IAS vs MPH - manual is confusing

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Paughco
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Posts: 2096
Joined: 30 Nov 2014, 12:27

Re: IAS vs MPH - manual is confusing

Post by Paughco »

Gabe: You might want to download the Pilot's Handbook of Aeronautical Knowledge from the FAA website: https://www.faa.gov/regulations_policie ... tion/phak/. Then take a look at the definition of indicated airspeed on page G-15 (near the back).

"Indicated airspeed (IAS). Shown on the dial of the
instrument airspeed indicator on an aircraft. Indicated
airspeed (IAS) is the airspeed indicator reading uncorrected
for instrument, position, and other errors. Indicated airspeed
means the speed of an aircraft as shown on its pitot static
airspeed indicator calibrated to reflect standard atmosphere
adiabatic compressible flow at sea level uncorrected for
airspeed system errors. Calibrated airspeed (CAS) is IAS
corrected for instrument errors, position error (due to
incorrect pressure at the static port) and installation errors."

Then, on page G-31,

"True airspeed. Actual airspeed, determined by applying a
correction for pressure altitude and temperature to the CAS."

Note: Pressure altitude is the altitude you get when you set your altimeter to 29.92 inches of mercury.
There's all sorts of interesting aeronautical stuff in that handbook. Oh yeah - almost forgot. Everything you want to know about anything is available on the Internet. Here is the Wikipedia description for True Airspeed: https://en.wikipedia.org/wiki/True_airspeed. Here's a YouTube video on calculating true airspeed: https://www.youtube.com/watch?v=mQBaj1f5SS4.

There's tons of useful flying info on YouTube! As a long-time sim pilot and a lifetime airplane enthusiast, I am very happy that our sim experience is getting closer and closer to the real deal.

Seeya
ATB :)
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