So, I understand finding floors and such when seeing something a fraction like 45/10 or 39/SFC, but I've been reviewing and gotten a couple of questions that look like this:

What is he floor of the controlled airspace overlying the Coeur D'Alene Airport?

The answer is "At the surface" but I can't figure out where it says that? The second question said this:

What is the floor of the controlled airspace overlying the Sandpoint Airport?

The answer is "700 feet MSL". Cant find that either.

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It does not say it anywhere because the answer is not variable like class B airspace but lets dig in.

The question here is really trying to get you to identify the airspace that surround Coeur D'Alene Airport and we can see the dashed magenta line encircling it. If you take a look at the legend you will see that denotes

Class E (sfc) Airspace.

The same goes for Sandpoint Airport which is surrounded by a faded magenta line. The legend again denotes

Class E Airspace with a floor 700ft. above the surface

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The controlled airspace around Sandpoint begins at 700 ft AGL. The elevation of Sandpoint Airport is 2131 ft MSL as indicated by the airport data. The floor of controlled airspace needs to be in terms of MSL which would be the airport elevation + the start of the Class E airspace or 2131 ft MSL + 700 ft AGL = 2831 ft MSL.

I don't understand why the answer would be 700 ft MSL.

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  • 1
    $\begingroup$ The logical explanation based on the premise and the asker accepting the above surface answer, is that they made a typo while asking here. $\endgroup$ – ymb1 Jun 18 '19 at 22:01

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