Qantas computer glitch?

[unussapiens]

That is correct on most older aircraft. However newer aircraft are fly-by-wire ie they are flown by a computer and controlled using a joystick, almost exactly (in operation) like a normal PC joystick. Also there is the nav equipment that all planes have.

I think he meant that the control signals were sent via electrical wires.

 

[Moonwalker]

As usual, speculations/gossip factory becomes alive. To trust passenger reports is something journalists love to do and people like to listen/read. But it's not the very best choice to learn what was going on in detail, especially when something like an altitude drop happened. Passengers often unconsciously tend to exaggerate situations and partly don't know anything really.

Also, although it was a joke I guess, I would like to mention that neither Airbus nor Boeing (or any other) aircraft use any kind of windows software for its flight control computers or another parts of systems.

Concerning the safety of Qantas:

it is the only one oldest large airline which until today had no loss of any of its jet aircraft, after they had a loss of 63 people until 1945 (which wasn't something special in the propeller aircraft age) and losses of two aircraft until 1960 but without losses of lifes.

One or two incidents doesn't mean that an airline has become more unsafe or that maintenance standards have changed. The German Lufthansa had more incidents, accidents and losses which doesn't mean that Lufthansa is an unsafe airline or had become more unsafe.

The last incident on Qantas before the current two incidents was almost 10 years ago by the way.


-----Posted Added-----

However newer aircraft are fly-by-wire ie they are flown by a computer and controlled using a joystick, almost exactly (in operation) like a normal PC joystick. Also there is the nav equipment that all planes have.

Not each newer aircraft uses fly-by-wire and a sidestick. This is only a signature feature for any Airbus aircraft past the A300/A310 series. All Boeing aircraft (and most other too), old and new, still don't use fly-by-wire, while the usual control columns are still prefered by Boeing too (but any newer aircraft are flown by flight management computers indipendently of fly-by-wire). That's why I prefer and love Boeing much more than Airbus. It's still classic and not too much gimmick

 

[tblaxland]

An update: http://www.abc.net.au/news/stories/2008/10/14/2391134.htm

The plane was cruising at 37,000 feet when a fault in the air data inertial reference system caused the autopilot to disconnect. But even with the autopilot off, the plane's flight control computers still command key controls in order to protect the jet from dangerous conditions, such as stalling, the ATSB said. "About two minutes after the initial fault, (the air data inertial reference unit) generated very high, random and incorrect values for the aircraft's angle of attack," the ATSB said in a statement. "These very high, random and incorrect values of the angle attack led to the flight control computers commanding a nose-down aircraft movement, which resulted in the aircraft pitching down to a maximum of about 8.5 degrees."

 

[Moonwalker]

An update: http://www.abc.net.au/news/stories/2008/10/14/2391134.htm

It seems that there were issues with the gyroscopes of the IRS. That's why I don't like Airbus. For most Boeing aircraft such an IRS failure wouln't have an effect to the flight control computers as soon as the autopilot is disconnected, because there is no automatic stall and speed protections comparable to the ones of Airbus. Too bad when the crew is less able to interact with the systems.

 

[Urwumpe]

The IRS does not measure AOA. That is done with the pitot tube. A clogged pitot tube has already destroyed uncountable Boeings.

 

[Moonwalker]

The IRS does not measure AOA. That is done with the pitot tube.

Not on Boeing and Airbus aircraft. The AOA is measured by the angle air flow sensor or also called angle of attack probe.

Beside the AOA probe data, laser gyroscopes also provide data to the ADIRU's. There are two AOA probes, one on each side of the forward fuselage. On the A330, the pilot AOA probe is connected to ADIRU 1 while the first officer AOA probe is connetced to ADIRU 2 (while ADIRU 3 is not connected to any AOA probe).

A clogged pitot tube has already destroyed uncountable Boeings.

I know one case (but it was the static port, not the pitot tube). There might be a few more but certainly not "uncountable". Also, clogged pitot static systems are a general issue in aviation, not only for heavy Boeing aircraft.

 

[tblaxland]

Also, clogged pitot static systems are a general issue in aviation, not only for heavy Boeing aircraft.

I think that was Urwumpe's point - that Boeing is no better or worse than any other aircraft in this regard.

Re automatic speed/stall protections, there is a whole class of safety measures that could be considered detrimental to normal operations due to false positives. Another example demonstrated at the Motor Show here recently - automatic safety brakes on vehicles. What if this system malfunctions on the Autobahn and you end up with a end up with another car plowing into the back of you at 200km/h? It is hard to say whether these systems are good or bad overall.

 

[Moonwalker]

I think that was Urwumpe's point - that Boeing is no better or worse than any other aircraft in this regard.

Right. I personally just don't like computer controlled pitch, roll and speed protection systems. Also some real pilots don't like such systems. Of course this doesn't mean that Boeing aircraft are better or more safe. But in a certain case such computer controlled systems can become an issue.

For the sake of flying heavy passenger aircraft in MS FS, I always stick with Boeing (as I would do in case I would be a real pilot, since flying an Airbus is pretty boring) especially the 767-300ER

 

[tblaxland]

For the sake of flying heavy passenger aircraft in MS FS, I always stick with Boeing (as I would do in case I would be a real pilot, since flying an Airbus is pretty boring) especially the 767-300ER

I think if I had the opportunity to be a real pilot I would fly anything they would give me

 

[Moonwalker]

I think if I had the opportunity to be a real pilot I would fly anything they would give me

Not my whole life

But it actually depends if you are interested in flying/being a pilot generally, or if you are interested in certain systems/cockpit layouts and airplane types (I personally don't like Airbus flightdecks at all). A lot of pilots actually choose their type rating.


-----Posted Added-----

http://www.atsb.gov.au/newsroom/2008/release/2008_43.aspx

 

[joeybigO]

Having experience at both. I would have to say that flying the real thing is not so much more difficult, however it is a whole bunch more to understand before you ever go V1. The sims don't spend enough time with the true realisms of flight. Most anyone can start a 777 but can they start a 737-200?

 

[Moonwalker]

Having experience at both. I would have to say that flying the real thing is not so much more difficult, however it is a whole bunch more to understand before you ever go V1. The sims don't spend enough time with the true realisms of flight.

Do you mean the complexity/physics of desktop sims or the physics of real sims?

In case you are referring to complexity and procedures of desktop sims:

http://www.dreamfleet2000.com/Previews/727/preview_2D.html

http://www.leveldsim.com/sevensix_screenshots.asp

http://atr.flight1.net/

Most anyone can start a 777 but can they start a 737-200?

Do you mean engine start?

An engine start of the 737-200 is not that much different to a 777 really. With the air cond packs off, providing enough bleed air pressure (either from the APU or external source) you just have to use the corresponding engine start switch and set the fuel control lever to run as soon as the engine reaches a certain N2 rpm (about 20%). This doesn't differ a lot to the 777, beside that todays engine start switches are spring-loaded and also used for continuous ignition. The only thing which is more complicated on the the old 727 series for example is the management of the electrical system (and fuel system as well). You have to connect the buses and manage its frequencies manually which is done by the flight engineer anyway, and the engine start too.

But all this just is nothing compared to the Concorde or the old 747-100 to 300 series, which really required a flight engineer aboard

But even this can be done by one person, at least using a desktop sim

http://www.flusiforum.de/reviews/includer.php?site=pssconcorde

http://www.avsim.com/pages/0806/SST/SST.htm

 

[tblaxland]

http://www.avsim.com/pages/0806/SST/SST.htm

Damn, a virtual toilet on that Concorde, now that is detailed!

 

[tl8]

At 263 Meg, it would want to be!

 

[James.Denholm]

...which resulted in the aircraft pitching down to a maximum of about 8.5 degrees.

Talk about media over-hyping things! I saw the news a couple of nights ago, which had an animation of the event, you know, to help the public visualise these things. The animation showed the plane's nose dropping down to about 70 degrees! That's nuts!

Though, if there's one thing to take away from this, a lesson to be learned, it's that the airlines tell you to keep your seatbelt on while in flight regardless of the flight's stage for a reason.

 

[AstroCam]

Two things: One, Channel 7 really over emphasises the negative and lays on the BS with a shovel. Today tonight anyone? sick. And Two, i always leave my seatbelt on during the flight.

Oh, and three. For the sake of argument, has anyone else here managed to clog an airline toilet? Cause i have , back in 2000.

Finally a quick fact. According to the Australian broadcasting code of practice, current affairs shows (ACA, Today Tonight), etc) do not have to present a balanced argument, and they can legally make up the entire story if they so desire.
Sucks don't it?

 

[Moonwalker]

Damn, a virtual toilet on that Concorde, now that is detailed!

Certainly not a critical feature. But it's nice eye candy. Complete aircraft interiors are standard for professional flight simulation meanwhile (beside highly detailed systems simulation of course)

 

[Urwumpe]

Not on Boeing and Airbus aircraft. The AOA is measured by the angle air flow sensor or also called angle of attack probe.

Beside the AOA probe data, laser gyroscopes also provide data to the ADIRU's. There are two AOA probes, one on each side of the forward fuselage. On the A330, the pilot AOA probe is connected to ADIRU 1 while the first officer AOA probe is connetced to ADIRU 2 (while ADIRU 3 is not connected to any AOA probe).

I know one case (but it was the static port, not the pitot tube). There might be a few more but certainly not "uncountable". Also, clogged pitot static systems are a general issue in aviation, not only for heavy Boeing aircraft.

Yes, but still the AOA can only be accurately measured by dynamic pressure sensors. A pure inertial reference system, which can drift by up to 0.32° over a 16h flight is pretty inaccurate, when the range of practically legal AOAs is between -1° and +5°.

The pure inertial calculation would be used, when both air data probe measured values are considered wrong. This could, when your description of the A330 air data system is correct, already happen when one Air data probe is clogged and the inertial reference of the third unit being closer to the wrong air data probe (with the intact air data probe being considered the erroneous reading)
First it rules out the intact probe and flags it as damaged, as the damaged air data probe is closer to the inertial measurement.

Now, you just have to make sure, that the pure inertial reference is flagged faulty. That both air data probes at the same time fail and you have to use inertial can also happen, but the inertial is then rarely wrong by about 10°.

Re automatic speed/stall protections, there is a whole class of safety measures that could be considered detrimental to normal operations due to false positives. Another example demonstrated at the Motor Show here recently - automatic safety brakes on vehicles. What if this system malfunctions on the Autobahn and you end up with a end up with another car plowing into the back of you at 200km/h? It is hard to say whether these systems are good or bad overall.

Well, I am from the mind set closer to the Airbus doctrine of letting the aircraft control it's limits itself, with the pilot being able to override (with a single press of a red button on his stick BTW).

On your car example: An emergency braking from 200 km/h would be annoying, but not deadly. When somebody plowed into your back then, it is his fault of violating road traffic laws (safety distance and/or medical state and/or technical safety). You can't blame the emergency brake on your car then, but rather the lack of one on the other car.

But still, if your car has an override button to allow you to abort the automatic emergency brake, you would have enough time to react. For the same reason, with our natural distrust of technology, all cars I know allow disabling the ESC, even though the system is meant for increasing safety. But especially early version of can be worse in extreme situations.

It is like the cruise control switch. If you know what it does and what it's limitations are, you are a good driver. If you enable it and go to the back of the caravan to make a coffee, you are a very very bad driver.

 

[Moonwalker]

@Urwumpe,

The AOA is one thing. Beside that one value, the IRS provides further reliable information such as bank and pitch angle informations as well as heading. In case of the Qantas A330 it was an IRS fault which is part of the air data inertial reference unit and resulted in an autopilot disconnect. But the stall warning and attitude loss on the pilots primary flight display could have been caused by faulty AOA probe measurements. Anyway, we have to wait for further details.

Here you go for the AOA probe locations and connections by the way:

Well, I am from the mind set closer to the Airbus doctrine of letting the aircraft control it's limits itself, with the pilot being able to override (with a single press of a red button on his stick BTW).

An Airbus pilot is not able to override the flight augmentation computer and its flight envelope protection just by pressing the red distinctive button on the sidestick. This button only disables the autopilot! The flight automation and flight envelope protection still remains active as this is part of the entire fly-by-wire concept of Airbus.

The flight augmentation computer always assures that the current bank and pitch angle is maintained automatically when releasing the sidestick (which springs back to its neutral position). You don't even need to use the rudder pedals for flying turns as this is done by the flight augmentation computer too. A bank angle of 67° is not exceedable in clean configuration, while it's 45° with flaps set. For a bank angle greater than 33° the pilot has to push the stick continuously, otherwise, when releasing the stick, the aircraft automatically returns to a maximum bank angle of 33° (while the autopilot, if engaged, generally commands bank angles not greater than 25°). The maximum pitch angle is 30° for climb and 15° in descent. The alpha protection automatically commands pitching as soon as the limts get exceeded.

With a faulty AOA measurement or IRS faults you can have such conditions on Airbus aircraft which just happened. That's what I don't like on Airbus.

 

[Urwumpe]

An Airbus pilot is not able to override the flight augmentation computer and its flight envelope protection just by pressing the red distinctive button on the sidestick. This button only disables the autopilot! The flight automation and flight envelope protection still remains active as this is part of the entire fly-by-wire concept of Airbus.

Limit protection and fly-by-wire are not the same. As far as I remember, there is a clear override switch on the sidestick, which is not only for the autopilot, but also for limit override.

Fly-by-wire is essentially just the control of the hydraulic actuators by electrical systems and state of the art in aircraft design today. It is true that you still need a minimal computer in the loop, but you don't need more than proportional deflection in the worst case.

Limit protection applies, when you have rate command or AOA command control loops.