Class E?

popaviator

popaviator

Well-Known Member
A student asked me the best way to understand class E airspace. He asked if it's controlled then why don't we have to talk to anyone. So I explained that one of purposes is to keep VFR traffic away from IFR traffic. It's also easier to get ATC services in E. Anything else I'm missing? or any input you guys can give me? :pirate:
 
popaviator said:
A student asked me the best way to understand class E airspace. He asked if it's controlled then why don't we have to talk to anyone. So I explained that one of purposes is to keep VFR traffic away from IFR traffic. It's also easier to get ATC services in E. Anything else I'm missing? or any input you guys can give me? :pirate:
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VFR cloud clearances and viz are tighter. Controlled doesn't necessarily mean with an ATC controller, as you already know. It can mean tighter regulations, hence controlled.
 
popaviator said:
A student asked me the best way to understand class E airspace. He asked if it's controlled then why don't we have to talk to anyone. So I explained that one of purposes is to keep VFR traffic away from IFR traffic. It's also easier to get ATC services in E. Anything else I'm missing? or any input you guys can give me? :pirate:
Click to expand...

It is controlled for the purposes of handling IFR traffic. It basically is an "if your not above this height there is no way we will reach you on radar to provide you services."

It is the airspace where you can be in contact with ATC and use their services if you wish, but you do not have to. Obviously when you move the the IFR level then that airspace is there to show us when we can expect to start talking to ATC for our flight.

Radar is LOS, that is the main reason per my understanding. Just to note though this was only hear say from teachers, I do not have verified sources for you.


Edit: I would definitely mention the tighter regulations too as Mike said with the second paragraph I have and I think you will cover everything a VFR pilot needs to know for that airspace. Something like, Class E has tighter regulations than G and is airspace where you have the option to utilize radar services but are not required to.
 
MikeD said:
It can mean tighter regulations, hence controlled.
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Controlled airspace requires some form of ATC control, by definition. From 14 CFR 1.1:

Controlled airspace means an airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification.
​
 
tgrayson said:
Controlled airspace requires some form of ATC control, by definition. From 14 CFR 1.1:

Controlled airspace means an airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification.
​
Click to expand...

You're not meaning that one has to be talking to ATC when in Class E or receiving any form of clearance to enter?
 
MikeD said:
You're not meaning that one has to be talking to ATC when in Class E or receiving any form of clearance to enter?
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No it wouldn't because of this, "in accordance with the airspace classification." That part in quotes directs you to each individual airspace regulation to find out if you are required to or not.
 
MikeD said:
You're not meaning that one has to be talking to ATC when in Class E or receiving any form of clearance to enter?
Click to expand...

Controlled airspace...air traffic control service is provided... to VFR flights in accordance with the airspace classification.

Class E does not require communication with VFR flights, and therefore ATC services are being provided in accordance with the airspace classification. ATC services, however, may be provided to VFR aircraft if VFR aircraft request them.
 
tgrayson said:
Controlled airspace...air traffic control service is provided... to VFR flights in accordance with the airspace classification.

Class E does not require communication with VFR flights, and therefore ATC services are being provided in accordance with the airspace classification. ATC services, however, may be provided to VFR aircraft if VFR aircraft request them.
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OK, thats what I thought you were meaning, and what I was telling the OP....he had the ATC portion seemingly covered, but didn't mention the tighter cloud clearances, which is why I threw out the regulatory portion of the subject. Pretty well covered all around now! :)
 
Continuing on...does anyone know the reason for 1,000' above, 500' below and 2,000' horizontally for VFR cloud clearance in controlled airspace? One might argue that the bases tend to be more regular/even than tops, but I don't think that it the primary reason for this.
 
Aircraft climb faster than they descend (except the light piston ;) ) and they can turn and come out of a cloud very quickly as well.

RD
 
I was always under the assumption that it was because clouds developed vertically from the top. I've never seen a cloud develop from the base. To me, the flat bottom looks like a distinct visual representation of the thermocline between the temp above dewpoint and the temp at and below dewpoint.
 
OhioStatePilot said:
I was always under the assumption that it was because clouds developed vertically from the top. I've never seen a cloud develop from the base. To me, the flat bottom looks like a distinct visual representation of the thermocline between the temp above dewpoint and the temp at and below dewpoint.
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:yeahthat: This is what I was taught too though honestly the reason doesn't matter and IMO these requirements don't seem to make sense to me when applied to traffic avoidance. For instance, 2000 feet at 300 knots takes about 6 seconds, assuming 200 from a jet and 100 from a typical piston. The point is with out some real good luck if your on a collision course when the person pops out of the clouds the chances of you looking exactly in the right spot or scanning that spot within 6 seconds is likely slim to none.

It would seem to me that given that, putting this up for the purposes of traffic avoidance doesn't seem logical or practical, at least not given 6 seconds in the above example. I would assume and it would make more sense to me that each clearance is given based on the likely hood of being swallowed by the clouds. Horizontal being the quickest form of development, then vertical, and finally descending.

Clouds develop in any direction the airflow and moisture allows, you certainly can have clouds that build out from the base if there is circular flow inside the cloud is pushing air and moisture down. For proof, fly just under a level of clouds and notice how some parts hang lower than others.
 
Even 500 below may or may not be enough. Hard to judge, and no guarantee (are there ever any?) of a good chance for collision avoidance.

Case in point was the KC-135 that descended out of the WX on a TACAN 3L final segment, and collided with a Grumman AA-1 that was just below the cloud deck in cruise, all fatal. The AA-1 was closer than 500 feet it was imagined, but still there was little time for avoidance, and the -135 crew never saw him. Kind of a fluke accident, but some good lessons learned particularly with what may or may not work with some current regs.
 
OhioStatePilot said:
I was always under the assumption that it was because clouds developed vertically from the top. I've never seen a cloud develop from the base. To me, the flat bottom looks like a distinct visual representation of the thermocline between the temp above dewpoint and the temp at and below dewpoint.
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This can also be used to predict a front moving in from looking at contrails. The longer the contrails stay in the air the better chance of rain within a few days. The less time they spend in the sky the more likely good weather is and will stay. :)
 
splash said:
This can also be used to predict a front moving in from looking at contrails. The longer the contrails stay in the air the better chance of rain within a few days. The less time they spend in the sky the more likely good weather is and will stay. :)
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Haha I am surprised anyone even remembers that. It is a great way for planning a day at the beach a couple days in advance though!
 
shdw said:
It is controlled for the purposes of handling IFR traffic. It basically is an "if your not above this height there is no way we will reach you on radar to provide you services."

It is the airspace where you can be in contact with ATC and use their services if you wish, but you do not have to. Obviously when you move the the IFR level then that airspace is there to show us when we can expect to start talking to ATC for our flight.
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I would disagree with you on the wording here shdw. A guy who doesn't already know the answer would take the words and run the wrong way.
Words like "radar" and "ability to use ATC services or "expect to start talking to ATC".

i.e. I was cruising over Iowa today at 4000 feet, 3000 feet AGL and class E started at 1200 feet agl in that area and I was not in Radar contact but using there services. Radar coverage has nothing to do with class E.

or

shoot an approach in to http://skyvector.com/?icao=spw&metars=on
kspw. They have Class E to the surface, they will not be able to see you below 3000 feet in that area but they can still clear you for the approach.
Why is it there then? It is only there to keep VFR pilots that know better out of that area if they don't want to break regs while they are scud running in reduced weather minimums. It is a see and avoid world, even when you are IFR.
So really ATC is not protecting you in the E, your faith in your fellow GA scud runner desire to not break regs is!

Also, IFR into G is allowed, and communication with ATC is not guaranteed inside or out side of E.

All this stuff you know, but the wording like that puts the ball in the students courts to run-a-muck with your meaning.
 
Douglas said:
i.e. I was cruising over Iowa today at 4000 feet, 3000 feet AGL and class E started at 1200 feet agl in that area and I was not in Radar contact but using there services. Radar coverage has nothing to do with class E.
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I was claiming in class G there was absolutely no way to get radar and that is it. But I see what you mean that a student could take that to assume anytime out of class G you can get radar, which as you pointed out isn't the case. Nice catch man! Thanks.

With that your addition here I would add in "In class E airspace you can use ATC services which may or may not include radar services depending on the area" or something to that effect. Would that fix up any issues that you can see Douglas?

Edit: Oh boy I just saw what you meant with the IFR aspect as well...woops
 
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