# Tag Info

34

As Robbie's answer implies, the answer is wind - Trade Winds govern what happens on or near the surface and were historically important for sailing ships, and today in aviation we deal with the the Winds Aloft at whatever altitude your plane is flying. As an example, consider two hypothetical flights at 30,000 feet with the winds shown below: With these ...

22

Could winds of up to 150 km/h impact the structural loads on the B777-200LR? Not at all. The dynamic pressures on the plane depend on the plane's velocity with respect to the air, not the ground speed. Flying in 150 km/h tailwind is the same as flying with no wind, the plane's indicated and true airspeeds won't be affected. True airspeed is the plane's ...

10

Most flights across the Atlantic don't fly direct great circle routes; they use the North Atlantic Track system, which is an array of "lanes" you might say, usually 60Nm apart, like one of those slot car racing places with 6 or 8 lanes of cars. Just about everybody that can make the trip non-stop will be in the tracks at various altitudes. Off each coast ...

9

Before even taking off, a pilot is required to get a weather briefing, including winds. Wind speeds are usually predictable and well known. If a pilot was flying against strong headwinds, with no good landing alternate, he screwed up his flight planning before he even started the engine. A headwind doesn't even have to be strong enough for negative GS, ...

9

can an autopilot be programmed to follow a route dictated by a winds aloft forecast? Yes, but the question is how it is done, and these days it's better to think of it as not just the autopilot, but a Flight Management System (FMS). In the case of the North Atlantic Track system explained by John K, the waypoints that define the route an airplane is to ...

6

With the set of parameters available to you, you cannot do this. If you have the actual track instead of the desired track, you will be able to calculate the wind. The simplest way to do this is using vector math. There are three vectors to consider: ground speed vector $\vec{V_{gs}}$ air speed vector $\vec{V_{as}}$ wind speed vector $\vec{V_{ws}}$...

5

No, there's no considerations on structural load because the airplane is moving in relation to the air mass. Think of the jet stream as a river, as air is just another fluid. A boat heading downstream on a fast moving river will move faster in relation to the land, but in relation to the water it's moving the same speed as if it were on a lake with no ...

4

ymb1's and GdD's answers are very good, I'd like to expand them a bit further. The loads on the airplane structure are caused by forces between air and the plane. If the stream can be described as laminar flow, there is no difference between flying in headwind, tailwind or calm air. Except for ground speed, obviously. When onboard and near the wing, you ...

4

The jet stream moves from West to East. At the altitude an airliner flies the speed of the tail wind or head wind will have a significant impact on actual ground speed. This was first observed when B-29 bombing raids on Japan during WW2. Before that there was no notion of a 'jet stream'.

4

Yes, they are NOTAM'ed. In the FAA case, the FAA wants to know first when you intend to launch, where from (distance and direction from a town on a map), how high you expect to go and what direction you expect it to travel in. 24 hours before launch, you have to call your local Flight Service Station (FSS) and file a Notice to Airmen (NOTAM) giving the ...

3

An alternative to the Boeing data (if it exists, you might need to call one of their sales reps to find it) is publicly available meteorological data. One such project is the NCEP/NCAR Reanalysis Project. There are a few others, as well as archived data. None of these is exactly the Boeing dataset, but I'd bet that the Boeing dataset is based at least in ...

3

Is there a maximum or safe winds aloft value / crosswind for say, a 737 to fly? Crosswind limits are in place for landing not flying. Cross wind limits have to do with how effective the control surfaces are which allows you to fly the plane in such a manner where the fuselage is aligned with the ground track. At altitude winds simply either add to your ...

2

I like to show people videos of planes flying backwards. These videos show that wind does not have an effect on how well the aircraft stays in the air - no matter how strong it is, it only effects the path taken over the ground. A steady wind makes zero difference to the aerodynamics, whether it is a piper cub or a 747. The aircraft doesn't know what the ...

2

This question is actually applicable to a power off emergency gliding situation, where your best option may be behind you. The way the question is worded (and one of the reasons light GA air craft are generally designed with one wing and a bit more speed than old time Jennys) is that progress upwind will drain your energy source (be it altitude or fuel) ...

1

If you are flying into a headwind, that means that there is an area of High pressure to your right. Frequently, as you leave move further away from the low pressure area, the winds will diminish. This isn't always the case, but it is the PICs responsibility to check weather conditions along the route and the routes to any alternate destinations.

1

Short answer: As you have indicated in the question description, the answer is winds. Better known as Jet Streams. Long answer: https://alliknowaviation.home.blog/2019/03/29/why-do-planes-travel-faster-west-to-east/

1

The wind data that Jeppesen/Boeing uses is proprietary, they have their own meteorologists. Similar data is available from NOAA. They have a data server that can provide wind information.

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