Part 107 Airspace 2026: Reading a Sectional Chart

If you take one thing away about Part one oh seven airspace, take this. Every altitude printed on a sectional chart is measured from sea level. Your four hundred foot limit is measured from the ground under your feet. Mix those two up and you will fly into controlled airspace convinced that you are clear of it.

That is not a trivia point. It is the most common way a remote pilot ends up inside Class C or Class D with no authorization, and the knowledge exam tests it directly. So let us build the whole thing from one idea. By the end you will be able to look at any ring on a chart and answer the only two questions that matter: what class is this, and do I need permission?

Start with the two abbreviations. MSL means mean sea level: height measured from the surface of the ocean. AGL means above ground level: height measured from the dirt directly beneath you. Charted airspace floors and ceilings are always MSL.

Your Part one oh seven altitude limit is always AGL. Those two numbers only agree in a place where the ground itself happens to sit at sea level, which is almost nowhere. Now the chart. Airspace class is drawn with just two variables, color and line style, and once you know the four combinations you can read any sectional.

A solid blue ring is Class B, the airspace over the busiest airports. A solid magenta ring is Class C. A dashed blue line is Class D. And a dashed magenta line is a Class E surface area.

Class G is the one that is never drawn at all — you identify Class G by the absence of everything else. Inside those rings you will find numbers stacked like a fraction. Forty-one over thirteen means a ceiling of four thousand one hundred feet, over a floor of one thousand three hundred feet. Both in hundreds of feet, both MSL.

Class D is written differently: a single number in a segmented box, like minus twenty-five, where the minus sign is chart shorthand for from the surface up to but not including two thousand five hundred feet MSL. And here is the rule that all of it generates. Part one oh seven point four one says you need prior air traffic control authorization to operate in Class B, Class C, Class D, and inside the lateral boundaries of a Class E surface area. In Class G you need none.

In practice you request that authorization through LAANC. So the ring you are standing under is not decoration on a map. It decides whether you are legally allowed to take off. Let us test it.

First question. A sectional shows an airport ringed by solid magenta lines, and the outer shelf carries the figures forty-one over thirteen. What is the floor of that shelf? Option one, one hundred thirty feet AGL.

No — that is off by a factor of ten and it uses the wrong reference. Option two, thirteen thousand feet MSL. No — you have added a zero; the figures are hundreds of feet. Option three, one thousand three hundred feet MSL.

That is correct. Option four, one thousand three hundred feet AGL. The number is right and the reference is wrong, and that is the trap the whole lesson is about. Second question.

You plan to fly at a non-towered airport that the chart encloses with a dashed magenta line. What does that require? Option one: it is a Class E surface area, so you need prior air traffic control authorization. That is correct.

Option two says Class E starting at seven hundred feet AGL, so nothing below that needs authorization — wrong, because that is the faded magenta band, not the dashed line. Option three calls it advisory only and says a visual observer covers you. A visual observer is never a substitute for authorization. Option four calls it Class G.

It is not: a dashed magenta line is controlled airspace all the way down to the surface, and no control tower does not mean no controlled airspace. Third question, and this is the one the whole lesson was built for. Your launch site sits at a field elevation of one thousand feet MSL, directly under a Class C shelf charted forty-one over thirteen. You climb to four hundred feet AGL.

What is the situation? Option one says the floor is one thousand three hundred feet AGL, so you are still in Class G. Wrong reference again. Option two says you are at four hundred feet MSL and well below the floor — that would only be true if the ground were at sea level.

Option four says fourteen hundred is still below thirteen hundred, which is just arithmetic backwards. Option three is correct: one thousand feet of field elevation plus four hundred feet AGL puts you at one thousand four hundred feet MSL, which is one hundred feet inside the Class C shelf, and you need prior authorization. Read that one again, because it is the whole point. Nothing about the aircraft changed.

You flew a perfectly legal four hundred feet AGL. The airspace changed around you because the ground was high. Any time the terrain sits high relative to a charted floor, do the addition before you launch, not after. So remember.

Charted numbers are MSL, your limit is AGL, and you add your field elevation to convert. Solid blue is Class B, solid magenta is Class C, dashed blue is Class D, dashed magenta is a Class E surface area, and Class G is whatever is left over. Authorization is required in B, C, D and Class E to the surface, and you get it through LAANC. Class G needs nothing.

Practice this on real questions, free, at quibank.com/en/part-107. Airspace, regulations, weather, loading and operations, in English, Chinese and Spanish, with no sign up.