# Aircraft turns from headwind to tailwind - loss of IAS? **URL:** \ **Category:** Factual Questions\ **Created:** [December 23, 2009, 10:59pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386 "2009-12-23T22:59:27Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [December 31, 2009, 3:56pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/61 "2009-12-31T15:56:36Z")
> [@Xema](#): > > No - there is nothing special about the earth-based frame of reference. Except for the minor detail about gravity. [quoyrFor a more extreme example, consider flying at a steady speed and altitude in an airliner. Is there anything fundamentally different about walking around, or tossing a ball at 550 knots as compared to doing the same thing while stationary at the gate? Galileo said: absolutely not. [/QUOTE] In steady state, no. But we’re discussing \*transient \*events, in which acceleration is \*not \*zero. F = m a. Have you been reading this thread at all? **1920** , an inertial FOR would be one centered on the aircraft, not the earth. **ZB** seems to think it’s centered on the treadmill. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [December 31, 2009, 4:35pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/62 "2009-12-31T16:35:07Z")
> [@ElvisL1ves](#): > > **1920** , an inertial FOR would be one centered on the aircraft, not the earth. **ZB** seems to think it’s centered on the treadmill. If you were driving around on a treadmill, that would be perfectly correct. Dont use a poor analogy created by yourself to “show” how ZB is wrong. If you are **flying** around in a uniformly moving airmass, thats the reference you use. Either you dont really understand this stuff or your terminology and explanations need some work. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [December 31, 2009, 6:52pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/63 "2009-12-31T18:52:48Z")
If you need gravity explained to you, you’ll have to find somebody else to do it, sorry. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [December 31, 2009, 6:58pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/64 "2009-12-31T18:58:57Z")
**ElvisL1ves** , you seem to be the one who needs things explained. Answer this: do you think the plane’s inertia is _caused by_ Earth’s gravity? Do you think the plane’s inertia is _affected by_ Earth’s gravity? ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [December 31, 2009, 11:33pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/65 "2009-12-31T23:33:32Z")
> [@ElvisL1ves](#): > > **1920** , an inertial FOR would be one centered on the aircraft, not the earth. **ZB** seems to think it’s centered on the treadmill. Did you read my link? It explains inertial frame of references and you are flat out wrong. An inertial FOR is one that is NOT accelerating. The aircraft is NOT an inertial frame of reference in a turn, but the the airmass is, the airmass is in a steady state, it is NOT accelerating and doesn’t require imaginary forces to make the physics work. So the airmass is the frame of reference, the aircraft is moving within the airmass, it doesn’t matter one bit what the airmass is doing relative to the ground. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 31, 2009, 11:37pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/66 "2009-12-31T23:37:15Z")
Here’s an idea: Someone go up and make a standard-rate turn on a windy day. Have someone video the panel. See if the airspeed changes. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [December 31, 2009, 11:42pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/67 "2009-12-31T23:42:44Z")
> [@ElvisL1ves](#): > > > [@](#): > > > > For a more extreme example, consider flying at a steady speed and altitude in an airliner. Is there anything fundamentally different about walking around, or tossing a ball at 550 knots as compared to doing the same thing while stationary at the gate? Galileo said: absolutely not. > > In steady state, no. But we’re discussing \*transient \*events, in which acceleration is \*not \*zero. F = m a. Have you been reading this thread at all? You don’t seem to get the analogy. Lets compare it with the movement of an aeropolane within a steady airmass. In the example of walking around or throwing a ball in an airliner, the _ball_ and _person_ walking around are both accelerating, as is the aeroplane in a turn, meanwhile the airliner is in a steady state, as is the airmass. Get it? The airmass is steady state and the aeroplane is moving within it, just like the airliner is steady state and the ball is moving and accelerating within it. The airmass is the inertial frame of reference within which the movement of the aeroplane is measured. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 1, 2010, 10:42pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/68 "2010-01-01T22:42:43Z")
> [@ElvisL1ves](#): > > In steady state, no. But we’re discussing \*transient \*events, in which acceleration is \*not \*zero. Galileo was also considering transient effects - they were happening within his (imagined) inertial frame of reference on board a 17th century ship. **1920s Style “Death Ray”** has it right: > [@](#): > > The aircraft is NOT an inertial frame of reference in a turn, but the the airmass is… ---
**Author:** ![agustincabreze](https://avatars.discourse-cdn.com/v4/letter/a/ce73a5/32.png) [@agustincabreze](https://boards.straightdope.com/u/agustincabreze)\ **Post date:** [April 12, 2016, 12:25am UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/69 "2016-04-12T00:25:03Z")
> [@Richard\_Pearse](#): > > No this is wrong. The aircraft moves within the airmass and the movement of the airmass over the ground has absolutely NO effect on the air speed of the aircraft. If it did imagine what would happen to aircraft flying at high altitudes in winds of 100 knots or more, when they turned downwind they’d be falling out of the sky, they’d certainly have wild fluctuations in IAS, but this does not happen. > > I don’t have time to read the whole 30 pages of the report but the section quoted is either poorly worded or the investigator doesn’t know his stuff. > > There _are_ some dangers with manoeuvering at low level in windy conditions and some of them may be mistaken for a loss of IAS when turning downwind. > > When turning from into wind to downwind there is an increase in ground speed and when at low level the pilot may _perceive_ the increase in ground speed as a lowering of the nose and instinctively raise the nose. This will cause a loss of IAS, but it is due to the nose being raised not the wind. > > When flying through airmasses moving at different speeds you may get a loss in IAS. So if you were to climb or descend into an _increasing_ tailwind or _decreasing_ headwind you would experience a decrease in IAS, but this is due to a _change_ in the airmass you are flying through. This type of thing is common because the wind is slower close to the ground due to friction and so when climbing and descending at low levels it is common to experience changing wind conditions. > > You may experience a similar thing if you were to turn in a valley. The turn may take you toward rising terrain so as you got closer to the ground the wind would likely be slower and you may experience changes in IAS due to the change in the airmass you’re flying through. > > Turbulence can cause fluctuations in airspeed. > > But note that in all these cases, the change in IAS is due to a _change_ in the air you are flying through. > > There is one other thing that decreases IAS during a turn. When in a turn the wing is banked and therefore the lift vector is at an angle. As the _vertical_ component of the lift vector must equal the weight of the aircraft to maintain level flight, the lift vector has to be increased. In short, when turning you need more lift to maintain altitude and one of the side effects of lift is drag. Extra drag causes a decrease in IAS if it is not compensated for with an increase in thrust. This will happen in any level turn and is unrelated to wind. > > **Mach Tuck** what you are noticing from your students is probably due to the change in wind as they descend. > > **hibernicus** your understanding of IAS in a turn is correct. Your explanation seems fantastic to me. I would like to write down some things that I cant get clearly, and I would be glad if you can correct my or give me your points of view. I think that the IAS can be affected by the wind and its changes in direction and speed, but it depends on how suddenly this change happens. For example, if you take off with a headwind of 20 kts, and your aircraft flies at 70kts IAS, if you make a 180° slow change in your direction , getting a 20kts tailwind now, you won’t even notice the movement of the needle, cause that wind will get time enough to overcome the aircraft incercia. But , hypothetically, if that change in direction can be done from one second to another, in a sudden way, now you will do see a decrease in you IAS, cause in that sudden change the 20kts tailwind will try to push either your aircraft and the air that is in front of your aircraft pitot tube, but as that air is lighter than your plane, it is going to be “pushed” first. So, at that time, you will get your IAS decreased, until that tailwind (after some seconds or minutes) beats you aircraft inercia, where the IAS will recover its normal indication of 70kts. This is my point of view, after reading about this topic for several days. Please, im open to every single opinion, either if you agree or not. Thanks for letting me share this words here. Forgive my English, im from Argentina. Best regards, Agustin. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 12, 2016, 12:58am UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/70 "2016-04-12T00:58:40Z")
> [@agustincabreze](#): > > Your explanation seems fantastic to me. I would like to write down some things that I cant get clearly, and I would be glad if you can correct my or give me your points of view. > > \*\*I think that the IAS can be affected by the wind and its changes in direction and speed, but it depends on how suddenly this change happens. \*\*For example, if you take off with a headwind of 20 kts, and your aircraft flies at 70kts IAS, if you make a 180° slow change in your direction , getting a 20kts tailwind now, you won’t even notice the movement of the needle, cause that wind will get time enough to overcome the aircraft incercia. But , hypothetically, if that change in direction can be done from one second to another, in a sudden way, now you will do see a decrease in you IAS, cause in that sudden change the 20kts tailwind will try to push either your aircraft and the air that is in front of your aircraft pitot tube, but as that air is lighter than your plane, it is going to be “pushed” first. So, at that time, you will get your IAS decreased, until that tailwind (after some seconds or minutes) beats you aircraft inercia, where the IAS will recover its normal indication of 70kts. > > This is my point of view, after reading about this topic for several days. Please, im open to every single opinion, either if you agree or not. > Thanks for letting me share this words here. > Forgive my English, im from Argentina. > Best regards, > > Agustin. Bolding mine. Welcome. Your thoughts are basically correct. If the wind shift is very sudden, aircraft inertia rules and the result is IAS changes instantly in response to the wind shift. At which point the equilibrium of thrust & drag is unbalanced and the unbalance causes the aircraft speed (both inertial & IAS) to change in response. For example, a sharp wind shift may result in a sudden loss of 10 knots of IAS. At which point your thrust is higher than needed for your newly reduced drag. So over the next 5, 10, or 20 seconds the excess engine thrust will increase the speed back up to equilibrium. And meanwhile you may be descending a bit as well from loss of lift due to loss of IAS. Conversely, if the wind shift is slow enough the effect of the wind shift is lost in the overall aircraft vs. airmass interaction. From the aircraft’s point of view a downwind turn is simply a windshift that takes several to 30 seconds to play out. The effect of wind shifts & downwind turns is more obvious on slow moving aircraft with low power. Which was all of them in the pioneering days of aviation. Nowadays it’s pretty much ultralights and powered parachutes which need to be concerned about downwind turns. Truly abrupt wind shifts are called “windshear” and can be severe enough to drop jets from the sky. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [April 12, 2016, 1:53am UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/71 "2016-04-12T01:53:53Z")
> [@LSLGuy](#): > > From the aircraft’s point of view a downwind turn is simply a windshift that takes several to 30 seconds to play out. For once I disagree with you. From the aircraft’s point of view a downwind turn is not a windshift at all. Two distinct scenarios: 1. The airmass is completely stable, i.e., there is no turbulence or any change anywhere, all of the air is still relative to the air around it. 2. The airmass is not stable, there are changes in air movement depending on how high you are or where you are laterally. In scenario 1 the aircraft doesn’t see any wind shift because there isn’t any. Any turns will not result in any change of airspeed other than for aerodynamic reasons such as additional g-loading during the turn. This is the situation with a turn in a steady wind. Note that I haven’t mentioned anywhere what the air is doing in relation to the ground, this is because it is irrelevant. It could be a 200 knot wind or no wind at all. As far as the aircraft is concerned it moves within the air mass and is entirely unaffected by the movement of the air over the ground. In scenario 2 yes there are windshifts and as the aircraft moves from a bit of air moving with a certain velocity to another bit of air moving at a different velocity there will be changes in airspeed. This is the situation with turbulence, wind gradients, windshear etc. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 12, 2016, 2:06am UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/72 "2016-04-12T02:06:58Z")
If the wind is steady, and the pilot is not spooked or tricked in some way by looking at the ground, then as the airplane turns it will lose some amount of airspeed. The amount of airspeed lost during a turn depends only on how abrupt the turn is. It does not depend on the speed of the wind, or whether the plane is flying upwind, downwind, or crosswind. If the airplane reverses direction within ten seconds, say, it will lose the same amount of airspeed if it’s flying in still air, or switching from upwind to downwind, or switching from downwind to upwind. ---
**Author:** ![doubleminus](https://avatars.discourse-cdn.com/v4/letter/d/5daacb/32.png) [@doubleminus](https://boards.straightdope.com/u/doubleminus)\ **Post date:** [April 12, 2016, 2:17am UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/73 "2016-04-12T02:17:30Z")
It might be easier to visualize this if one considers the air to be always fixed and the Earth is moving below. Obviously it does not matter how fast and into which direction the Earth moves below, for an airplane (or for that matter a balloon) to sense it. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [April 12, 2016, 2:32am UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/74 "2016-04-12T02:32:46Z")
> [@agustincabreze](#): > > Your explanation seems fantastic to me. I would like to write down some things that I cant get clearly, and I would be glad if you can correct my or give me your points of view. > > I think that the IAS can be affected by the wind and its changes in direction and speed, but it depends on how suddenly this change happens. For example, if you take off with a headwind of 20 kts, and your aircraft flies at 70kts IAS, if you make a 180° slow change in your direction , getting a 20kts tailwind now, you won’t even notice the movement of the needle, cause that wind will get time enough to overcome the aircraft incercia. But , hypothetically, if that change in direction can be done from one second to another, in a sudden way, now you will do see a decrease in you IAS, cause in that sudden change the 20kts tailwind will try to push either your aircraft and the air that is in front of your aircraft pitot tube, but as that air is lighter than your plane, it is going to be “pushed” first. So, at that time, you will get your IAS decreased, until that tailwind (after some seconds or minutes) beats you aircraft inercia, where the IAS will recover its normal indication of 70kts. I think the problems here come from mixing reference frames. You can either measure the aircraft’s motion relative to the ground or relative to the air it is moving through. If you try to use a mixture it doesn’t work and you get the wrong answer. When you talk about wind you are using the ground as a reference and should be using **ground speed** when referring to the aircraft, but when you are talking about airspeed you are using the air as a reference. Using your example I will first look at it with reference to the air and then separately with reference to the ground: 1. An aircraft is moving at 70 knots IAS through the air. It turns through 180º as abruptly as it can and is now travelling in the opposite direction at 70 knots IAS. It seems like there should be more here, but that’s it, that is the scenario in its entirety, any attempt to introduce wind speed is mixing the ground reference frame with the air reference. 2. An aircraft is moving at 70 knots IAS through air which is moving at 20 knots over the ground in the opposite direction as the aircraft. The aircraft has a **ground speed** of 50 knots. It turns as abruptly as it can and is now moving at 70 knots IAS with the 20 knot wind. The ground speed is now 90 knots. The aircraft has gone from 50 knots ground speed to 90 knots ground speed. Where does the energy come from to accelerate it from 50 to 90 knots GS and stop it from stalling? Answer, the wind itself. When viewed from the reference of the ground, the movement of the aircraft is the sum of the aircraft movement through the air and the air movement over the ground. So in example 1 there is no change in airspeed because the airspeed is measured only with reference to the air. What the air does over the ground is not relevant. In example 2 there is a change in **ground speed** and the energy required to achieve that change comes from the wind. The wind is relevant in this case because it is by combing the wind and aircraft vectors that gives resulting movement over the ground. Both examples are equivalent but viewed relative to different frames of reference. Remember, as soon as you start trying to relate the wind speed (ground reference) to changes in **air** speed (air reference) you are mixing reference frames and the answers become invalid. This all has the caveat that the airmass is steady, i.e, no movement of one bit of air relative to another bit. And that we are ignoring aerodynamic effects such as mentioned by \*\* Chronos\*\* above. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [April 12, 2016, 1:37pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/75 "2016-04-12T13:37:53Z")
> [@agustincabreze](#): > > Your explanation seems fantastic to me. Possibly not the best description, as it implies fantasy rather than reality. > [@](#): > > I think that the IAS can be affected by the wind and its changes in direction and speed… Yes, if the wind is actually changing. > [@](#): > > if you take off with a headwind of 20 kts, and your aircraft flies at 70kts IAS, if you make a 180° slow change in your direction , getting a 20kts tailwind now … That’s not a change in the wind - it’s a change in the heading of an aircraft flying in a steady wind. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [April 12, 2016, 2:10pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/76 "2016-04-12T14:10:29Z")
> [@Chronos](#): > > … as the airplane turns it will lose some amount of airspeed. The amount of airspeed lost during a turn depends only on how abrupt the turn is. Yes, but it’s a bit more complicated. In a steady-state turn, the aircraft must generate more lift: Total lift required = Aircraft weight \* load factor Load factor = 1 + 1 / cos (bank angle) One way to do this is the way you imply: you gain the extra lift by an increase in angle of attack, yielding a lower airspeed. This is a good choice when your pre-turn airspeed was decently high. If your pre-turn airspeed was low, slowing down may be a bad plan - it can produce a stall, especially when you consider that in a turn your stall speed increases (by a factor equal to the square root of the load factor). The sensible alternative is to keep your airspeed acceptably high, either by making a descending turn or adding power. ---
**Author:** ![agustincabreze](https://avatars.discourse-cdn.com/v4/letter/a/ce73a5/32.png) [@agustincabreze](https://boards.straightdope.com/u/agustincabreze)\ **Post date:** [April 12, 2016, 2:11pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/77 "2016-04-12T14:11:06Z")
> [@Chronos](#): > > If the wind is steady, and the pilot is not spooked or tricked in some way by looking at the ground, then as the airplane turns it will lose some amount of airspeed. The amount of airspeed lost during a turn depends only on how abrupt the turn is. It does not depend on the speed of the wind, or whether the plane is flying upwind, downwind, or crosswind. If the airplane reverses direction within ten seconds, say, it will lose the same amount of airspeed if it’s flying in still air, or switching from upwind to downwind, or switching from downwind to upwind. Do you mean that change is due to the increased drag right?, As Richard Pearse wrote some pages behind. > [@Richard\_Pearse](#): > > I think the problems here come from mixing reference frames. You can either measure the aircraft’s motion relative to the ground or relative to the air it is moving through. If you try to use a mixture it doesn’t work and you get the wrong answer. When you talk about wind you are using the ground as a reference and should be using **ground speed** when referring to the aircraft, but when you are talking about airspeed you are using the air as a reference. > > Using your example I will first look at it with reference to the air and then separately with reference to the ground: > > 1. An aircraft is moving at 70 knots IAS through the air. It turns through 180º as abruptly as it can and is now travelling in the opposite direction at 70 knots IAS. It seems like there should be more here, but that’s it, that is the scenario in its entirety, any attempt to introduce wind speed is mixing the ground reference frame with the air reference. > > 2. An aircraft is moving at 70 knots IAS through air which is moving at 20 knots over the ground in the opposite direction as the aircraft. The aircraft has a **ground speed** of 50 knots. It turns as abruptly as it can and is now moving at 70 knots IAS with the 20 knot wind. The ground speed is now 90 knots. The aircraft has gone from 50 knots ground speed to 90 knots ground speed. Where does the energy come from to accelerate it from 50 to 90 knots GS and stop it from stalling? Answer, the wind itself. When viewed from the reference of the ground, the movement of the aircraft is the sum of the aircraft movement through the air and the air movement over the ground. > > So in example 1 there is no change in airspeed because the airspeed is measured only with reference to the air. What the air does over the ground is not relevant. > > In example 2 there is a change in **ground speed** and the energy required to achieve that change comes from the wind. The wind is relevant in this case because it is by combing the wind and aircraft vectors that gives resulting movement over the ground. > > Both examples are equivalent but viewed relative to different frames of reference. > > Remember, as soon as you start trying to relate the wind speed (ground reference) to changes in **air** speed (air reference) you are mixing reference frames and the answers become invalid. > > This all has the caveat that the airmass is steady, i.e, no movement of one bit of air relative to another bit. And that we are ignoring aerodynamic effects such as mentioned by \*\* Chronos\*\* above. So, basically, my thoughts are all wrong, right? I think that I have a big problem in visualizing the aircraft flying within the airmass, with no relationship with the Earth below or wind direction. And this: “cause in that sudden change the 20kts tailwind will try to push either your aircraft and the air that is in front of your aircraft pitot tube, but as that air is lighter than your plane, it is going to be “pushed” first. So, at that time, you will get your IAS decreased, until that tailwind (after some seconds or minutes) beats you aircraft inercia, where the IAS will recover its normal indication of 70kts.” is wrong, right? I f we consider no changes in the air mass, right? > [@Xema](#): > > Possibly not the best description, as it implies fantasy rather than reality. > Yes, if the wind is actually changing. > That’s not a change in the wind - it’s a change in the heading of an aircraft flying in a steady wind. Thanks for your explanation, it still keeps me thinking, cause I think my problem is that I can’t that wind direction or speed has no effect in the IAS if the planes flies in a steady air. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [April 12, 2016, 2:27pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/78 "2016-04-12T14:27:55Z")
Oops. In post #76, I screwed up the formula for load factor. It should be: Load factor = 1 / cos (bank angle) My apologies. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [April 12, 2016, 2:38pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/79 "2016-04-12T14:38:29Z")
> [@agustincabreze](#): > > I think my problem is that I can’t that wind direction or speed has no effect in the IAS if the planes flies in a steady air. It’s confusing for nearly everyone. It’s hard to accept that the air you can’t see is what matters, whereas the ground you can see - and which has been the frame of reference for all your motion since the day you were born - is largely irrelevant. There’s a good chapter in _Stick and Rudder_ (classic 1944 book on flying by Wolfgang Langewiesche) that has helped a lot of pilots understand wind. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [April 12, 2016, 5:21pm UTC](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386/80 "2016-04-12T17:21:45Z")
And all this is why, if you are going to fly low & slow, (pipeline patrol, Ag flying, strip photography) anything where you you are out of altitude, airspeed and most of your power and still must make a fixed ground track, 99.9% of pilots who enter this kind of work or fly marginally powered aircraft of any size in mountains near to or below surrounding ground tops need to learn stuff that is counter to all their life training and most of their flight training. If they don’t, they don’t last long in that business and a depressing number get dead. Instinctual flight control movements are/can be really really life threatening under these forms of flying. _Old because I was lucky to survive the bold part_ [Previous page](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386.md?page=3) [Next page](https://boards.straightdope.com/t/aircraft-turns-from-headwind-to-tailwind-loss-of-ias/522386.md?page=5)