Class G Vert Limits

[seattle]

What FAR tells me that class G is terminated at either 14500' MSL (class E) or 1500' AGL which ever is higher - unless otherwise specifically noted.

Ref the Jeppesen cross-sectional view of the airspace system to see what I'm talking about.

Thanks.

Seattle

 

[Five-O Pilot]

Seattle,

I found this for you in the 14 CFR Part 71:

"§71.1 Applicability.


The complete listing for all Class A, Class B, Class C, Class D, and Class E airspace areas and for all reporting points can be found in FAA Order 7400.9J, Airspace Designations and Reporting Points, dated August 31, 2001. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. "

But I'll be d***ed if I can find FAA Order 7400.9J anywhere! I found the above info at

http://www.access.gpo.gov/nara/cfr/cfrhtml_00/Title_14/14cfr71_00.html

Sorry I couldn't be of more help.

5-O

 

[cvsfly]

Class G (U.S. Airspace) by definition (FAR 71 and AIM) is considered everything not otherwise labeled Class a,b,c,d, or e. Generally speaking in continental U.S. Class E base is at 1200 agl or 700 agl (transition area for IAP at an airport - magenta on VFR sectional) unless designated otherwise (some mountainous areas that are >1200' agl). Class G is below this.

 

[172driver]

"Generally speaking in continental U.S. Class E base is at 1200 agl or 700 agl (transition area for IAP at an airport - magenta on VFR sectional) unless designated otherwise (some mountainous areas that are >1200' agl). Class G is below this."

cvsfly,

Are you telling us that there is generally no Class G airspace between 1200' AGL and 14,500 MSL? Take a look at a Los Angeles sectional and tell me where Class E airspace begins when not designated on the chart. That's right...14, 500 MSL.

If the Class E base was generally at 1200' AGL, why does the chart legend have that funny blue shading that brings Class E to 1200' AGL?

This is a misconception many of my students have as well. None have flown in the western half of our country where the chart doesn't have that note on it bringing all Class E to 1200' AGL. Many pilots think Class E airspace always starts at 1200' unless otherwise designated. They wouldn't know what to think if they saw blue shading around an airport.

 

[FlyinBrian]

I think the misconception is because John King or some other aviation lame-o uses G=ground as a nmemonic for where class G exists.

The best definition for the veritcal limit of class G is the floor of the overlying airspace, which is 14,500 in the absence of any other marked airspace.

 

[cvsfly]

Thats why I said --- "unless designated otherwise (some mountainous areas that are >1200' agl)". and offshore, etc. Read your charts. They usually have all the answers concerning airspace dimensions.

 

[172driver]

OK...how is the Class E "designated" on the L.A. chart? Yes, mountainous areas are sometimes zipper lined to provide a Class E floor but this is not the case in my example. There is no designation on the chart or in the legend of where Class E starts so...it starts at 14, 500' MSL. It is actually the lack of a designation which tells us this.

 

[seattle]

Isn't there a note in the chart legend that says

"CLASS E AIRSPACE EXISTS AT 1200' AGL UNLESS OTHERWISE DESIGNATED AS SHOWN ABOVE"

What becomes a bit confusing is that the Jeppesen cross-sectional view of the airspace system shows E begining at 1500' AGL - but that's only above 14500' MSL, isn't it? The words for this can be found in FAR 71.71(a2). It doesn't seem like there would be much real estate within the USA that would be affected by this provision. Just my .02

Seattle

 

[cvsfly]

Referencing a "VFR" Sectional chart. I don't have one infront of me and maybe I haven't looked at one closely lately. The base of class E is designated at 700agl around airports that typically have only unicom services and an IAP (i.e. no TWR, CZ) this allows Instrument approaches to be contained in "controlled" airspace a little longer - think VFR weather minimums. These typically look like a key hole with magenta shading. The blue shading on the outside of this area designates class E at 1200 agl. Offshore areas have a symbol like _--_-- _ in blue with [25] designating the altitude = 2500'msl (the symbol is kind of hard to replicate here) and mountanious areas typically >14,500 msl & >1500' agl have segments of airspace outlining airways (what is it 4 or 5 nm clearance from centerline?) Oh, by the way is LA Lower Alabama?

 

[Timebuilder]

While I don't have a western US chart here, the floor of class E, where G ends out west, does not have a chart designation symbol, other than when it is less than 14,500, using the blue vignette, as stated above.

I am told that the 14,500 level was chosen because of the highest point in the continental US, and to allow for uncontrolled airspace over the US when controlled airspace is not necessary.

I make a point (ahem, MADE a point..) of teaching all of my students about the difference between eastern and western US airspace and chart symbology. I found it helps them to "see" a victor airway, for example. A close study of the two page Jepp diagram should make the subject clear, along with the description in the FAR/AIM.

 

[172driver]

Isn't there a note in the chart legend that says

"CLASS E AIRSPACE EXISTS AT 1200' AGL UNLESS OTHERWISE DESIGNATED AS SHOWN ABOVE"


Seattle,

No there isn't. That was my point. Everyone assumes that the note is there on all sectionals but it is not! So, again, Class E begins at 14, 500' MSL on this chart unless otherwise designated.

 

[cvsfly]

Couple of my bads. I meant to say on the scectional chart base of class E is usually designated, when it is other than 1200 agl, when it is > 1500agl and < 14,500 msl and not > 14,500.
Also the [25] symbol is wrong. It will say 2500 agl or msl.

172driver said:
-------------
" "Isn't there a note in the chart legend that says

"CLASS E AIRSPACE EXISTS AT 1200' AGL UNLESS OTHERWISE DESIGNATED AS SHOWN ABOVE" "


Seattle,

No there isn't. That was my point. Everyone assumes that the note is there on all sectionals but it is not! So, again, Class E begins at 14, 500' MSL on this chart unless otherwise designated."

-------
Yes there is. I got my LA lala chart here. Look off shore from LA towards San Nicolas Island. Bunch of control areas NW of there. In shore of that blue --_--_ line (overlapping kind of like a zipper) designates base of class E at 1200 agl (number not depicted = assumed) - outside of the line you see "5500 msl". That is base of class E there. In-land a good example is on the Las Vegas sectional north side west of Wilson Creek VOR - ILC. V244 is "outlined" with the blue zipper line with 11,500msl inside. That is the base of class E. To the North of V244 is also a notation for "11,500 msl / 14,500 msl ceiling" meaning that Class E base at 11,500 and ceiling at 14,500 -- actually this is a 1994 chart so the term "continental control area" (at 14,500) was in use but still illustrates the point. The Chart legend has all of this under "Airport traffic service and Airspace Information" - "2400 msl --_--_ 4500 msl Differentiates floors of class E greater than 700 agl. Class E airspace exists at 1200 agl unless otherwise designated as shown above". And why do we care about all of this? Mostly because of VFR weather minimums and other requirements/restrictions of certain operators (135/121) to be operating in class G. Hope this helps.

 

[cvsfly]

I reread your post 172driver and it occured to me that we maybe missing your point. You would be right to say "Class E starts at 14,500 unless otherwise designated". There are very few places (I can't recall any and I don't have the time to look) where that would be the case. Your sectional chart is full of areas where Class E is designated as indicated in my above post.

 

[172driver]

cvsfly,

Does your Los Angeles sectional say in the legend, "Class E airspace exists at 1200' AGL unless otherwise designated as shown above" ? Mine doesn't but is a couple yrs old.

I understand how to read the zipper lines and shadings. My point was: if there are no zipper lines, victor airways, shadings on the chart, Class E begins at 14, 500' MSL. This is not true on most sectionals because of the note in the legend bringing the floor of E down to 1200' AGL (Domestic enroute airspace). My L.A. chart does not have this note. Can we agree that Class E begins at 14, 500' MSL if not designated on the chart by other symbols?

 

[cvsfly]

Sorry, can't agree. If your LA chart doesn't have that notation, it is probably a miss print. The notation and symbology for the airspace should still be there. It would not be quite as colourful if it wasn't. The only areas on the LA sectional where Class E would start at 14,500 would be near the highest mountain peaks close to 13,000' (i.e. 1500 agl). You should be able to follow the blue shading (I know - kind of hard with all of the other colors) or see the blue "zipper" line.

 

[172driver]

OK, so your chart has that notation in the legend? I see the blue shading over most of the chart and the zipper lines but...in areas not shaded, zippered, dashed, etc...where does E start? Is it 1200' AGL or 14, 500'MSL? Most sectionals have the notation in the legend bringing ALL E down to 1200' but my LA chart doesn't have it. Does yours specifically say Class E airspace exists at 1200' AGL unless otherwise designated as shown above?

 

[cvsfly]

Yes.