# Tag Info

52

Surface air temperatures aren't really going to be relevant for an airliner. The temperature of the troposphere doesn't vary that much. In fact, the troposphere is warmer at the poles (from Wikipedia Troposphere): At middle latitudes, tropospheric temperatures decrease from an average of 15 °C at sea level to about −55 °C at the tropopause. At the poles, ...

33

They could, if only they were allowed to. From § 121.161 Airplane limitations: Type of route. (a) Except as provided in paragraph (e) of this section, unless approved by the Administrator in accordance with Appendix P of this part and authorized in the certificate holder's operations specifications, no certificate holder may operate a ...

17

Frost can be formed in two ways. On a colder object by water directly desublimating on its surface or on any object when air is saturated with water. Frost can form on a moving airplane, but only the second way. Why would they have anti-ice on pitot tubes, propeller and leading edges otherwise? When the air is not saturated with water, ice will sublimate. ...

16

I'm going to be referring to an old AvWeb article by Mike Busch with my links in this post. As with most of what Mike writes, it's worth a good read. Why is Pre-Heating Important? Pre-heating your engine in the winter is important for a bunch of reasons, but there are two main ones that should get your attention - the first is preventing metal-on-metal ...

16

They are all harder to start in the cold, fuel injected engines included, and need an over-rich mixture for starting. The rich mixture is required because a lean one is harder for a spark to light off if the fuel/air charge is cold. Now, it's still cold outside after the engine warms up, so the air charge is still cold, initially, but on a warm engine it ...

13

Cold weather definitely affects the performance of helicopters (as it does all aircraft), because it affects the density of the air they move through. I will ignore icing so let's assume dry air. The lift equation is: $$L = \frac{1}{2} \rho V^2 S C_L$$ $L$ = Lift $\rho$ = density of the air. $V$ = velocity of the aerofoil (rotor) $S$ = the wing area ...

11

Long story short, as best I can tell everywhere except Kazakhstan uses the ICAO SNOWTAM format. Kazakhstan uses two different Russian formats depending on what airport you're at, which is an interesting approach to say the least. First, the Russian format is described here, it's a decimal value where less than 0.31 is "unreliable" and more than 0.41 is "...

11

"Icing conditions" is a pretty vague term that encompasses a lot of various situations that can cause airframe icing (AOPA pdf report, so it's hard to have one definitive answer. That said, you can expect to accumulate some degree of ice when flying through moisture (clouds, rain, etc) when outside air temperatures (OAT) are near or below 36°F / 2°C. Also as ...

11

Short Answer: Yes, pilots frequently see this phenomenon. No, it does not necessarily present a specific icing hazard. Yes, in some circumstances it can be in indication of an icing hazard. Longer Answer: Speaking for myself, yes, I often see this. I cannot speak for all pilots, but I think many pilots do also see this. The phenomenon depends on several ...

9

Carburetors don't work as well in cold conditions because they themselves tend to cool the air as it flows through the Venturi tube, compounding the issue of cold intake air and cold fuel. From Wikipedia: When the engine is cold, fuel vaporizes less readily and tends to condense on the walls of the intake manifold, starving the cylinders of fuel and ...

8

It's true, carriers typically don't have snow removal and deicing equipment (like trucks, but they do have fluid and spray equipment). They don't have this because they regularly avoid weather that could cause significant icing or snow (carriers move pretty quick and weather is somewhat predictable). But it certainly isn't unheard of that they encounter ...

7

First, I don't think cold weather had anything to do the stopping of rotor. Probably a malfunction. However, Helicopters do face a number of problems during flight in cold conditions Ice accumulation in leading edges- Very few helicopters have leading edge anti-icing systems and are certified for flying in cold conditions (like North Sea). The possibility ...

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

I don't have enough points to make a comment so I'll just leave this one... http://code7700.com/altimeter_temperature_correction.htm All throughout, it's Pilot In Command... Pilot In Command... Pilot In Command... Pilot In Command... 4.1.4 Air traffic control (ATC). If an aircraft is cleared by ATC to an altitude which the pilot-in-command finds ...

6

Flying with the flaps extended is perfectly possible, just inefficient. At that point they were probably just trying to get in the air, not worrying about their fuel efficiency or airborne speed. Otters normally land and take off with flaps somewhat extended. The main problem is that with flaps fully extended, acceleration will be low, so it will be a long, ...

5

They don't. They fly slower. Most aerodynamic effects depend on dynamic pressure. More precisely, lift is proportional to dynamic pressure and drag has parasitic component, which is proportional to dynamic pressure, and induced component, which is inversely proportional. Therefore there is an optimal dynamic pressure at which the aircraft flies most ...

5

Not thermal contraction but condensation of vapor is a problem. Immediately, fuselage pressurization is the far bigger problem that comes with the altitude changes. But if you operate in hot and moist weather, the moisture in all the air carried inside the fuselage will condense when this air cools down at altitude and will collect somewhere. If no proper ...

5

There are a few stages where ice prevention or mitigation is relevant. The FAA publishes a nice handbook on it here if you want more info. Very broadly speaking De-Icing activated when airframe ice is noticed. Anti-Ice is activated when a Pilot believes they may enter icing conditions. Ground based De-Ice is applied when icing conditions prevail in the area. ...

5

FAA Advisory Circular AC No: 23.1521-1B deals with use of IPA for Part 23 aircraft. It states: ASTM D 910, Standard Specification for Aviation Gasolines, allows the use of isopropyl alcohol conforming to the requirements of ASTM D 4171, specifications for Fuel System Icing Inhibitor, as a fuel system icing inhibitor. Accordingly, isopropyl alcohol ...

5

Mike Busch, in an EAA webinar dated 8 September 2011 claims fantastic Engine longevity. He calls a start with the engine below 20°F a significant wear event, recommending preheat below 32°F. Pumping forced air through the cowling for 15 minutes, time enough for a thorough preflight, records check etc, should do the trick. Be careful not to blister the ...

4

OK, I sat on my hands for a while, so now I'll stick my head in the lion's mouth. You should absolutely sump your tanks every time you go flying as part of a routine preflight inspection, whether you've taken on fuel or not, whether the aircraft has been hangared or out on the ramp, and even if it's below freezing. Water isn't the only thing you're looking ...

3

Frost does form if you fly into cloud with the correct temperature and moisture levels as explained elsewhere. It can bring planes down if not protected by anti ice systems or where such systems are not used correctly. Secondly, be wary of taking off with frost on your aircraft. It could have unknown effects on the stall speed and aerodynamic qualities of ...

3

There are multiple ways by which snow can affect the operation in an airport. Snow (and ice) in runway can affect takeoff by absorbing energy and can impact the aircraft after being kicked up by tires. During landing, snow or slush in runway can reduce the deceleration rate by reducing friction coefficient, sometimes causing hydroplaning. The runway length ...

3

It seems as though there was an accident involving a PA-23-180 a while back that lead to this advisory. You can see the full report here (interestingly this was published by the NTSB not the FAA). Require that Piper, Beech, and other airplane manufacturers who have not already done so issue service and operating information regarding the use of fuel ...

3

You can't just adjust the QNH setting to compensate. The temperature adjustment is not linear. The error increases with altitude, so when the altimeter is set for QNH the error at field level is zero. But it increases the higher you go. It's not just everything being X number of feet higher or lower. In your question you say "the aircraft's pressure ...

3

There are 3 critical areas one may wish to address with paint: the formulation of the paint, how it is attached to the substrate, and the properties of the substrate. The substrate may expand, contract, bend or twist with heating, cooling, or stress. The attachment of the paint to the substrate is crucial to durability. Surface preparation includes ...

3

Hot starts are sometimes difficult on fuel injected engines because the engine heat will boil the fuel in the fuel lines, creating a vapor lock. Fuel pumps are designed to pump liquid fuel, not fuel vapor. The same is true for carburetor engines, although usually not as severe. Look at your POH hot start procedure. Usually this involves running the ...

3

There are several considerations for flying polar routes, but no special modifications are necessarily needed. Navigation is different, as Lat/Lon (specifically longitude) converge to become meaningless close to poles, so aircraft traditionally use a grid navigation system. Aircrew should also be aware of the difference between magnetic and true north, as ...

2

I fly a PA-30 Twin Comanche regularly,and,since the POH does not discuss use of isopropyl alcohol or Prist,have contacted Piper repeatedly to seek approval.No response has come from Piper.AOPA and Int’l Comanche Society are equally silent on this topic.I even requested that Air Safety Foundation look into it. I consider this issue of great importance, as the ...

2

Airport workers often struggle to get to work. This is generally OK for the first 12 hours or so but soon, people need to stop working and rest, especially those with safety critical roles which have legally mandated maximum working and rest periods.

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