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67 votes
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Why was my flight cancelled due to bad weather while other flights were not?

In general, flights get cancelled when arriving flights are delayed or themselves cancelled. Your flight needs three critical things to depart on time, or at all: an airplane, flight + cabin crew, ...
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56 votes
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What do pilots landing on aircraft carriers do when the ship is not visible due to weather?

My experience is circa 1990s, but I can offer some perspective on US fixed wing operations. Besides TACAN and ASR for non-precision approaches, there are (were) 3 precision instrument approach options ...
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55 votes
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My windsock is erect, what does this mean?

Windsocks come in various sizes and speeds, but an FAA Standard Wind Sock aligns with the wind at 3 knots, and is fully extended at 15 knots like CGCampbell pointed out. A typical wind sock (at least ...
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44 votes

How common are cancelled landing attempts?

I could see the airport as clearly as one can see an airport in thick fog... If you saw the runway by looking down from your passenger seat as the airplane passed over the airport on the missed ...
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44 votes
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Why is the Cumulonimbus cloud formation so dangerous?

A cumulonimbus cloud (CB) is dangerous because of the processes occurring in them. At a minimum you will have an updraft and a downdraft containing rain. The particular CB you posted in your picture ...
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40 votes
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How do aircraft windshields not crack when flying at supersonic speeds through precipitation?

The Concorde had 2 discrete windshields for different stages of flight. During subsonic flight (mainly take off and landing) the nose was drooped and the inner windshield was exposed. For supersonic ...
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38 votes
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What is the difference between mist and fog?

Quoting from the METAR decoder: BR Mist (Foggy conditions with visibilities greater than 5/8 statute mile) FG Fog (visibility 5/8 statute mile or less) You may ...
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38 votes

How is wind measured at this small U.S. airport?

Ultrasonic anemometers are replacing the traditional cup anemometers in automated weather stations. The sensor measures the time it takes for an ultrasonic pulse to travel between the probes, which ...
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38 votes

How did pilots avoid thunderstorms and related weather before “reliable” airborne weather radar was introduced on airliners?

They looked out the window! If you are talking about a developing thunderstorm, especially during the day, they can be quite easy to see in front of you provided decent visibility. Here is some good ...
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37 votes
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How do pilots foresee turbulence?

There are a few ways that pilots are aware of potentially turbulent areas. Eyesight The most obvious way is just by looking outside and observing the sky. Large billowing clouds, called cumulus ...
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36 votes
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Why would a pilot need to change their heading when flying through a cold front?

In the Northern Hemisphere, wind usually veers to the right when a cold front passes. If you fly through a cold front, the wind also veers to the right. To maintain a constant track, a correction to ...
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35 votes
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Is it difficult for a GA aircraft to escape a thunderstorm?

If you take off with a storm 20 minutes away from the airport, it won't have been "unforecast"; the NWS is much better than that. They can pretty accurately predict what's going to happen regarding ...
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34 votes
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What does a dollar sign mean in a METAR?

A maintenance indicator sign, $, is included when an ASOS/AWSS (Automated Surface Observing System / Automated Weather Sensor System) detects that maintenance is needed on the system. Reference: http:...
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32 votes

How common are cancelled landing attempts?

Q: Was it dangerous? Is it according to standard procedure when approaching an airport in bad weather conditions? If the aircraft did not go below the Decision Height, no, it was not dangerous and it ...
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32 votes
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Why do pilots need the ceiling, time, and dew point in the ATIS?

The ceiling is the lowest altitude where clouds cover more than half of the sky. This is important because climbing above that altitude means you will most likely have to fly through clouds. This ...
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32 votes

When do flights get cancelled due to fog?

Other answers have addressed the case of weather that's too bad for flights to operate, but another situation that can occur is congestion. Take a look at the Average Arrival Rate chart for San ...
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31 votes
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Was ATC overstepping its boundaries when advising a pilot to ignore a cell warning?

The controller didn't overstep his boundaries, and he didn't tell the pilot to ignore a weather warning. Shamrock demanded something that's extreme for the NYC airspace: runway heading for 15 miles. ...
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29 votes

Why do airports have to close in bad weather?

Wind The problem with wind is that it can be from any direction, not necessarily the direction of the runway. When the wind is coming from the side instead of straight ahead, it is called a crosswind....
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29 votes

How do aircraft windshields not crack when flying at supersonic speeds through precipitation?

The first trick to make windshields stronger is used also in aerodynamics: Sweep reduces the effects of speed. Giving the windshield an inclination both back- and sideways will reduce the impact ...
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29 votes

Why did my LGA-ORD flight make an S-shaped turn round the time it was passing a storm?

I find it hard to believe that this was a holding pattern of some sort. Believe it. An hour before landing would be about the point at which the aircraft will start its descent to its destination. ...
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27 votes

What is the difference between mist and fog?

The main difference between the fog and mist is their density and as a consequence, the visibility. From UK Met office: ... they are two distinct terms for a similar phenomenon. Visibility less ...
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26 votes
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Are sun's UV rays more harmful on an airplane at high altitude?

Hmmm, opening the window at 30.000ft, where the air temperature is about -40°C/-40°F, air speed is extreme, you can't survive without oxygen, and you want to put your arm outside??? Well, if you ...
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26 votes
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How is wind measured at this small U.S. airport?

The device used to measure wind speed is called an anemometer. The one that spins with 3 spoon-like arms is just one type. There are some that have a propeller or fan that spins like a windmill. There ...
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  • 8,150
26 votes

Why is the flight duration of the same flight different in different months?

Jet stream is a stream of air flowing around the Earth from West to East at high altitude. With wind speed averaging more than 100+ km/h, it has a tremendous effect on a plane's ground speed. The ...
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  • 39.3k
25 votes

What causes a plane's wing tips to leave a small white vapor trail?

The cause is reduced pressure in the wingtip vortex trailing behind the wing. Reduced pressure causes reduced temperature and if ambient humidity is high enough the result is the condensation you ...
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  • 34.9k
25 votes

Why are pressure levels raised on warm days?

Remember, altimeters sense pressure rather than density. Pressure is essentially a measure of the weight of the atmosphere above a specific point. You can imagine the pressure being measured as the ...
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24 votes
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Do jet contrails impact weather?

Short answer Based on past observations and a study led by Patrick Minnis from NASA, contrails could result in increasing the temperature over the ground by 1°C every 30 years over the US. From a ...
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24 votes

Is it difficult for a GA aircraft to escape a thunderstorm?

Practically speaking this isn't much of an issue, at least under VFR and if you're paying attention. Thunderstorms take some time to form, and as long as you can see them you can avoid them. I'm ...
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23 votes
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Why is mist abbreviated BR on METARs and TAFs?

According to a CFI's lesson plan on the internet, it comes from the French word for mist, brume.
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