Question on Sectionals

[Huggyu2]

Sectionals have magenta areas (one edge is "hard" and the other "soft") that delineate where the floor of controlled airspace goes from 1200 AGL to 700 AGL. Who uses/needs this info? Are there really that many pilots that need that info?
It's not something I've ever found I need to know while navigating around, but I'm sure it's beneficial to someone. Can you give me an example of how you would use this info to your benefit?

 

[CA1900]

Sure: You're in a Skyhawk, cruising at 1,000 feet, beneath a 1200-foot overcast layer. Perfectly legal -- you're in Class G airspace. But not once you get to the shaded magenta area, because above 700 feet you're now in Class E, and need 500 feet below the clouds. You'll have to go around it, or go lower if terrain permits.

The short answer is that it's to keep VFR traffic out of the instrument approach corridors on crappy days. (You'll notice these areas are over nontowered airports, typically. Note that some of them are kind of "keyhole"-shaped, to correspond with the final approach courses.)

 

[mattpilot]

It has to do with the difference of cloud clearence/visibility requirement.

The Class E drop down to 700ft AGL protects the airspace for IFR flyers from low flying Class G flyers who use the reduced requirements to "scud run" - in theory. In practice, i don't really know anyone who is crazy enough to go flying in such poor conditions that low anyway. Although it is fun... wait.. did i just say that?

 

[FN FAL]

Sectionals have magenta areas (one edge is "hard" and the other "soft") that delineate where the floor of controlled airspace goes from 1200 AGL to 700 AGL. Who uses/needs this info? Are there really that many pilots that need that info?

It's not something I've ever found I need to know while navigating around, but I'm sure it's beneficial to someone. Can you give me an example of how you would use this info to your benefit?

You need to know where controlled airpace begins in the event that you are flying on instruments outside of controlled airspace, so that you will know where you are not authorized to be.

 

[MauleSkinner]

It has to do with the difference of cloud clearence/visibility requirement.

The Class E drop down to 700ft AGL protects the airspace for IFR flyers from low flying Class G flyers who use the reduced requirements to "scud run" - in theory. In practice, i don't really know anyone who is crazy enough to go flying in such poor conditions that low anyway. Although it is fun... wait.. did i just say that?

Hi Matt, my name is David. You now know somebody who is "crazy enough" to go flying at 600-700 feet all day long. It's safe enough if you're willing to put in the effort to navigate properly and keep your eyes open for uncharted towers and traffic.

As to Huggyu2's orignal question, yes, that's the primary reason...VFR visibility and cloud clearance requirements change when you get into controlled airspace, and you need to know where those airspace changes are in order to be legal AND to ensure that you're properly separated from IFR traffic. Remember, too, that instrument approaches usually take you below 700 feet AGL, so IFR traffic can be in the underlying uncontrolled airspace as well...use caution.

No, I don't recommend flying down there to just everybody...as I stated earlier, it takes substantial extra effort to maintain the level of safety. You can't just hit "direct to" on the GPS and turn on the autopilot.

Fly safe!

David

 

[mattpilot]

Hi Matt, my name is David. You now know somebody who is "crazy enough" to go flying at 600-700 feet all day long. It's safe enough if you're willing to put in the effort to navigate properly and keep your eyes open for uncharted towers and traffic.

Hi david. I was trying to be subtle in my last sentence - the one with the smiley.

 

[MauleSkinner]

Hi david. I was trying to be subtle in my last sentence - the one with the smiley.

Subtlety is lost on me...I'm a "blunt instrument" kind of guy

 

[NW_Pilot]

It has to do with the difference of cloud clearence/visibility requirement.

The Class E drop down to 700ft AGL protects the airspace for IFR flyers from low flying Class G flyers who use the reduced requirements to "scud run" - in theory. In practice, i don't really know anyone who is crazy enough to go flying in such poor conditions that low anyway. Although it is fun... wait.. did i just say that?

Hey, matttpilot I am NW_Pilot Nice to meet ya! Now you know another that is that crazy! and Yea it's a blast!

 

[heph224]

Sectionals have magenta areas (one edge is "hard" and the other "soft") that delineate where the floor of controlled airspace goes from 1200 AGL to 700 AGL. Who uses/needs this info? Are there really that many pilots that need that info?
It's not something I've ever found I need to know while navigating around, but I'm sure it's beneficial to someone. Can you give me an example of how you would use this info to your benefit?

As you can see, the class E drops to 700 around airports. Think about it, if the airport elevation is 0 MSL, and you are flying a TP at 1000 MSL and it's an uncontrolled field (no communication is required) what if someone is on a right downwind for runway 9 and another person is on a left downwind for runway 27 and there is small cloud on the downwind leg which both pilots navigate around ( class G 1sm COC ). This can cause a very dangerous environment especially with low vis and uncontrolled airports. Therefore, the magenta lines drops the floor of class E to 700 in order for airplanes converging in the TP and around the airport to have higher vis and coc mins.

This is also for IFR purposes, IFR pilots need to know and prefer to get into controlled airspace ASAP after departure, especially when getting a clearance from an RCO or such.

 

[Huggyu2]

Great! I thought there might be more to it than I was missing.
Next set of questions: since this is purely to allow pilots to get different VFR WX mins:
- do that many pilots really fly around a bare VFR mins, below 1200' AGL? I see that at least one on this forum does, but are there really enough to warrant all of this?
- If the WX is low enough that you need to duck down below 1200' AGL or even 700' AGL to navigate around the country on a regular basis, why wouldn't you just go above it, or file IFR (yes, I know it's a lot of fun).
- I know none of you wrote the rules (you just abide by them), but maybe you CFI/CFII types have some background knowledge on this: why not just have the floor be a compromise of about 1000' AGL, and be done with this 700'/1200' complexity? Does having a single altitude really adversely affect a bunch of flyers (crop dusters maybe)?
- Is it just me, or do others find having so much magenta all over the sectionals make the sectionals cluttered? I know I'd sure like it if I could buy Sectionals that didn't have all of that on them.

Don't think I don't like flying low. I just don't see a big reason to have two different altitudes when one compromise altitude (1000') would seem to work for everyone. Educate me, folks!