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Very sad morning. I have a question. The flight was cleared down to 2300 ft. If ice was accumulating and it sounds like it was, how much of a factor could this possibly play into the flight controls? I do understand what ice does to the wing, but i'm curious as to what affect ice has on the actual mechanics of the flight controls. Thanks in advance.
Very sad morning. I have a question. The flight was cleared down to 2300 ft. If ice was accumulating and it sounds like it was, how much of a factor could this possibly play into the flight controls? I do understand what ice does to the wing, but i'm curious as to what affect ice has on the actual mechanics of the flight controls. Thanks in advance.
In most cases ice will only form on the leading edge of the wing (or any other surface like the picture below.
In some extreme cases you can have what is called runback icing where the drop of supercooled water (water that is below freezing, but not frozen yet) splatters on the wing and spreads out and runs back past the icing protection before it freezes. I can't picture there being enough to run all the way back to any of the flight controls.
The danger of icing isn't that it will ice up your flight controls but rather that it will disrupt the smooth airflow over the wing which basically turns you into a test pilot because now your wing is shaped completely different, which severely changes/reduces your ability to make lift.
How does the pilot know that ice is forming other then flying in "known icing conditions" and how offten are the de-icing boots activated?
Is it a totaly manual process or do you enable them and then they operate at preset intervals? Can they be over-used?
Does the "feel" of the aircraft change or is more power required to maintain altitude?
Thanks Emu...Interesting little tid bit I found here concerning ice in this particular type of aircreft. This incident happened on take off. Emu another quick question. When flying in known icing conditions how often do you fly the plane in autopilot? Thanks again.
We are still making a few big leaps in assuming that it was icing (although it is certainly a good possibility). Aircraft are reporting icing, but none are reporting it to a level that the aircraft can't deal with.
Certainly not nice weather conditions to be operating in though... Ice is definately something to be respected.
AvFasc.... its a bit early to claim irresponsibility when the conditions appear on the surface to be acceptable to make an approach.
Qudos to the ATC'er who did an excellent job given the circumstances.
How does the pilot know that ice is forming other then flying in "known icing conditions" and how offten are the de-icing boots activated?
Is it a totaly manual process or do you enable them and then they operate at preset intervals? Can they be over-used?
Does the "feel" of the aircraft change or is more power required to maintain altitude?
I can't speak for the de-icing boots as I have never flown a plane with them but there are a few ways to discover ice on the airplane. I can't speak for the Q400 but as they are made by the same manufacturer as the one I fly I would imagine (perhaps falsely) they are similar.
The first way is by knowing when you are in conditions suitable for icing. For my plane it is in visible moisture (clouds, snow, rain, fog, etc) below 10 degrees C. You won't always get icing in a cloud below that temperature though, but its possible. It all depends on the makeup of the cloud (ice or water).
The second is visually. Ice will form on the smaller parts of the airframe before the larger ones. A larger surface (a wing for example) pushes more air out of the way in front of it as it moves through the air. This will cause the water molecules to go above or below the wing instead of impacting it. A small surfaces affects less air around it so the water is more likely to runs smack into it. One of the first places I look for ice is on my windshield wipers. They're small and they're right out in front of me. That's also a good way to find out what kind of ice that you are getting (rime, clear, mixed).
The last way, which I'm not sure if the Dash has, is an ice detector. A few feet below the cockpit window there is a small probe that is shaped like the cross section of a wing. Sticking out of this is a small pin which is designed to vibrate at a certain frequency when air flows around it. If ice forms on the probe, the frequency will decrease and the computer will notice and alert us on the EICAS. This probe is heated (I forget exactly how frequently) to melt off the ice and allow it to re accumulate.
We are still making a few big leaps in assuming that it was icing (although it is certainly a good possibility). Aircraft are reporting icing, but none are reporting it to a level that the aircraft can't deal with.
Certainly not nice weather conditions to be operating in though... Ice is definately something to be respected.
AvFasc.... its a bit early to claim irresponsibility when the conditions appear on the surface to be acceptable to make an approach.
Qudos to the ATC'er who did an excellent job given the circumstances.
Yeah...in providing explanations to peoples questions I am not suggesting that I think it was ice that brought this plane down. I absolutely hate when people jump to conclusions. The crew is dead, they deserve better than to be second guessed. Allow professional investigators to figure out the cause instead of jumping to conclusions. Have some respect.
I do however like answering peoples questions to help educate and hopefully stop the spread of false information. The media doesn't know a thing about aviation.
Thanks Emu...Interesting little tid bit I found here concerning ice in this particular type of aircreft. This incident happened on take off. Emu another quick question. When flying in known icing conditions how often do you fly the plane in autopilot? Thanks again. http://www.aviation.ca/content/view/3231/118/
You do bring up a good point that I forgot to mention. As ice picks up on the wings and the reduction in lift begins the airplane will have to fly at a higher angle of attack to create the same amount of lift. The autopilot doesn't have a brain so if it notices the airplane isn't maintaining the altitude or rate of climb/descent that you are asking of it, it will begin to increase the angle of attack as much as it needs to, even up to a stall.
Personally I like flying airplanes so I like to handfly as much as possible during approaches. I'm still fairly new to this so I haven't flown in icing bad enough that I thought it a good idea to disconnect the autopilot. But I do keep an eye on the trim to make sure it looks fairly normal while in ice.
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