I was on a flight that listed the tail wind as being 160 mph at one point. Is that accurate or common? If so, it's quite surprising that winds at cruising altitude move that fast.

Not sure if it affected things, but it was rough flight the entire way.

Coming back down in Detroit through heavy clouds was particularly rough.

Were you flying west to east?

https://en.wikipedia.org/wiki/Jet_stream

Florida to Michigan

I was on a flight not to long ago where the pilot, when announcing flight times and all that, mentioned a huge tailwind — I wanna say 150+ MPH if I recall correctly.

I didn’t know that was normal “or uncommon”. Pretty cool.

That makes no sense you should be fighting the jet stream going FL to MI so you should have head winds not tail winds.

quote:

Originally posted by Skins2881:
That makes no sense you should be fighting the jet stream going FL to MI so you should have head winds not tail winds.

Depends on where the jet stream is dipping and rising and the travel corridor used. A mid country dip might have an upswing that gives a tail wind, at least at a latitude higher than over Florida.

Yes, jet stream has winds that fast, If a plane is flying with the jet Stream it will fly faster as the wind is on its tail. If it is flying into the jet stream it will go slower. I picture the Jet Stream as being a river of air that moves extremly fast and moves like a snake. Rarely will a plane fly against it because they will use to much fuel

quote:

Originally posted by chansen92:
Yes, jet stream has winds that fast, If a plane is flying with the jet Stream it will fly faster as the wind is on its tail. If it is flying into the jet stream it will go slower. I picture the Jet Stream as being a river of air that moves extremely fast and moves like a snake. Rarely will a plane fly against it because they will use to much fuel

That is not technically correct. If it is flying into the wind, it will increase throttles to maintain desired speed. If it is flying with the wind, they throttle back the engines.

There is no 'faster' to it. Commercial airlines are going to maintain a specific speed threshold.

^^^

It is technically and literally correct.

Some transoceanic flights have flown near 800 MPH ground speed with 200 MPH jet stream "assist". That is rare, and about 100-120 MPH is more prevalent.

As far as "pushing up the throttles" with the jet-stream on the nose, you cannot exceed the rated limit for (various factors) at altitude and most airliners fly near that at cruising altitude. It is a very narrow envelope, so if encountering that same 200 MPH jet-stream, they will be flying 200 mph ground speed.

The aircraft only "knows" how fast the airspeed is in relation to the aircraft. It does not care how fast that mass of air it is in, is moving above the surface of the earth.

The throttle setting for .8 Mach (indicated airspeed) at altitude in the jet-stream will be the same for two identical aircraft in the same jet-stream, going opposite directions and the indicated ground speed would be +/- the jet-stream relative to them.

This was yesterday over the Pacific, approaching the international date line.

141 knots on the tail, which is 162 mph of tailwind. Fairly common in the Pacific.

Amd what sigmonkey said is correct. .82 Mach is .82 Mach for the airplane - it does not care if it has 100 knots on the nose or on the tail.

quote:

Originally posted by Skins2881:
That makes no sense you should be fighting the jet stream going FL to MI so you should have head winds not tail winds.

No, not always true. Jet stream is not a straight line. It is affected by many things.

In the northern hemisphere, winds circulate clockwise around a high pressure area, counter clockwise around a low.

For circulation in southern hemisphere, check with Bart Simpson.

quote:

Originally posted by V-Tail:

quote:

Originally posted by Skins2881:
That makes no sense you should be fighting the jet stream going FL to MI so you should have head winds not tail winds.

No, not always true. Jet stream is not a straight line. It is affected by many things.

In the northern hemisphere, winds circulate clockwise around a high pressure area, counter clockwise around a low.

For circulation in southern hemisphere, check with Bart Simpson.

Every map I have seen the jet stream looks like this one or has the peaks and troughs flattened out. Some times more northerly sometimes more southerly, but always heading from west to east. Never have I seen it blow from east to west regardless of it's latitude. Sometimes nearly north to south or south to north, but overall easterly, never westerly.



I don't know the routes planes take but I assume it's generaly a straight line from point to point and it wouldn't say fly to Texas that take a right and heat to MI, or fly from FL to NY then take a left to get to MI. If that's the case I guess I could see a tail wind.

I don't think Hi and Low pressure systems create 150mph winds around the systems, but if that is the case than I guess you could have a storm system blow just about any direction at any given point.

High winds aloft are very very common. Although the CW is they blow from West to East, that can vary greatly with weather patterns, season, etc.

In the Navy, it was very common to go West coast to East coast with one refueling stop, but the reverse took two stops.

You can vary your altitude just a little bit in order to find better winds, either in magnitude, direction or both. On long distances flights is can make a huge impact on arrival time, refueling, and range.

https://aviationweather.gov/windtemp

Another component to this is the rather sophisticated flight planning programs that take this into account planning a flight. They will look for the best tailwind or the lowest headwind, combined with other considerations.

Of course different type and weight planes will vary a bit with ‘optimum altitude’, ‘overflight fees’ are also included. Weather systems and certain levels of ‘known’ adverse ride conditions are considered.

Oftentimes the shortest mileage route may not be the best time. The fastest ground speed I remember seeing was 711 knots off the coast of Japan with a ‘winter’ jet stream.

quote:

Originally posted by Jager:

quote:

Originally posted by chansen92:
Yes, jet stream has winds that fast, If a plane is flying with the jet Stream it will fly faster as the wind is on its tail. If it is flying into the jet stream it will go slower. I picture the Jet Stream as being a river of air that moves extremely fast and moves like a snake. Rarely will a plane fly against it because they will use to much fuel

That is not technically correct. If it is flying into the wind, it will increase throttles to maintain desired speed. If it is flying with the wind, they throttle back the engines.

There is no 'faster' to it. Commercial airlines are going to maintain a specific speed threshold.

Jager, to be technically correct, airplanes fly through air and maintain airspeed. They will often adjust their route and/or altitude to find favorable winds that give them better ground speed. They don’t just throttle up to increase speed.

The route down went through KY and Knoxville, TN (literally right over my old apartment). The route back to Michigan swung farther east over the Carolinas, Virginia and part of West Virginia.

My personal record was 176 knots in the face last winter. Never seen winds that high before. The jet stream over the US tends to be stronger in the winter months.

Edited to add to what the poster above mentioned. We fly indicated airspeed down low and MACH numbers at higher altitudes. Groundspeed is what you get when you subtract/add the indicated airspeed to the headwind/tailwind component.

A general rule of thumb for efficiency is to fly slightly higher indicated airspeed or MACH number into a headwind. Conversely you could slow down a little with a tailwind to burn a little less fuel with a similar time enroute if you were worried about fuel conservation (and who isn't these days?).

quote:

Originally posted by Jager:


That is not technically correct. If it is flying into the wind, it will increase throttles to maintain desired speed. If it is flying with the wind, they throttle back the engines.

There is no 'faster' to it. Commercial airlines are going to maintain a specific speed threshold.

quote:

Jager, to be technically correct, airplanes fly through air and maintain airspeed. They will often adjust their route and/or altitude to find favorable winds that give them better ground speed. They don’t just throttle up to increase speed.

Yes, they will.

Doing 500 KIAS, encounter 150 kt headwind, speed will reduce accordingly to 350 kts ground speed.

Pilot WILL increase throttles to overcome the reduction in speed - of course, observing aircraft design limitations - and more than likely will adjust altitude to avoid the headwind. But no pilot is going to crawl along at 350 kts ground speed unless they are forced to.

What you said - was exactly what I said...

quote:

Originally posted by Jager:

quote:

Originally posted by Jager:


That is not technically correct. If it is flying into the wind, it will increase throttles to maintain desired speed. If it is flying with the wind, they throttle back the engines.

There is no 'faster' to it. Commercial airlines are going to maintain a specific speed threshold.

quote:

Jager, to be technically correct, airplanes fly through air and maintain airspeed. They will often adjust their route and/or altitude to find favorable winds that give them better ground speed. They don’t just throttle up to increase speed.

Yes, they will.

Doing 500 KIAS, encounter 150 kt headwind, speed will reduce accordingly to 350 kts ground speed.

Pilot WILL increase throttles to overcome the reduction in speed - of course, observing aircraft design limitations - and more than likely will adjust altitude to avoid the headwind. But no pilot is going to crawl along at 350 kts ground speed unless they are forced to.

What you said - was exactly what I said...

A plane at 30000 feet, flying with a 500 knot ground speed into a 150 knot headwind, is breaking the sound barrier. With very few exceptions, civilian aircraft do not break the sound barrier on purpose because the sound barrier tends to break them back.

Large passenger aircraft fly close enough to the speed of sound that they simply CAN'T speed up to compensate for a significant headwind.

quote:

Originally posted by Jager:

quote:

Originally posted by Jager:


That is not technically correct. If it is flying into the wind, it will increase throttles to maintain desired speed. If it is flying with the wind, they throttle back the engines.

There is no 'faster' to it. Commercial airlines are going to maintain a specific speed threshold.

quote:

Jager, to be technically correct, airplanes fly through air and maintain airspeed. They will often adjust their route and/or altitude to find favorable winds that give them better ground speed. They don’t just throttle up to increase speed.

Yes, they will.

Doing 500 KIAS, encounter 150 kt headwind, speed will reduce accordingly to 350 kts ground speed.

Pilot WILL increase throttles to overcome the reduction in speed - of course, observing aircraft design limitations - and more than likely will adjust altitude to avoid the headwind. But no pilot is going to crawl along at 350 kts ground speed unless they are forced to.

What you said - was exactly what I said...

You're both right, and you're both wrong. Since we're only talking about commercial airlines, the altitude and airspeed windows we operate in at cruise are relatively small. Cruise speed is a result of many factors taken in by the flight planning software dispatchers use to plan the flight. It is always going to be a balance between flight time and fuel burn and dispatchers can bias for one or the other depending on conditions.

All things being equal, when flying into a headwind they usually bias toward flight time to meet the schedule which results in a slightly faster cruise speed but greater fuel burn. Likewise, when flying with a strong tailwind they can slow us down to minimize fuel burn while keeping the schedule because of the higher ground speed. Keep in mind we're talking a spread of 20 to 30 knots here for a 737 or similar airplane, not a huge margin when you're cruising around 450 knots.

And there are plenty of times I've puttered along at 350 knots or less in a 737 into a headwind. Why, because like I said our altitude options are relatively limited. Commercial airliners typically max out at 41,000 feet or less depending on weight, so climbing above the jetstream is basically never an option. Flying below it may get you out of the wind, but jets burn a lot more fuel at low altitude so you could actually end up using more fuel than flying high into the wind. Same with trying to fly around it, the increased distance could take longer and/or burn more gas than a shorter route into it.

You also have to take into account areas of turbulence which are common when there's a strong shear between the jet and the air around it. Again this is all stuff dispatchers look at when planning a flight, and of course there's ATC and airspace issues as well.