airspace question


Well-Known Member
Ok, so I finally hit the airspace chapter... Geez thats alot to take in!

My question is, over Denver International Airport the Class B airspace goes from sfc to 12,000 MSL. Am i to believe that the space between 12,000MSL and and 14,500MSL is Class G airspace? Or is this considered Class A airspace and I have no business taking my 172 up there?

Thanks if anyone can answer this, Tim
It would more than likely be E class from 12,000 to 14,500 MSL. Usually Class E extends from 17,999 down to 1200 or 700 AGL over populated areas. I've never looked at a denver sectional so I can't so for sure. Look for that Blue Faded Line, if there is one. If the line is fading towards denver, then the airspace you refer to is class E.

The blue faded line will probably be found somewhere near the mountains (if it's there), because it indicates whre the Clss E steps down to 1,200 from 14,500.
Ahhh, that actually helped me understand it some... It has the Magenta line indicating class E 700' and above. I now see where they get the "everywhere else" training aid from.

So if i want to i can go fly over DEN as long as i stay over the class B ceiling at 12,000 ft and dont get too high into Class A.
I don't think class A will be a problem (FL 180) in a 172...Unless of course you got the rocket outrigger option.
Oops yeah good catch... class A only goes down to 18,000MSL but then that leads me to another question. If Class G can only go as high as 14,500MSL (according to my textbook) then what is between the top of the highest Class G airspace and the bottom of Class A? (between 140 and 180)

I am loving this kind of studying, beats the hell out of shakespeare!

Thanks again guys!
14,500 MSL to 17,999 MSL will be Class E, unless the terrain is higher than 14,500 MSL, in which case class G will extend from the surface to 1,500 AGL with class E extending from the top of the class G to the bottom of class A.

For instance say you have a 15,000 ft peak. The airspace will be Class G from 15,000 ft MSL to 16,499 MSL then Class E from 16,500 MSL to 17,999 MSL, and of course Class A 18,000 and above.

Anybody feel free to correct me if I'm wrong.
well i dont think i would want to go up to 180. the air may be a little too thin for this coloradan. I dont mind up to 140 but after that, considering what you are doing, i think you are pushing it without oxygen. Some of my hiking trips have gone a bit higher up than FL140. There has to be some kind of FAR for that. I hope people arent allowed to fly up to FL180 without some oxygen.
regs state that the required crew must use oxygen for any duration of more than 30 minutes spent above 12,500 MSL. Oxygen must be used for any time at all above 14,000 MSL, and even passengers have to be provided with oxygen above 15,000 MSL.

Thanks man, that makes perfect sense to me and i think you are right on. Then again I was just introduced to this stuff today?

Thanks again, Tim
ahh, and then the reg too. Thanks!

So i can fly over the class B of DEN as long as i stay between FL120 and FL125.

That is kinda odd that the reg is that low. I wonder if they suggest i take oxygen with me on my hikes on Mt Evans? It is well over 14,000'. I suppose they are thinking more about people who live near sea level and this would have a greater effect on.

Darn flatlanders screw it up for us mountain folk.
Yeah, mountain folk could probably handle 14,000 but the FAA even *reccomends* that you use oxygen on flights above something like 5,000 or 6,000 MSL at night, and I think 10,000 during the day. Like you say, they probably came up with these reccomendations to cover themselves with everyone, including people who live at or near sea level. The specific reccomendation is in the AIM somewhere but I'm not sure what chapter.
As you learnt here, you have to remember all the regs, and many can be an factor all at the same time.

It seems that you were planning to get from one side of DEN to the other, why not just request a clearance from center? Many people go out of there way to dodge class bravo, and really never consider tuning on frequency and asking to transition class bravo. Yes you will need a clearance, and probably will be vectored over the airport but it sure beats flying around it. If it is busy they might not grant you a clearance, but the one time Ed and I were going up to Big Bear and wanted to fly direct (chopping the edge of LAX class Bravo) they did not seem to have a problem with it (even though I believe we never actually entered class Bravo).
haha, i live around 5,500' here north of Denver, i guess i better get my oxygen tank.

I think most of the ski areas go up to 13,000' or so and its always fun to talk with the people that come up from San Diego and such. They are almost dead by the time the gondoloa/lift gets us to the top.

I actually took a course about high altitude/mountain climates. It is easier for younger people to get acclimated to high altitudes but once you get over about 25 you may as well hang it up. Also i forget where but there was a group of natives somewhere in south america that were known for living at very high altitudes (over 10,000') and their chest cavities were all consistantly larger than the average human's.

If you ever get a chance, i highly reccomend "mountain weather & climate" by Roger G Barry.

Thanks again for the info!

14,500 MSL to 17,999 MSL will be Class E, unless the terrain is higher than 14,500 MSL, in which case class G will extend from the surface to 1,500 AGL with class E extending from the top of the class G to the bottom of class A.

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I thought Class G was from the surface to 1200. Class E is above 1200 ft AGL. Is it different in mountainous regions? Or am I missing something?
Yeap airspace can be pretty confusing, however once you get your head around it, it is quite straight forward.

I have landed at LAX a few times and had no problems there, so I can not see you having any probs. We have special flight rules areas over LAX so getting clearances and not going through that area probably not going to happen.
I found out from my CFI during a review for the commercial oral that I didn't know everything I should about class G & E airspace. I usually didn't give class G and E much thought but there are some little details that I never quite learned properly until a few weeks ago. Here are some things that were explained to me.....

The height of Class G airspace can vary greatly.

Unless otherwise indicated on the sectional, class G airspace extends from the surface to 14,499 MSL. Class E extends from 14,500 MSL to 17,999 MSL, and class A extends from 18,000 up (FL 600 I believe). Before reviewing this subject again with my CFI, I was under the impression that class E automatically began at 1,200 AGL. This is apparantly incorrect. It does in fact begin at 14,500 MSL unless otherwise indicated by one of the items below.

A fading blue line on a sectional indicates that that Class E begins at 1200 ft AGL on the side to which the line fades. (you sometimes have to search hard to find these blue lines on a sectional. They are usually found in remote areas and fade toward the more populated areas of the chart; eg you might find one over the ocean fading towards the land, over a mountainous area fading toward flatter terrain, etc. They look just like the far more common "magenta" faded lines, only they're blue). The VAST majority of the area of most sectionals I've seen IS on the faded side of one of these blue lines, but you still have to see one of these blue lines to be sure that class E begins at 1200 AGL.

A fading magenta line on a sectional indicates that class E begins at 700 ft AGL on the side to which the line fades.

A dashed magenta line indicates that class E extends to the surface.

Class G cannot exist above 14,499 MSL unless terrain extends above this altitude, in which case Class G extends from the surface to 1,499 AGL with class E above that.

An "uneven" solid blue line is used to specify intermediate altitudes for the floor of Class E between 1,200 AGL and 14,500 MSL.

It's a complicated subject to explain without diagrams and actual sectionals to provide example from....looking at a diagram in a jeppesen book would probably be far more helpful than anything I could muster.....

Anyone feel free to correct anything I may have messed up
So if Class A ends at FL 600 (which it does), what is the airspace above FL 600 designated?

Best one I heard was a U-2 that got the clearance "Dragon 21, leaving FL 600, departing Class A airspace, squawk VFR or appropriate code, frequency change approved, good day."
It's class G above FL 600 I think?

Just to clear up one thing about my blue line 14,500 MSL is partially ambiguous to describe 14,500 MSL as the "standard" height of class G because the sectional itself says in the key "assume class E starts at 1200 AGL unless otherwise inidcated", and like I said the vast majority of the area on most sectionals does have class E starting at 1,200 AGL.

However, for some reason I find it easier to explain 1,200 as being a step down than saying 14,500 is a step up because of the way the faded line is depicted on the sectional. All you really need to know is that if you see a faded blue line, class E starts at 1,200 AGL on one side and "some other higher altitude (usually 14.5)" on the other.