Retrieving wreckage from AirAsia Flight To Singapore- no survivors recovered #3

[emirates1957]

Hello Emirates
Ive been meaning to ask you a question if you happen to know about the Pitot Tubes that we hear about.

If they are used to guage how fast air is moving through them or other calculations then doesnt the speed of the aircraft distort any measurements? I dont understand how the speed of the aircraft itself doesnt mess up measurements from them.

According to our Engineer if the pitot tubes freeze or let's say we're blocked by a bug on take off (highly unlikely), it is going to give you a false air speed. It doesn't mean the air speed actually changes. A procedure used is to maintain a certain altitude, attitude and power setting until the pitot clears. The pitot tube only gives you your speed. The speed of the AC will not distort measurements. All the Engineers feel very important at the moment....walking around with puffed out chests. So feel free to ask.

 

[emirates1957]

Hello Emirates
Ive been meaning to ask you a question if you happen to know about the Pitot Tubes that we hear about.

If they are used to guage how fast air is moving through them or other calculations then doesnt the speed of the aircraft distort any measurements? I dont understand how the speed of the aircraft itself doesnt mess up measurements from them.

According to our Engineer if the pitot tubes freeze or let's say we're blocked by a bug on take off (highly unlikely), it is going to give you a false air speed. It doesn't mean the air speed actually changes. A procedure used is to maintain a certain altitude, attitude and power setting until the pitot clears. The pitot tube only gives you your speed. The speed of the AC will not distort measurements. All the Engineers feel very important at the moment....walking around with puffed out chests. So feel free to ask.

 

[emirates1957]

Confirming all AC will have a rego under their wing.

 

[Hatfield]

According to our Engineer if the pitot tubes freeze or let's say we're blocked by a bug on take off (highly unlikely), it is going to give you a false air speed. It doesn't mean the air speed actually changes. A procedure used is to maintain a certain altitude, attitude and power setting until the pitot clears. The pitot tube only gives you your speed. The speed of the AC will not distort measurements. All the Engineers feel very important at the moment....walking around with puffed out chests. So feel free to ask.

I guess where I am getting confused is if those those tubes use wind that passes through them, then wouldn't a headwind VS a tailwind distort the calculations?

A car measures speed by RPMs (revolution per minute) of a physical thing like the wheel or axle turning, but if a plane is measuring speed by just wind passing through the tubes, then I dont understand how a strong headwind would make the plane seem to go faster than if it had a strong tailwind instead. Because the wind itself would register on the instrument.
Like even if the plane was standing still on the runway on a windy day, wouldnt those tubes register that it was moving a certain MPH because wind was passing through the tubes?

I obviously dont know how the tubes work. LOL

 

[emirates1957]

Confirming all AC will have a rego under their wing.

Gotcha...will check. I'm going to have to knock some wind out of their sails soon....they have never felt Sooo important !!!!

 

[emirates1957]

Okay...you have ground speed and air speed. If you have a head wind going through the pitot tubes it will show a reduction in the ground speed and obviously opposite for a tailwind. This does not change your indicated airspeed. It only changes the speed you are flying over the earth. Hope that makes sense Hatfield

 

[jggordo]

I have a question along those same lines. If the A/C runs into hail or ice and it causes the tubes to freeze, with the A/C on auto pilot would it not give a false speed to the auto pilot causing it to make false adjustments? Also if that were the case would it not give false information to the recorded data in the black box?

Just wondering if the false information could cause a "stall" ?

 

[Hatfield]

Okay...you have ground speed and air speed. If you have a head wind going through the pitot tubes it will show a reduction in the ground speed and obviously opposite for a tailwind. This does not change your indicated airspeed. It only changes the speed you are flying over the earth. Hope that makes sense Hatfield

That helps tremendously. I think I got it with that. In my non-aeronautical lamens terms......I think its something like this......The main importance for a plane is to have a certain air speed (i.e. air current going over the wing to generate lift). And so those tubes are an important element in measuring the speed of air passing through the tube (and also passing over wing).

A headwind or tailwind reduces or increases ground speed (which is the relationship of the plane to the ground) but it really has nothing to do with the speed of air passing over the wing.

A good analogy example is if there were hurricane force winds coming toward the plane, the plane could stay aloft and may hardly be moving forward at all. Huge air speed going over wing with little ground speed of plane moving.

Another example is we've all probably seen birds struggle to fly in a strong headwind and they can hardly get moving forward and sometimes give up and get swept off the side. Again huge air speed going over their wings but little ground speed going forward.

Or something like that LOL

 

[emirates1957]

That helps tremendously. I think I got it with that. In my non-aeronautical lamens terms......I think its something like this......The main importance for a plane is to have a certain air speed (i.e. air current going over the wing to generate lift). And so those tubes are an important element in measuring the speed of air passing through the tube (and also passing over wing).

A headwind or tailwind reduces or increases ground speed (which is the relationship of the plane to the ground) but it really has nothing to do with the speed of air passing over the wing.

A good analogy example is if there were hurricane force winds coming toward the plane, the plane could stay aloft and may hardly be moving forward at all. Huge air speed going over wing with little ground speed of plane moving.

Another example is we've all probably seen birds struggle to fly in a strong headwind and they can hardly get moving forward and sometimes give up and get swept off the side. Again huge air speed going over their wings but little ground speed going forward.

Or something like that LOL

Your doing really well, spot on.

 

[MsFacetious]

I have a question along those same lines. If the A/C runs into hail or ice and it causes the tubes to freeze, with the A/C on auto pilot would it not give a false speed to the auto pilot causing it to make false adjustments? Also if that were the case would it not give false information to the recorded data in the black box?

Just wondering if the false information could cause a "stall" ?

The answer to most of these is in the Air France 447 disaster. :twocents:

AirBus are much more "fly by wire" than other planes.
When something goes wrong the plane thinks it knows better than you do.
This makes it difficult to recover when the pitot tube freezes... because the plane believes the faulty reading.

http://www.telegraph.co.uk/technology/9231855/Air-France-Flight-447-Damn-it-were-going-to-crash.html

 

[emirates1957]

I have a question along those same lines. If the A/C runs into hail or ice and it causes the tubes to freeze, with the A/C on auto pilot would it not give a false speed to the auto pilot causing it to make false adjustments? Also if that were the case would it not give false information to the recorded data in the black box?

Just wondering if the false information could cause a "stall" ?

Yes is could create a stall. The auto pilot would be relying on information from the tube. One Engineer believes that there should be an auto disconnect from the auto pilot. I really need to speak to an A320 Pilot....will see what I can do. If the pitot is reading 200 kts the FDR will be recording the same speed.

 

[itzkatiex0]

All this airplane talk confuses me lol what is a pitot?

 

[Hatfield]

All this airplane talk confuses me lol what is a pitot?

Im just learning too about them but the Pitot Tube is a device mounted on the plane that helps to measure air speed of the aircraft. It is a flow measuring device and it measures air flow.

http://en.wikipedia.org/wiki/Pitot_tube

Good picture of one on right side in link of an A380 Pitot Tube.

The air france disaster was because these tubes iced up and it messed up the instruments of the cockpit thinking it was going faster than it was which caused airplane to stall.
Some are thinking the same thing may have happened again with this recent airplane crash

 

[emirates1957]

All this airplane talk confuses me lol what is a pitot?

They measure air flow and pressure. Next time you board an AC, as you enter look left and you will see a metal tube. These tubes are on both sides of the AC. The will measure the flow of which tells the Pilot how fast they are flying.

 

[Hatfield]

I can remember in high school science class measuring air flow like that using a simplified tube of some sort. The equation in that link is actually pretty complicated. Also in that link, I found this very interesting. I had no idea there were more airplanes beside the Air France one that had those tubes malfunction. Some suspected an insect or a wasp building a nest inside them that malfunctioned them. Oh boy. Those Pitot Tube devices are critical.

From link....
"Operation:
Pitot tubes on aircraft commonly have heating elements called pitot heat to prevent the tube from becoming clogged with ice. The failure of these systems can have catastrophic consequences, as in the case of Austral Líneas Aéreas Flight 2553, Birgenair Flight 301 (investigators suspected that some kind of insect could have created a nest inside the pitot tube: the prime suspect is the black and yellow mud dauber wasp), Northwest Airlines Flight 6231, Aeroperú Flight 603 (blocked static port), and of one X-31.[5] The French air safety authority BEA said that pitot tube icing was a contributing factor in the crash of Air France Flight 447 into the Atlantic Ocean.[6] In 2008 Air Caraïbes reported two incidents of pitot tube icing malfunctions on its A330s.[7] "

http://en.wikipedia.org/wiki/Pitot_tube

 

[itzkatiex0]

Oh okay thanks. 10 am there.. any word on how the waters are?

 

[Hatfield]

Oh okay thanks. 10 am there.. any word on how the waters are?

Unless someone knows the best link that gives up to date information, I struggle to find the latest news. Here is one that is pretty recent but havent seen news for Friday yet.

http://www.ndtv.com/article/world/divers-search-for-bodies-in-fuselage-of-crashed-airasia-jet-648933

 

[itzkatiex0]

Unless someone knows the best link that gives up to date information, I struggle to find the latest news. Here is one that is pretty recent but havent seen news for Friday yet.

http://www.ndtv.com/article/world/divers-search-for-bodies-in-fuselage-of-crashed-airasia-jet-648933

Thanks. Yeah I have trouble too.

 

[sherlockh]

The answer to most of these is in the Air France 447 disaster. :twocents:

AirBus are much more "fly by wire" than other planes.
When something goes wrong the plane thinks it knows better than you do.
This makes it difficult to recover when the pitot tube freezes... because the plane believes the faulty reading.

http://www.telegraph.co.uk/technology/9231855/Air-France-Flight-447-Damn-it-were-going-to-crash.html

The plane did not think it knew better than the pilots. The opposite actually. The plane realized it got faulty readings and turned off the autopilot. Now the pilots had to fly the plane themselves, and they failed unfortunately.

 

[Zuri]

I have taken airplane safety for granted all these years and I am so grateful to those that ensure our safety. I flew on an US Air A320 plane to West Palm Beach out of Philly last year to see my son and go stallion shopping. I am headed there again, but I am driving after all this info about the A320 planes. Are those planes truly safe?