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In aircraft literature, what does cross-track and along-track wind directions mean? Please explain in terms of the aircraft's motion relative to the wind direction. I can hazard a guess: along-track is wind in the direction of the aircraft's velocity, and cross-track would be perpendicular side-to-side (or is it top-bottom) wind direction wrt to aircraft velcoity direction? Not sure...some explanation and clarification would help. Thanks.

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""In aircraft literature,"" So, why You ask here? As most readers here You can English good enough to derive the "obvious" meaning, if there is a special meaning among aircraft people, then asking here is unwise. Vote to close as off topic –  Georg Jun 6 '11 at 13:17
@Georg: "You can English good enough.." Lol. –  qftme Jun 6 '11 at 16:33
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1 Answer

up vote 2 down vote accepted

The "track" is the intended travel path over the ground from the origin to the destination. Cross-track wind is the wind perpendicular to this line (crosswind), and along-track wind is the headwind/tailwind component.

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What differs in Your "answer" from what Rhea already knew? –  Georg Jun 6 '11 at 13:34
@Georg I am not sure what's the problem in getting clarified about the meaning of "cross-track wind" & "along-track wind" from someone who might know better...as I said in the OP, I could not find a definitive meaning of what the terms meant, I was only making a guess and I could be wrong. Nibot thanks for clairfying the meaning. –  Rhea Jun 6 '11 at 16:34
It's important to note that it's with respect to the path from the origin to the destination, and not the aircraft velocity. Depending on the application, the "origin" might be continuously redefined as the aircraft's current position. Furthermore, when talking about aircraft velocity, you have to be clear whether you're talking about airspeed or groundspeed. –  nibot Jun 7 '11 at 3:46
Sorry I should have asked it in more accurate words...yes I meant that it should be measured with respect to the aircraft's instantaneous position and not velocity... Would the cross-track wind measurement/direction change if it was measured with respect to the aircraft's 'airspeed' velocity than 'groundspeed' velocity? -- as the cross-track direction is effectively perpendicular to the instantanous velocity of the aircraft -- whether measured wrt to ground or air -- so its measurement/direction would not be infulenced by the aircraft's velocity... no? –  Rhea Jun 7 '11 at 18:10
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