SAAB 340A Ground Speed vs IAS

[PNut]

Problem 1

 

 

All of a sudden the altitude set numbers are not lined up. Is there a way to correct this?

 

 

Problem 2

 

 

IAS = 179 kts

 

Head Wind approx. N.E. = 47 kts

 

GSP = 189 kts

 

How is it possible to have a faster GSP with a headwind? (see attachment)

[niebieski]

Problem 2

 

https://en.wikipedia.org/wiki/Airspeed

Edited January 15, 2016 by niebieski

[PNut]

Sorry still don't get it.

 

Assuming IAS = 180 kts with 0 kt wind = TAS = GSP = 180 kts.

 

With a head wind of say 30 kts, wouldn't the GSP be lower, say 150 kts?

[niebieski]

Allow me to quote Wikipedia (the link i provided earlier):

 

True airspeed differs from the equivalent airspeed because the airspeed indicator is calibrated at SL, ISA conditions, where the air density is 1.225 kg/m³, whereas the air density in flight normally differs from this value.

 

For some reason you're thinking IAS = TAS in no wind conditions?

(by the way, TAS is displayed right above GS on the EHSI)

[Ubbi]

Sorry still don't get it.

 

Assuming IAS = 180 kts with 0 kt wind = TAS = GSP = 180 kts.

 

With a head wind of say 30 kts, wouldn't the GSP be lower, say 150 kts?

Your assuming is wrong!

If the temperature gets higher or you are flying higher, the air around you will loose pressure! (Thats why your altitude indicator shows some climbing)

But your IAS is a differential pressure gauge with the pressure reading expressed in units of speed. So if the temperature is rising or you are going up the IAS will read to slow!

 

So at high altitudes you true Airspeed is much more than your indicated airspeed.

Your IAS is only correct at ground level with standard meteorological weather (ISA conditions).

[PNut]

Thx!!!!!!!