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280 knots indicated airspeed (KIAS)? What's your groundspeed (GS)?

Marko Milivojević

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OK, so. In very short words. Also, I am going to lie to you, but it's for your benefit. As you learn more, you will realize how wrong what I wrote below is, but that's OK.

The speed you are seeing on the PFD (left screen) is something called indicated airspeed (IAS; or knots indicated airspeed: KIAS). While we call it speed, it actually measures differential pressure between static input (a hole on the side of airplane), and dynamic pressure (a hole in front which sucks up air as the plane is moving forward). What this differential pressure shows is dependent on the density of the surrounding air. As you probably know, there is more air closer to the ground you are. As you go higher, there is fewer air, therefore the amount of pressure that air can exert is lesser. This is why you are seeing "low speed". What you are *really* seeing is "low pressure".

So, this is why we have things like TAS (true airspeed; which is important, but you "don't care" about it), or the indicated speed adjusted for pressure and temperature. The speed the aircraft is moving when compared to the ground is called "ground speed", or GS. You can see it indicated in the upper left corner of your second screen from the left. This speed is the combination of TAS and wind, and is the speed you seem to care about.

As you learn more, you will realize that it's really just CAS (calibrated airspeed) you care about, but that gets even more complicated ;-).

Oh, and one more thing. Please note that this is PMDG support forum. Their rules require you to sign all messages with your full name. Please, do that. Thanks!

Edited by icemarkom
Minor typo fixes.
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Marko Milivojević

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Have you got the doodah in the "on" position? Also, make sure that the thingamabob is set to "active", or else you'll find yourself on an inclined plane wrapped helically around an axis. :P

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Matthew Bellette

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42 minutes ago, martino2706 said:

whats that? i just start flying on pmdg before i used just basic plane so iam just learning


Start with the Tutorial.  If you are new to aviation this is all but mandatory.  Also, get a copy of the FAA Airman Information Manual (AIM), which will be your bible as you learn the basics, free here: https://www.faa.gov/air_traffic/publications/

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Dan Downs KCRP

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56 minutes ago, martino2706 said:

hi. why is mine max crz speed only 280?

Hi Martino2706.  Welcome to the PMDG forums.

Please read through this thread, and try to ignore the smart-alecky stuff.  There's some useful information on your question here:

Also, PMDG wants you to sign your full, real name in its forums.




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