wrong with the mathematics, the temperature dependency of the engine thrust should be stronger than the effect of it on drag or indicated airspeed.

No, your not wrong. The data is tabulated in temperature dependent EPR tables, and include corrections for different conditions.

 

[Linguofreak]

Don't know anything about that, but I shouldn't wonder that the checklist reads something like...

Conditions >
Both wings missing:
Massive loss of altitude:

Actions >
1. Eject Handle Locate and grasp firmly
2. PULL IT! Waiting for a special invite? I said PULL IT!
3. Checklist Complete

It's probably not on any official checklist, but there is an Israeli pilot that managed to land an F-15 with one wing after a collision during a training accident. (Actually, he hadn't seen the missing wing, and said that if he had, he would have ejected).

 

[Evil_Onyx]

It looks like some more wreckage has been found.

http://www.bbc.co.uk/news/world-europe-12953432

Wreckage from an Air France jet lost over the Atlantic nearly two years ago with 228 people on board has been found, French investigators say.

 

[Turbinator]

Presentation: http://www.bea.aero/fr/enquetes/vol.af.447/point.presse.4avril2011.pdf

 

[N_Molson]

Here they are. Let's hope the flight recorders survived the immersion at 3000-4000 meters below the sea level...

 

[Urwumpe]

It's really fantastic what the new Remus 6000 AUVs can do And that without umbilical cables.

http://www.hydroidinc.com/remus6000.html

These had been borrowed from the GEOMAR research institute BTW, are their newest toys, this one was the "AUV Abyss":

http://geomar.de/index.php?id=537&tx_ttnews[tt_news]=721&tx_ttnews[backPid]=1&cHash=fb05a18b54

http://www.ifm-geomar.de/index.php?id=auv

For recovering debris pieces and maybe the black boxes, the ROV Kiel 6000 of GEOMAR or the ROV Victor 6000 of the French Ifremer will be used.

 

[Keatah]

Sure, the flight recorders should be just fine. Solid-state or mechanical. They're built pretty tough.

Now as far as pitot tubes failing. Well, all you need is to have a sufficient heating system. If we're still having icing problems with those after 100 years of usage then the industry needs to re-think the design. AND stop the cost cutting measures.

Now as far as getting an airspeed measurement with three blocked pitot tubes. Why not use the rat as a rough indicator. equip them with dynamic braking systems and measure airflow by noting rpms and air density and how much power and braking is needed to maintain those rpms.

What about an emergency pitot tube that is shielded inside the body of the plane and popped open when needed? Fresh and new. ready to roll! What about simple mechanical analogue of the pilot sticking his hand out the window. A door that opens and depending how much pressure is needed to force it open tells you how fast the plane is going. Put several of them around the fuselage and you can now get an idea of what the "angle of attack" is. use enough and you can get a 360* picture..

heh, it would seem if 3 pitot tubes are reading zero and the plane was just flying at 40000 ft and the engines are running full bore, AND the rat is working. Well that is enough info to tell me the 3 pitot tubes are messed up. Ignore them.

At a specific power setting, internal temp, and gas velocity, and airspeed in and out of the engine -- AND including density, altitude, previous known speed, gps speed, you could compute an approximate air speed. Basically you're looking at how much traction the engines are getting.

Also, determine airspeed by responsiveness of the craft. At high speeds you need little deflection in control surfaces, at low speeds you need more. Apply x amount of deflection and measure inertial changes in the craft.

As a bonus you can figure out the attitude you are in by having kept a recent trend AND computing how the plane may behave as the trajectory develops. All along the way, measuring changes in the INS with with is expected and and what is really happening.

They have already done much of this in the lab. And you can even have loss of all control surfaces, there is software available (but not in use) that will control the engines to vary the power applied to climb and dive and turn. This would really only work on a 2,3,4 or more engine craft.

Lotsa stuff that can be done, but isn't due to cost cutting.

---------- Post added at 10:49 PM ---------- Previous post was at 10:22 PM ----------

http://www.spiegel.de/international/world/0,1518,druck-679980,00.html

The print version, without the distracting advertisements. Absolutely fascinating to read. I always felt that airbus' planes are too complex for pilots. And now we have all these control laws the come into play at various phases of the flight. And in an emergency situation the last thing a pilot needs is a plane that stubbornly refuses to behave itself and be cool. Even worse, the various a-laws and u-laws change the behavior of the aircraft too much. A pilot doesn't need his plane taking on different personalities. Some of which he is probably not familiar with or expecting. Yeh.. Too much electronic stuff fighting against the pilot. Keep it simple. Fly Boeing!

---------- Post added at 11:00 PM ---------- Previous post was at 10:49 PM ----------

I think that if we need to have our jets fly so damned efficiently at such extreme altitudes of 40,000ft and more then we need to have more reliable, NOT MORE COMPLEX control systems and computers. If the complexity increases as the square of performance/efficiency, as it seems to be doing these days, then we need to stop and re-evaluate just how far they wanna push the industry. Perhaps for my next trans-pacific flight I'll get a bush pilot and a steamguage bi-plane or something.

---------- Post added at 11:02 PM ---------- Previous post was at 11:00 PM ----------

And one more thing, all too often you keep hearing of pilot schedules and pressure from airlines and time and costs, that all put together lead up to accidents. For chrissakes lay off it for a while!!!

 

[Urwumpe]

Keep it simple. Fly Boeing!

Can you answer the question, what would have happened to a Boeing with FBW in the same situation? For example a Boeing 777 - which is until today the only Boeing with FBW?

Your rant is nothing new there, Boeing pilots always rant about Airbus cockpits and the other way around almost since Airbus started including FBW.

As far as I understand the Boeing schematics, the same accident cause (all pitot tubes failed) would result in the same trouble. Especially in the same situation, of being above or between a strong thunderstorm system.

The important information is: We are not talking about limits or automatic behavior. We are talking about important flight state data not being available. The human pilot of a Boeing 737 would be in the same dilemma now as the human pilot of a A330.

The only point where a Boeing 777 starts to differ in behavior from the A330 is when you test the limit protection. The 777 has only soft limits and will happily let you ruin the aircraft, if you want to. The A330 has hard limits, that are usually active unless the pilot presses a switch on the flight stick.

But in both cases, the limit protection would have been already disabled by the loss of air data - which happened on the Airbus as we know by the radio messages. And all crews would be aware of it. Even on a Boeing, where the limit protection is just a formality, the crew will get a warning that the control laws degraded. Even on a 777, there will be a change in how the joystick deflection results in aircraft motion.

On all Boeing planes except the 777, the situation would have been equally bad - the pilots don't know airspeed and altitude themselves, the autopilot hopefully switched off and the crew has to stabilize the aircraft during a thunderstorm with changing wind. It is pretty likely that a human pilot would have ended in the same stall and rapid loss of altitude.

That the A330 aircraft wreck was found a long distance from the initially suspected impact location and far away from the point of the last message suggests, that the crew managed to stabilize the plane, but eventually lost the battle against the thunderstorm around them. That information did not get included in the Spiegel Online article, it was written directly after the crash. The initial sequence of events might still be right, but the last minutes of flight not - the plane did get stabilized before impact. Maybe it was already climbing, when it stalled again and crashed. We will know soon.