What does it mean when the wind component for a flight is 75mph (headwind)? Is the plane actually flying through 75mph winds? How is the wind component actually calculated?Sincerely,Chris

>What does it mean when the wind component for a flight is >75mph (headwind)? Is the plane actually flying through >75mph winds?Yes! Think about it this way: if you throw a matchstick into a pond and the current is moving east - the matchstick moves east along with the current and it moves at the same rate as the current. Imagine that matchstick is powered and is moving north. If its speed is equal to the speed of the water then the matchstick will actually travel in a northeast direction because its forward (northerly) movement is partially offset by the movement of the current. If the matchstick were to be moving east, then its speed (groundspeed) would be doubled, and if it were to be moving due west, it would remain stationary in the water because its forward (westerly) motion is offset by the easterly movement of the water.The same for an aircraft - it flies in a "current" of moving air. If you are flying west at FL350 you might encounter a wind out of the west (270) of say 100 knots. That amounts to a 100 knot headwind. If that wind were from 315 at 100 knots (45 degrees off the nose on the right) then apply trigonometry and the headwind is 100/1.414 or ~71 knots. In this case, the headwind component is equivalent to a 71 knot wind directly on the nose. However, there is also a 70 knot direct crosswind component which requires a nose-right heading correction to maintain the desired course over the ground. (That's another discussion!).So yes - a 75 knot headwind component is effectively the same as flying through a wind of 75 knots directly on the nose of the aircraft.As an aside: back in my C-150 student pilot days, I remember flying along I-85 in Alabama heading from MGM to 06a (Tuskegee - Moton Field)and watching the semi's outrunning me. I was flying with an indicated airspeed of ~80 mph and with a ~15 mph headwind my groundspeed was ~65. Those trucks were doing at least 70!Hope this helps out.-michael

>75mph winds? How is the wind component actually calculated? You get this info from preflight weather information (winds aloft forcast) - if you have the heading you can compute whatever component you want (simple trigonometry)ORthe FMC calculates the wind for you once in flight (you must have seen it on your 757).Michael J.

If that wind were from 315 at 100 knots (45 degrees off the nose on the right) then apply trigonometry and the headwind is 100/1.414 or ~71 knots. In this case, the headwind component is equivalent to a 71 knot wind directly on the nose.I guess I don't remember trig. that well - how did you get the #1.414 - what does it represent? What exactly is the formula I use - Wind divided by........ ?Also, when you are done doing the math, what does the final numeber indicate - in other words, how can you tell if your final number (in this case 71 knots)is a headwind or a tail wind?Finally - winds can actaully be as strong as 100mph up at FL350?Thanks a ton guys! I feel like I alomost have it!Sincerely,Chris

Yes, I have seen it on my 757, but I actually wanted it before I flew, so I can compute more accurately my fuel consumption. Lately, I have been acting as my own flight dispatcher and am trying to be as accurately as possible. I know in the real world, all this would be done for me.Also - SIMPLE trigonometry?! :-) Easy for you to say! you weren't absent that day in school! :-lol I would never use the word simple when it comes to Trig. although others may! :-)Thanks,Chris

Chris ->Finally - winds can actaully be as strong as 100mph up at >FL350? Absolutely! During World War II, when B-29's encountered the jet stream during missions over Japan, they would sometimes find themselves making "negative ground speed", i.e., the bomber was moving backward relative to the ground. The B-29 cruised at about 250 mph, and had a top speed of about 350. The only option in such a situation is to change altitude and/or heading. Needless to say, this gave the crews fits, as it complicated the navigation, screwed up bombing accuracy, and often made for a very rough flight.- Dave Reed

Hi Chris,Here are two equations that you can use with any scientific calculator you happen to have handy (even the one supplied with windows will work)...First, subtract your heading from the wind's heading, call it "A".Second, call the wind velocity "V". Then, your head/tail-wind is V * cos(A) and your crosswind is V * sin(A). If your head/tail-wind number is positive it's a tailwind; a headwind, otherwise. If your crosswind is positive it's coming from starboard; port, otherwise.Here are a couple of examples, using windows calculator and copy/paste:Aircraft Heading = 240Wind Heading = 315Wind Velocity = 30A = 75sin(A) = 0.9659258262890682867497431997289cos(A) = 0.25881904510252076234889883762405tailwind = 7.7645713530756228704669651287214starboard crosswind = 28.977774788672048602492295991867Aircraft Heading = 170Wind Heading = 5Wind Velocity = 25A = -165sin(A) = -0.25881904510252076234889883762405cos(A) = -0.9659258262890682867497431997289headwind = -24.148145657226707168743579993222port crosswind = -6.4704761275630190587224709406012Oh yeah, I almost forgot. The 1.414 figure that was quoted in one of the prior posts is one of those "standard" numbers you're supposed to remember but rarely ever do. It comes about as sin(45) = 0.7071. Then, invert that number, i.e., find 1 / sin(45), to get 1.414. Here's a quick table:

 x	 sin(x)	 cos(x)	1/sin(x)	1/cos(x)------------------------------------------------  0	0.0000	 1.0000	   NaN	   1.0000 30	0.5000	 0.8660	 2.0000	  1.1547 45	0.7071	 0.7071	 1.4142	  1.4142 60	0.8660	 0.5000	 1.1547	  2.0000 90	1.0000	 0.0000	 1.0000		NaN120	0.8660	-0.5000	 1.1547	 -2.0000135	0.7071	-0.7071	 1.4142	 -1.4142150	0.5000	-0.8660	 2.0000	 -1.1547180	0.0000	-1.0000	   NaN	  -1.0000210   -0.5000	-0.8660	-2.0000	 -1.1547225   -0.7071	-0.7071	-1.4142	 -1.4142240   -0.8660	-0.5000	-1.1547	 -2.0000270   -1.0000	 0.0000	-1.0000		NaN300   -0.8660	 0.5000	-1.1547	  2.0000315   -0.7071	 0.7071	-1.4142	  1.4142330   -0.5000	 0.8660	-2.0000	  1.1547360	0.0000	 1.0000	   NaN	   1.0000

Notice that you only really have to remember 3 numbers and then how to sequence them. I find the scientific calculator method far more satisfying, though, because I get soooooo many more digits of precision. :-)Happy trigifying!Cheers, Tony

Chris,It would actually be WRONG trying to use trigonometry to calculate winds for your flight planning.These are only predicted winds so they already are at best - a good guess. You should use common sense and assume the worst winds for your trip. If I were say planning a trip in a 757 across USA I would "eyeball" the winds on a meteorological chart for winds aloft and came up with the worst case. If winds were really bad I wuld consider even flying to the north or south to either avoid bad headwind or take advantage of a good tail wind. Unfortunately without a sophisticated software you could not do such fancy planning effectively. But you can still "eyeball" winds, get some reasonable number, calculate your fuel and still carry a 90-min reserve. I am not sure if in this sim world such careful fuel planning makes any sense at all. And in a 757 you are not really flying long stretches over water so even if you end up short on fuel you can always find a suitable airport.Michael J.

Couple of new questions:OK - assuming I use common sense (which I have never been known to do! :-)), when you eyeball the winds on a chart, how can you tell what a "worse case" number would be? For example, do you double the number that exists currently? Or..... can you recommend reasonable, common sense wind component numbers for each of the 8 basic compass directions of flight (ie - flying North, flying South, Flying East , flying West, flying NE, SE, SW, NW)? I guess if I could just use reasonable numbers for each of these 8 basic directions, it would probably suffice for the sim, & then I can start to put this topic to rest. What do you think? Just want to know a good way to account for the wind in basic ways.Also, than you Michael for all the great info. I really appreciate all the help from both of you.Sincerely,Chris

Chris,If you try to fly 757 you should at least posses knowledge of a private pilot, don't you think ? And so concepts like wind correction angle, TH (true heading), MH (magnetic heading), CAS, TAS, true course, magnetic course, ground speed, etc. should be familiar to you like a morning prayer .. ;-) When I said "eyeball" I assumed someone who can quickly (through experience) tell the wind correction angle and the worst case scenario for the ground speed. Therefore in your pursuit of aviation knowledge I urge you to grab some textbook on aviation (Rod Machado's classic is an obvious choice) and get to know little bit more about winds and how they affect your flight. You really owe it to yourself and do what most of us did in the past - grab tea or coffeee, plunge in your favorite armchair and just .. study. There is no escape from it .. not for someone who wants to fly 757.*:-*Michael J.

>Oh yeah, I almost forgot. The 1.414 figure that was quoted >in one of the prior posts is one of those "standard" numbers >you're supposed to remember but rarely ever do. It comes >about as sin(45) = 0.7071. Then, invert that number, i.e., >find 1 / sin(45), to get 1.414. It's also derived directly from the equation for the length of the sides in a right triangle: C^2 = A^2 + B^2. When a and b are equal length, each of their lengths are c/{square root of 2}. (That's why I chose that example :-))Once upon a time, I had to do this stuff using a slide rule (that's why *I* have not forgotten ;-) )-michael

Believe it or not, I actually recieved Rod Machado's book 6 weeks ago as a gift! I had not started reading it yet - until today! I love it! (I momentarily cheated by skipping ahead to Chapter N about flight prep so I could read my about wind questions :-)). It looks like it is a terrific book! Excellent diagrams. I specially like the way he compared flying in wind to swimming in a current of water. This really helped me to understand wind angle correction. Thanks for the inspiration to finally break the seal on the book.One last question now that I have a better understanding of this wind topic - if I am eyeballing a meterological chart showing winds aloft, and you say I can determine the "worst case" - I presume when you say "worst case", you mean the worst case of winds, or most challenging winds aloft that I would encounter along my route that day. Yes?If I know what my "worst winds" for the day are going to be (& the direction), I presume I can then come up with a reasonable wind component number to plug into my fuel consumption planning. Does this sound reasonable? Since it is just a sim, I can probably do just fine, especially if I carry a 90 minute reserve. Besides, this might be easier than Trigonometry! :-)BTW - you said that the 757 does not fly long stretches over water - is that because it cannot carry enough fuel to fly REALLY far (ie - to Japan)? I presume Europe would not be out of the question though?Too bad that Fly2 does not seem to interpret imported Metar files with winds aloft - it seems to apply the same wind speed & direction to every altitude - no matter how high or low, every altitude level seems to carry the same wind direction & speed.Finally - point well taken about learning basics before flying the 757. For me, I adore the big heavies, & this is only fun for me. For me, I have read a ton of material, yet I know there is no substitute for learning foundations first. I do the best I can for someone who is not a pilot. I just love this stuff so much but can't afford flight lessons with a ton of financial knocks in life. Besides, to learn this as a career - I'm already 35. Kinda' late to begin something new now, especially when I have a teaching career that I love so much. For me, I have suffered tremendous personal pain & suffering over the last three years, so I try to find healthy escapes like flight sim when I am able. I truly understand your point - I am just trying to have fun. Thanks for your patience & incredible knowledge. At this painful & sad time in my life, it means a great deal to me.Sincerely,Chris

Chris,I am only hours from a trip with my family, have no time for long posts.757 - it is the range. I think Icelandic flies them between Europe/USA and Iceland - this is the longest stretch for them probably.I don't do any wind analysis (in the sim) - just carry so much fuel I will always make it. I like to practice landings being on the heavy side anyway. My only problem is not to carry so much fuel that my landing weight will be too high :-lolI am glad you got the book. You don't have to read it from A-to-Z. Just the stuff you need.Michael J.

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All I can say is ........ WOOOOOOOOOOOOOOOOOOOOOOOOOW!!!!!!!!!!!!! :-)THanks!!!!!!!Chris