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AirAsia QZ8501 - Another missing flight!

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Re: AirAsia QZ8501 - Another missing flight!

Postby Strong Eagle » Mon, 05 Jan 2015 3:37 am

aster wrote:Definitely taking the A380 on my next flight though... always feel better on big planes, just like I feel safer at sea on big cruiseliners.


All commercial jetliners are able to withstand rather extreme stresses without fear of frame fractures like a wing coming off. Structural issues are a very small percentage of total aircraft incidents. Those structurally related crashed that did occur were the result of metal fatigue incurred after thousands of cycles, and those are now carefully inspected.

Boeing has published some interesting statistics at http://www.boeing.com/news/techissues/pdf/statsum.pdf

47% of fatal accidents occur during final approach and landing.

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Re: AirAsia QZ8501 - Another missing flight!

Postby aster » Mon, 05 Jan 2015 9:10 am

Exactly, it's quite uncommon to lose a plane at this stage of a flight.

I think what we witnessed was not so much a general structural issue based on wear and tear (as just as you mentioned planes are built and expected to withstand enormous stress throughout their life-span), but rather extreme effects that the atmospheric conditions had exerted on the plane in terms of changing its altitude and throwing it about like a paper cup in a wind storm. Those sudden changes in altitude, especially being pulled up so quickly to such heights, before being dropped, I just didn't think it could happen to a jetliner. In a worst-case scenario an air vortex/updraft of two joining thunderstorms can take a paraglider against their will to 10k metres above and then drop them like a rock, but a passenger plane?

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Re: AirAsia QZ8501 - Another missing flight!

Postby martincymru » Mon, 05 Jan 2015 9:41 am

No incentive to invest in cross border weather monitoring and prediction.

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Re: AirAsia QZ8501 - Another missing flight!

Postby rajagainstthemachine » Mon, 05 Jan 2015 10:09 am

nanana wrote:
rajagainstthemachine wrote:I have to fly back to Singapore on 3rd from Thailand on tiger. Wish me well. Although I've been flying almost every month for the last ten years, I can't help feeling a bit nervous, I've checked all the weather systems along the flight path just to calm me down.
Downside of dying budget: They don't serve drinks, at least one wont be in the senses in case calamity strikes.


Safe trip back, rajagainstthemachine.


Thank you nanana. :D, flew back to Singapore safe and sound on Tiger.
To get there early is on time and showing up on time is late

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Re: AirAsia QZ8501 - Another missing flight!

Postby x9200 » Mon, 05 Jan 2015 11:41 am

aster wrote:Exactly, it's quite uncommon to lose a plane at this stage of a flight.

I think what we witnessed was not so much a general structural issue based on wear and tear (as just as you mentioned planes are built and expected to withstand enormous stress throughout their life-span), but rather extreme effects that the atmospheric conditions had exerted on the plane in terms of changing its altitude and throwing it about like a paper cup in a wind storm. Those sudden changes in altitude, especially being pulled up so quickly to such heights, before being dropped, I just didn't think it could happen to a jetliner. In a worst-case scenario an air vortex/updraft of two joining thunderstorms can take a paraglider against their will to 10k metres above and then drop them like a rock, but a passenger plane?

I don't expect a structural damage neither but I guess the mentioned earlier icing alone can bring the plane down. If the plane was lifted up by a few thousand feet in a matter of seconds this has to be a force to reckon with, and probably lots of water at the attitude where normally you may have -60C or lower. Also not sure if such extreme weather (displacement of air masses) may lead to a stall and once this happened with again high speed wind I don't think it would be a piece of cake to get the plane recovered.

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Re: AirAsia QZ8501 - Another missing flight!

Postby ecureilx » Mon, 05 Jan 2015 3:06 pm

aster wrote:
x9200 wrote:If correct it seems to suggests an extreme weather afterall.


Seems like it right now, even though it is extremely rare to lose a plane due to atmospheric conditions at this stage of the flight. Still surprised that not a single word was uttered via the radio... I guess we'll have to wait until the flight recorders are recovered to learn more about what happened.

Definitely taking the A380 on my next flight though... always feel better on big planes, just like I feel safer at sea on big cruiseliners.


If I recall, aviators are taught to "AVIATE, NAVIGATE and finally, COMMUNICATE"

If a situation develops, figuring out the nearest Traffic control's frequency should not the top of the priority, I understood !

btw, if the plane disintegrated, the ELTs would have been triggered automatically, sending out coordinates of the crash.

X9200, in the early stages of Airbus' full FBW, they had some issues, where the software decides how the plane should fly, based on inputs of the rest of the system, and 'apparently' there was some hair raising moments.

And atleast on one crash, Airbus described the software logic, that is pretty mind boggling

Like, for the auto brake to kick in, there has to be some amount of weight detected on the landing gears, and if not, the plane will not start to brake, for example, to prevent in flight deployment of brakes etc. and that was after the TAM crash, such reading was public

I too read of massive downdrafts or updrafts in South Asian skies, that could have done unexpected damage

Though the numerous ships and equipment means there will be a closure sooner !

BTW, I saw Indonesia has gone on their own blame game, saying the flight was not authorised .. yah right ..

PS, Russia sent in a BE 200 - http://en.wikipedia.org/wiki/Beriev_Be-200

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Re: AirAsia QZ8501 - Another missing flight!

Postby x9200 » Mon, 05 Jan 2015 5:05 pm

I also found it plain stupid to put the weight on the lack of authorization as it was a root cause of some sort. And also yes to the potential software issues. Specifically for the autopilots airbus seems to have many of them. I mean, not really issues but sort of counter-intuitive behavior, formally documented in the manuals but often not realized by the crew and contributing to the reasons for the disaster. I recall at least two cases like that including the mentioned AF447.

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Re: AirAsia QZ8501 - Another missing flight!

Postby aster » Mon, 05 Jan 2015 10:04 pm

Yes, blaming things on whether the plane was allowed to fly on that day of the week is ridiculous. In fact it doesn't shed bad light on Air Asia but instead diffracts it upon Indonesia itself. How is a plane allowed to officially check-in passengers at a major airport and take off... if it shouldn't be flying on that day? Hmmm...

As far as Airbus controls are concerned, the whole autopilot software thing is an old issue and Boeing has had similar issues with both the Dreamliner and the ol' 747 doing rollercoaster maneuvers due to software issues. The real problem with Airbus is the modern control setup with "joysticks." These are not physically linked so technically each pilot can be doing his own thing, but what's WORSE... they have no clue what the other person is doing. The system has various settings, I believe one allows for an override whereas another simply averages out the inputs of both pilots. Either way, this is not an ideal setup and the old style yokes that Boeing employs are better. This way everything is clear and both pilots are always on the same page.

For readers of Popular Mechanics here is a must-read article about the Air France flight that departed from Brazil and never made it across the pond:

http://www.popularmechanics.com/technol ... 47-6611877

Do note that there is a PAGE 2 with the link hidden below some youtube video.

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Re: AirAsia QZ8501 - Another missing flight!

Postby ecureilx » Mon, 05 Jan 2015 10:50 pm

aster wrote:As far as Airbus controls are concerned, the whole autopilot software thing is an old issue and Boeing has had similar issues with both the Dreamliner and the ol' 747 doing rollercoaster maneuvers due to software issues. The real problem with Airbus is the modern control setup with "joysticks." These are not physically linked so technically each pilot can be doing his own thing, but what's WORSE... they have no clue what the other person is doing. The system has various settings, I believe one allows for an override whereas another simply averages out the inputs of both pilots. Either way, this is not an ideal setup and the old style yokes that Boeing employs are better. This way everything is clear and both pilots are always on the same page.


then again, I am not aviation person, but I believe Boeing too went AB way, there are no cables anymore from the control yokes, and Airbus has some tactile feedback or something

then again, the common humourous advantage of the Airbus is the pilot can have his meals and coffee without worrying about spilling it :D

like this !!

Image

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Re: AirAsia QZ8501 - Another missing flight!

Postby Strong Eagle » Mon, 05 Jan 2015 11:54 pm

ecureilx wrote:then again, I am not aviation person, but I believe Boeing too went AB way, there are no cables anymore from the control yokes, and Airbus has some tactile feedback or something


The 777 was the first Boeing fly by wire aircraft. Subsequent to its introduction, Boeing introduced 'next gen' aircraft in various lines that also went to fly by wire. The 737-600 and subsequent models are all fly by wire.

The 747-400 was not fly by wire but the 747-8 is. It's a much better system than a mechanical system for a variety of reasons.

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Re: AirAsia QZ8501 - Another missing flight!

Postby aster » Tue, 06 Jan 2015 12:38 am

The whole fly-by-wire thing doesn't change anything from a navigational standpoint. Today's cars like those big SUVs are fly-by-wire technology too when it comes to the gas pedal. It simply means that there is no physical wire going from the gas pedal to the engine itself.

The yokes on Boeing's planes are still interconnected, and I would be willing to bet that this connection is still completely physical.

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Re: AirAsia QZ8501 - Another missing flight!

Postby ecureilx » Tue, 06 Jan 2015 1:32 am

aster wrote:The yokes on Boeing's planes are still interconnected, and I would be willing to bet that this connection is still completely physical.


if you mean that the new Boeing's are not totally dependant on wires to fly, you are wrong there .. ;) ;)

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Re: AirAsia QZ8501 - Another missing flight!

Postby x9200 » Tue, 06 Jan 2015 8:33 am

As much as I understand it, the Airbus "joystick" controls do not provide any visual feedback of the change that was just introduced with them. For example (probably gross simplification) you press it once, the stick goes back to the original position, the plan starts to climb and that's it. In old fashion controls you would see from the controls that the plane is/may be climbing similar way you see from the position of the bicycle's handlebar it's turning left or right. Now, I understood that Boeings also have electronic controls (I see still the yokes) but they do not spring back or indicate some other way that the plane was given the climb command.

Of course whether the plane is climbing or not is visible from the instruments (i.e. horizon) but in the stress situation such additional visual information may be critical.

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Re: AirAsia QZ8501 - Another missing flight!

Postby Strong Eagle » Tue, 06 Jan 2015 9:07 am

x9200 wrote:As much as I understand it, the Airbus "joystick" controls do not provide any visual feedback of the change that was just introduced with them. For example (probably gross simplification) you press it once, the stick goes back to the original position, the plan starts to climb and that's it. In old fashion controls you would see from the controls that the plane is/may be climbing similar way you see from the position of the bicycle's handlebar it's turning left or right. Now, I understood that Boeings also have electronic controls (I see still the yokes) but they do not spring back or indicate some other way that the plane was given the climb command.

Of course whether the plane is climbing or not is visible from the instruments (i.e. horizon) but in the stress situation such additional visual information may be critical.


From the Pprune forums:

Regarding how they work, IIRC when both sticks are used at the same time, the algebraic sum of the movements is used. So if one pilot pulls it fully back, and one pushes it fully forward, they cancel out and nothing happens. There is obviously some complex maths used to determine where the plane goes when receiving two different inputs.

There is also a priority button, which when pressed gives that pilot priority and stops the other stick from working... unless the other pilot also presses for priority in which case the last person to press has priority (I think). There is some kind of warning alarm which sounds saying "Priority Right/Left" when someone presses for priority.

EDIT: A lot of people blamed the crash of AF447 on the asynchronous side sticks, but it was just a small contributing factor. Like I said Airbus designed it with alarms to make it clear who actually has priority - the pilots on AF447 failed to notice they both pressed for priority.

Still, that's no excuse to not have the sidesticks synchronised. To this day I still cannot figure out why Airbus would design them like that.

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Re: AirAsia QZ8501 - Another missing flight!

Postby the lynx » Tue, 06 Jan 2015 9:24 am

aster wrote:Yes, blaming things on whether the plane was allowed to fly on that day of the week is ridiculous. In fact it doesn't shed bad light on Air Asia but instead diffracts it upon Indonesia itself. How is a plane allowed to officially check-in passengers at a major airport and take off... if it shouldn't be flying on that day? Hmmm...

As far as Airbus controls are concerned, the whole autopilot software thing is an old issue and Boeing has had similar issues with both the Dreamliner and the ol' 747 doing rollercoaster maneuvers due to software issues. The real problem with Airbus is the modern control setup with "joysticks." These are not physically linked so technically each pilot can be doing his own thing, but what's WORSE... they have no clue what the other person is doing. The system has various settings, I believe one allows for an override whereas another simply averages out the inputs of both pilots. Either way, this is not an ideal setup and the old style yokes that Boeing employs are better. This way everything is clear and both pilots are always on the same page.

For readers of Popular Mechanics here is a must-read article about the Air France flight that departed from Brazil and never made it across the pond:

http://www.popularmechanics.com/technol ... 47-6611877

Do note that there is a PAGE 2 with the link hidden below some youtube video.


Are you talking about video link in Page 2 or 1? I could only find the video in Page 1. Not sure if it is the video you're talking about...


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