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Guest Martin

IAS, TAS, GS???? Errors everywhere?

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I have always had trouble reconciling the various panel/screen indications of indicated air speed (IAS), True airspeed (TAS) and groundspeed (GS) .Could somebody please explain to me the numbers at the top of the screen when Shift-Z is pressed - especially the numbers to the far right of the line.Thanks Barry

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Hi Barry,I'm not sure if this is the aswer you're looking for:On the red script at the top of the FS screen:Alt 71 feet, Airspeed 23.2 knots, wind 12 knots from magnetic heading 102.The panel also indicates 23 Knots. At this low altitude (71 feet), TAS is almost identical to IAS. The two only diverge as a function of air density as you get higher. However, since your heading is 100, the 12 knots is virtually all headwind component, and will contribute to both IAS and TAS readings. Ground speed, therefore, is 23.2-12; around 11 knots in this case (I assume you were taxying?).Bruce.

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>Hi Barry, >>I'm not sure if this is the aswer you're looking for: >>On the red script at the top of the FS screen: >Alt 71 feet, Airspeed 23.2 knots, wind 12 knots from >magnetic heading 102. >>The panel also indicates 23 Knots. At this low altitude (71 >feet), TAS is almost identical to IAS. The two only diverge >as a function of air density as you get higher. However, >since your heading is 100, the 12 knots is virtually all >headwind component, and will contribute to both IAS and TAS >readings. Ground speed, therefore, is 23.2-12; around 11 >knots in this case (I assume you were taxying?). NO-- herein lies the problem. I was stationary on the runway heading 100 with the wind set to 24knots from direction 100. These numbers do not seem to make sense. Barry

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>NO-- herein lies the problem. I was stationary on the runway >heading 100 with the wind set to 24knots from direction 100. Then your TAS is 24 knots. (The air is coming at you at 24 knots so your True Airspeed is 24 knots.)Martin767 fetishistIt's a lot like life and that's what's appealing

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HI Barry ! It is very easy : IAS is actually not a speed at all It's a drag, the air creates when you are trying to move through it. That's the pressure, which hits the plane from the outside. IAS however standardized the way, that at the Mean Sea Level it will become your " real speed "TAS is a speed. It shows, what your speed would be if you were moving at 0 (MSL) altitude in NO WIND condition. The TAS=IAS at MSL. finally GS is like TAS, but it also counting the wind. So this is the speed, which actually brings you to your destination . regardsOleksiy

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Another notice. That speed at the top of the FS screen is a bit tricky :When you are on the ground, it shows the ground speed (GS)If you are above the ground, it will switch to IAS.Oleksiy.

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>When you are on the ground, it shows the ground speed (GS) >If you are above the ground, it will switch to IAS.I think it displays IAS on the ground too, because I'm sure I've seen it read zero when I was moving, and more than zero when I was parked.Martin767 fetishistIt's a lot like life and that's what's appealing

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