Question about Non-Standard Class E Floors

[eetrojan]

Hey all, Hope this isn't a dumb question, but I have been studying airspace and, for the life of me, cannot figure out "why" the FAA is differentiating Class E floors beyond the normal 1200 AGL, 700 AGL extensions, or surface area extensions. I'm talking about the Class E floors that are "differentiated" with the staggered blue bars.

Here's an example of a Class E floor that I found in the California desert. As I understand it, this means the floor is at 10,500 MSL rather than 1200, which also means that the Class G space rises upward to 10,499 in this same area:

So, to help me understand, why would they designate such a variation?


Also, my memory nmemonics are

• A for Alpha dog
• B for Big
• C for Crowed
• D for ????
• E for Everywhere with lots of Exceptions, and
• G for Ground

Anybody got a good one-word memory aid for Class D?

Thanks!

Joe

 

[Palmpilot]

I don't know about the example chart that you posted, but some places don't have radar coverage down to 1200 AGL. I don't know if that's the only reason.

 

[Jim Logajan]

Hey all, Hope this isn't a dumb question, but I have been studying airspace and, for the life of me, cannot figure out "why" the FAA is differentiating Class E floors beyond the normal 1200 AGL, 700 AGL extensions, or surface area extensions. I'm talking about the Class E floors that are "differentiated" with the staggered blue bars.

Here's an example of a Class E floor that I found in the California desert. As I understand it, this means the floor is at 10,500 MSL rather than 1200, which also means that the Class G space rises upward to 10,499 in this same area:

So, to help me understand, why would they designate such a variation?

Actually the floor of Class E normally begins at 14,500 ft MSL, not 1200 ft AGL. As I understand it, it just happens that vast areas of the U.S. are designated as en route domestic areas for the purposes of ATC, so Class E is dropped to 1200 AGL. See also:

http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0302.html

 

[eetrojan]

Thanks guys. I completely missed the part about the nominal floor for Class E being at 14,500 MSL. I will read that link carefully. Appreciate it. Joe

 

[eetrojan]

Actually the floor of Class E normally begins at 14,500 ft MSL, not 1200 ft AGL. As I understand it, it just happens that vast areas of the U.S. are designated as en route domestic areas for the purposes of ATC, so Class E is dropped to 1200 AGL. See also:

http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0302.html

OK, let me see if I get this. Here's an excerpt of the more crowded air space around my neck of the woods. I understand that the part that I lightened inside of the faded magenta border is Class E with a floor at 700 AGL.

How about the areas I left dark? Is that Class E with a floor of 1200 AGL (what I thought until now), or with a floor of 14,500 MSL?

Thanks!

 

[Sam D]

Check out the legend to the sectional. It notes that:

Class E Airspace exists at 1200' AGL unless otherwise designated as shown above.

As for your earlier nmemonics question. I'd say don't sweat it. When you're ready for your checkride, these will be well drilled into you. When all else fails, just think of it as most to least busy alphabetically (A is kind of an exception).

One more thing, the test supplment for the private written has the legend in it. It's a good cheat sheet for the written.

 

[Jim Logajan]

OK, let me see if I get this. Here's an excerpt of the more crowded air space around my neck of the woods. I understand that the part that I lightened inside of the faded magenta border is Class E with a floor at 700 AGL.

How about the areas I left dark? Is that Class E with a floor of 1200 AGL (what I thought until now), or with a floor of 14,500 MSL?

Thanks!

Sam D. has already answered that question; the default floor for the sectional is on its legend (1200 ft AGL.) I should point out that the only reason I brought up the less well known 14,500 ft MSL floor is because I got asked a question about this subject during my oral exam
[*].

The sectional for the area I fly in is the Klamath Falls one. The floor of Class E is all over the map on that sectional in more ways than one.

(Trivia) questions for you or anyone else who wants to give it a shot:
What is the ceiling of Class G above the following airports (all on the Klamath Falls sectional):

Ravendale California (o39)?
Adin California (A26)?
Spaulding California (1Q2)?
Southard California (o55)?
Observation Peak, a mountain about 9 miles east of Ravendale?


[*] I believe we were looking at the Seattle Sectional at the time and the DPE pointed to, if I recall correctly, somewhere near Lost River Washington (W12). In the northwest of its overlying airspace where its boundary runs into the Canadian border is where the floor of Class E is written for the adjacent airspace: 1200 AGL. Try as you might (unless I and the DPE missed it) there is no mention of the floor for Class E for the airspace that lies over W12. So it has to be different than 1200 AGL. I tried to locate the "default" in the AIM and vaguely remembered it being some large number but couldn't find it. The DPE eventually found it for me, but it took him a few minutes of searching to locate it.

 

[Jeanie]

D for dialogue?

 

[kkoran]

I don't know about the example chart that you posted, but some places don't have radar coverage down to 1200 AGL. I don't know if that's the only reason.

Radar coverage has nothing to do with the designation of Class E airspace.

 

[kkoran]

So, to help me understand, why would they designate such a variation?

Short answer: Because the airspace in the designated area does not meet the criteria for Class E airspace below 10,200 MSL.

 

[Palmpilot]

Short answer: Because the airspace in the designated area does not meet the criteria for Class E airspace below 10,200 MSL.

The needle he's looking for is in that haystack over there! :wink2: