28

To reduce damage in case of a bird strike. The restriction is not only for the 737-100 and -200 models, the 737 NG QRH says: WINDOW HEAT OFF In flight: WINDOWS HEAT switch (affected window) ..... OFF Limit airspeed to 250 knots maximum below 10,000 feet. Pull both WINDSHIELD AIR controls. This vents conditioned air to the inside of ...


25

There are actually two types of de-icing fluid, one is orange and one is green. According to a product safety sheet for one brand: The dye is intended to indicate which parts of the aircraft have been treated and to differentiate between fluids (Type I fluids are orange, Type IV fluids are green). As to why orange and green, presumably they aren't ...


22

Putting this as an answer rather than a comment because of its length. In response to @romkyns comment, perhaps the 787 pilot knew of the heating elements within the wing but was simply telling how ice was normally handled. I really can't imagine him getting through his type rating oral without knowing that. Had you asked me the same question back when I ...


20

Hot bleed air is drawn from the engines and directed through control valves and ducting to the leading edges of the wings and stabilizers. This is what it looks like on a 727. Note that the upper VHF antenna is also anti-iced to prevent ice entering the engine inlets. The 787 uses electric heating elements for the wing instead of bleed air from the engines....


18

That -40 is SAT and in degrees Celsius. The reason that anti-ice is generally no longer needed below that temperature is because at that point, the air is so dry that there isn't enough moisture left to form frost or ice that will stick to the airframe or engine parts. Normally, it's engine anti-ice, rather than wing anti-ice, that is still on when you get ...


17

About your question on why black is not used even though it provides the highest contrast to white: thats not practically true. The problem is, that black and white have the same hue and color saturation (or rather they have no color saturation, and thus the hue is undefined in both cases), so they only differ in brightness/luminance. And a difference in ...


16

Versalog already told the core of the thing. Most prop aircraft which are approved for flights into known icing conditions have such boots to remove the ice from the wings leading edge. Those boots are either inflated manually whenever you need them (by the press of a button of course), at regular intervals or automatically whenever ice is detected. Check ...


15

Using air from the exhaust section either for anti-ice directly, or using a heat exchanger, would create many problems. The air must first be used to burn fuel before reaching a turbine bleed location. Air taken from the compressor section hasn't required any fuel to be burned (other than to compress that air of course). The air will be much, much hotter ...


15

On multiple PPRUNE threads they incorrectly say: The APU bleed is much cooler than the engine bleed system, and would be ineffective for WAI. But the reason is: The APU bleed temperature is unregulated and thus could damage the wing slats if used for anti-ice. Highlight shows regulation of engine bleed temperature.


14

Partially because 787 has no bleed air available for any purpose. Its engines do not draw bleed air traditionally. Any pneumatic system draws air from other pumps. Hence electro-thermal wing anti-ice system is needed since no bleed air is available.


12

Find a picture of any WWII bomber or any modern Cessna Caravan and there should be a black stripe along the leading edge of the wing and tail surfaces. That is termed a boot. (Image source) Inflating it slightly will make the ice break and fall off the wing.


11

There are many things you can do to mitigate the risk of icing, but most involve prevention via avoidance of icing conditions. For example, getting a good weather brief, knowing where the freezing level is, staying away from visible moisture, and finally, recognition and taking evasive action. Pre-flight deicing liquids are not intended to prevent ice ...


11

Generally light GA aircraft have limited anti ice system, usually limited to just pitot heat. Some newer aircraft have been certified for flight into known icing (FIKI) and make use of chemical deicing methods like TKS “weeping wings” or electrically heated systems like the Kelly ThermaWing. I will caution you that, even if your aircraft is FIKI certified, ...


10

Apart from pumping hot air, there are a few ways to achieve wing's leading edge de-icing. Most reliable is through electric heaters just beneath the wing surface. Other are more tricky. One solution is an elastic leading edge, which can be pushed out by, for example, a linear hydraulic motor. If the ice thickness is just right, it will crumble and fall off....


10

Some airplanes don't need the horizontal stabilizer to have anti-ice because it was shown during flight testing that there were no adverse effects from having ice on the tail. This is mainly because the horizontal stabilizer/elevator has been designed so that even with a degradation of lift due to the ice, it still produces a sufficient tail down force to ...


10

I can generally only speak for commercial aviation. The reasoning is probably the same or similar for General Aviation, but seeing as that is such a wide and varied field, with a tremendous number of different aircraft, probe types, etc., someone somewhere could probably find some niche corner-case to dispute the reasoning. My guess would be that, generally ...


10

If an aircraft is not equipped with anti-ice or de-icing systems, than the answer is simple: You don't fly into icing conditions. This is usually listed as an operating limitation in the POH/AFM/FCOM of the respective aircraft. For a Cessna 172, you can e.g. find: KINDS OF OPERATIONS LIMITS The Cessna 172S Nav III airplane is approved for day and ...


9

Traditional anti-ice systems use engine bleed air through the pneumatic system. Engine bleed air is air that is compressed by the engine compressor to high pressure. Due to thermodynamic effects the air also warms to fairly high temperatures. This air is then bled off the engine through valves to supply the aircraft's pneumatic system. The pneumatic air is ...


8

De-ice is a system that removes ice that has formed on a part. Anti-ice is a system that prevents ice from forming on a part. A heated leading edge(bleed air) is an example of an anti-ice system. A inflatable boot on a leading edge is an example of a de-ice system.


8

Fluid Types Wikipedia contains a good summary of the different types of fluid: Types Type I fluids have a low viscosity, and are considered "unthickened". They provide only short term protection because they quickly flow off surfaces after use. They are typically sprayed on hot (130–180°F, 55-80°C) at high pressure to remove snow, ice, and ...


7

Your first reason is the major one: Bleed air is abundant (jet engines generate far more than they "need" for operation), already hot (typically well over 100C), and produced at a relatively high pressure - that's why it's tapped for things like anti-icing systems, cabin air conditioning, and starting other engines. It takes little effort in design to ...


7

It would probably be a single point of failure if one engine wouldn't be enough to deice both wings. For this reason there is a cross bleed selector so that the remaining engine can feed the wing on the opposing side. Here is a link to a computer based training video of the A320 explaining that a single engine bleed is enough for both wings but not for ...


6

What is used to de-ice a commercial aircraft? De-icing fluids are used which are made of ethylene glycol (EG) or propylene glycol (PG) in addition to other ingredients. What is used to de-ice a runway at a large airport? Airports use different types of materials, e.g. potassium acetate. Safegrip ECO2 is a brand which is popular. Runways can also be ...


6

Aircraft stabilizers (both vertical and horizontal) usually have metallic leading edges without paint or anti-erosion paint system. This can be seen in the following figure for Airbus A320 family. Image from Airbus Structure Training Manual For aircraft with composite stabilizers, leading edge erosion is arrested by bonding metal to the leading edge, or ...


6

The reason is that is is new. The B787 is one of the few recent examples of an aircraft where the engineers were allowed to go back to the drawing board and really innovate. It is therefore one of the only examples of a truly new generation of aircraft. Most of the time when an aerospace engineer is asked to work on a new aircraft they are required, for ...


6

Those hot plates, in my experience, are useless. The only reason we had one on our PA34 cargo plane was to make it legal for flight into known icing. As far as I'm concerned, the whole and entire point of those external hot plates is to check a regulatory box to make the plane legal for FIKI if so certified. It never once actually kept ice from ...


5

As the name indicates, anti-icing systems prevent the formation of ice (aircraft surfaces) while the de-icing systems remove the ice after it is formed. Anti-icing systems can be active or passive. In general, most of the active anti-icing systems are thermal, which use the engine bleed air routed through the pipes in wings, engine intakes etc. Source: ...


5

In general, deicing (removal of ice after it had formed) and anti icing (prevention of ice formation) methods used are: Image from GKN Technology: Leading the way toward more efficient aircraft Mechanical which simply pushes the ice off the leading edges. An example is the pneumatic deicing boots, which is the oldest method used where an inflatable rubber ...


5

In the end, for a VFR pilot, if there is any chance of running into rain in winter, it's all about the freezing level. The criteria for use of heat anti-icing on jets for departure is visible moisture (which can be rain, snow or mist/cloud) below +5C OAT. The pressure drop over the wings causes a small temperature reduction that eats into this margin, so ...


Only top voted, non community-wiki answers of a minimum length are eligible