Anyone has a simple table that converts IAS to GS? Or do I real have to buy a TI calculator to pre-input the formula to figure out what the GS is? Thnx.

Indicated airspeed to groundspeed conversions also take consideration of winds. You might first convert to true airspeed (KTAS) and a simple rule of thumb is add 2% for every 1,000 feet altitude. You will need to know what the winds are at your flight altitude and the drift correction to figure the affect of those winds on the KTAS to get your GS. An E6B calculator would give you the tools to figure all of this out and there are several ones you could download. I don't recall the aircraft right now but I downloaded one that came with a really neat depiction of a rotary slide E6B that was a popup gauge. If you own any payware aircraft from Aerosoft they offer a free gift to customers of a nice aviation calculator.

GS = TAS - Headwind(you can get the TAS off of the IAS guage of a Cessna 172 for e.g.)You can even calculate it backwards if you don't know the headwind. For planning purposes you should know your Headwind from winds aloftIf you are in the plane flying.1. Get your TAS (from the IAS guage). e.g. 140kts2. calculate how long it takes to go from point A to Point B in your sectional and calculate GS. (I flew 10 kmiles in 5 minutes means 10/5 * 60min = 120. GS = 120kts)3. use that to calculate your Headwind. 140 (IAS) - 120 (GS)= 20kts.an Aside:I have flown a Cessna 172S backwards. Long time ago, my CFI took me up on a windy day... It was like 60 kts at 6000 feet and he made me point the plane exactly towards it and asked me to show him slow flight. I was mushing at 45-50kts and he showed me the GPS... showing that I was headed in the opposite direction. I could see the ground moving forward. Manny

>I was mushing at 45-50kts and he>showed me the GPS... showing that I was headed in the opposite>direction. I could see the ground moving forward. I once saw a bird doing that. It was facing directly into a headwind and gliding backwards. Pretty cool sight.

Back in the '70s when I was taking my PPL lessons in April (near Minneapolis) I saw instructors fly out to "rescue" student pilots who got lost and were running low on fuel in their Cessna 150s which are pretty slow aircraft. They did not allow enough reserve fuel taking into account strong headwinds and any route miscalculation led to no margin. I saw the instructor leading the lost one on final and just before the lost duckling crossed the threshold the engine quit. He landed firmly but safely and had to be towed off the runway.

>An E6B >calculator would give you the tools to figure all of this out>and there are several ones you could download.I have noticed that there is discrepancy between FS and the E6B computed values as you start getting higher on the flight levels. Dunno why, but it can be substantial..regards,Macs :)

Ouch, talk about pucker factor for all involved.

Hello Bo,I have posted IAS, TAS & EAS tables on Herves Web site look for International Standard Atmosphere tables.http://perso.wanadoo.fr/hsors/FS_Soft/index.htmlIan

Thank you.

I am always pleased with thanks when all the work preparing the answers is so much appreciated.Enjoy,Ian

Hi,Yes, there apears to be an error in the IAS to TAS calculation in FS. When I calculate it on the E6B it comes out different for me as well.Hope this helps,--Tom GibsonCal Classic Propliner Page: http://www.calclassic.comFreeflight Design Shop: http://www.freeflightdesign.comDrop by! ___x_x_(")_x_x___

<>Any instructor who takes a student up in a 172 into 60 kt winds should have his licensed revoked permanently....IMHO.Regards,Jim

><like 60 kts at 6000 feet and he made me point the plane>exactly towards it...>>>>Any instructor who takes a student up in a 172 into 60 kt>winds should have his licensed revoked permanently....IMHO.>>Regards,>JimWhy Jim? You just won't get anywhere going into the wind particularly fast. However going away from it you'd be in heaven, that's gonna be the fastest 172 on the block. :)