Question re Flight Following Through Charlie Shelves

[eetrojan]

I have a question re flight following and Charlie shelves. I made the diagram of my local area to provide some context.

I train out of a Class C airport called John Wayne (SNA), which is near Ontario (ONT), another Charlie. As you can see, there are several delta airports that are underneath the 2700 ft. floor of ONT’s shelf, including Riverside (RAL), Chino (CNO), and Brackett (POC).

When we fly the green course northeast from SNA to CNO without flight following (i.e. without talking to SoCal Approach, our local TRACON), we fly at 3,000 ft., call CNO tower, and then descend below ONT’s shelf by dropping down to 2500 feet before we get there, at around “A.” That makes sense.

I am trying to understand what I must or can do, however, if I was getting traffic advisories from SoCal Approach.

As I understood him, my instructor tells me that IF I was flying the red course eastbound to RAL, at 4000 ft. and while receiving traffic advisories from SoCal approach, I could fly through the Charlie shelf as shown by the red line below and then, after SoCal tells me to contact RAL tower at “B,” I could continue flying in the Charlie even though I am no longer communicating with SoCal (be kind of hard to do otherwise, of course), contact RAL tower and, once radio contact is made with RAL tower, descend down from the Charlie into RAL’s delta.

So, that’s my basis for this question:

Assuming that I’m flying the blue course northbound from SNA to POC at 3,500 ft. and while on flight following with SoCal, and assuming that SoCal tells me to contact POC tower at “C,” can I without busting airspace fly through the edge of the Charlie on my way down to POC’s delta? ...or MUST I duck under the Charlie like the green course because I was handed off to tower, am not communicating with SoCal, and am not currently in the Charlie?

Would the answer be different if I was already in the ONT Charlie when SoCal told me to contact POC tower, so that the blue course situation were more clearly like the red course situation?

Thanks!

 

[CaptLabrador]

From how I understand it. If you are talking to so cal and they know your destination either they will hand you off to poc or if its necessary ont. most likely they will be in communication with ont and ont will know you are there even if you are handed to poc. So it will be a non issue.

 

[poadeleted20]

As long as you are talking to whatever ATC facility ATC directs you to contact (and Towers are ATC facilities), you're fine. If SoCal tells you to switch to Brackett Tower, you can continue on your course. If there's a need to switch back to SoCal later, it's then Brackett's responsibility to send you back.

 

[MAKG1]

Class B and Class C transitions are usually handled by Approach (SoCal), except for low altitudes in the surface area. That's the point of the magenta boxes telling you to contact them. And they will hand you off if it's weird over there.

You may get vectored, especially if you cross an extended centerline. More likely, you'll get asked intentions. Not a big deal. It's usually easiest to cross a conga line directly over midfield at a few thousand feet AGL.

When I approach PAO from the south, I usually pass through a Class C and a neighboring Class D to do it. The handoffs occur a little earlier than you might expect, due to local letters of agreement. Follow instructions and you're good to go.

 

[rbridges]

As long as you are talking to whatever ATC facility ATC directs you to contact (and Towers are ATC facilities), you're fine. If SoCal tells you to switch to Brackett Tower, you can continue on your course. If there's a need to switch back to SoCal later, it's then Brackett's responsibility to send you back.

I was going to say the same thing. ATC should direct your calls.

 

[eetrojan]

Thank you!

Just to make sure I get it, this is what I think I’m hearing.

If I’m flying the blue course from SNA to Brackett while talking with SoCal (an ATC facility), and they direct me to call Brackett Tower (an ATC facility), then I can proceed to Brackett without any concern whatsoever of busting ONT’s Charlie shelf because that’s an expected part of my vector, SoCal will make ONT aware of me, etc.

But, if I was flying the blue course without talking to ATC and I independently called Brackett Tower before I entered their airspace, say about 8 nm out, I better make darn sure that I dip below the ONT shelf.

Sound like I’m on the right page?

 

[eetrojan]

From how I understand it. If you are talking to so cal and they know your destination either they will hand you off to poc or if its necessary ont. most likely they will be in communication with ont and ont will know you are there even if you are handed to poc. So it will be a non issue.

Thanks Adam. I just flew this route as part of my stage check and they handed me off to POC after I asked for a temporary frequency change to get the ATIS, but because of my inexperience and concern about airspace, I made an affirmative effort to descend and stay below ONT's shelf.

It sounds like I did NOT need to do that given what you and other folks are telling me.

Appreciate it.

 

[eetrojan]

Class B and Class C transitions are usually handled by Approach (SoCal), except for low altitudes in the surface area. That's the point of the magenta boxes telling you to contact them. And they will hand you off if it's weird over there.

You may get vectored, especially if you cross an extended centerline. More likely, you'll get asked intentions. Not a big deal. It's usually easiest to cross a conga line directly over midfield at a few thousand feet AGL.

When I approach PAO from the south, I usually pass through a Class C and a neighboring Class D to do it. The handoffs occur a little earlier than you might expect, due to local letters of agreement. Follow instructions and you're good to go.

I just looked up KPAO. Wow. That's some crazy looking airspace given the vertical stacking of the intersecting deltas, the SJC and OAK charlies, and the SFO bravo. Yikes.

 

[MAKG1]

I just looked up KPAO. Wow. That's some crazy looking airspace given the vertical stacking of the intersecting deltas, the SJC and OAK charlies, and the SFO bravo. Yikes.

Except the Class C and D airspaces are near nonevents with flight following. Class B is generally quite cooperative as well (even an hour after the Asiana crash), but there is more to that.

You just don't expect to fly over the bay at 4000 feet. Under 1500 is fine over most of it. The floor is higher further south.

The worst we hear is an instruction to fly a base entry below 1500 from PAO tower, or maybe to stay within 2 miles in the pattern on the rare day extensions into Moffett aren't authorized.

 

[CaptLabrador]

Thanks Adam. I just flew this route as part of my stage check and they handed me off to POC after I asked for a temporary frequency change to get the ATIS, but because of my inexperience and concern about airspace, I made an affirmative effort to descend and stay below ONT's shelf.

It sounds like I did NOT need to do that given what you and other folks are telling me.

Appreciate it.

You sir are very welcome. Also, ATC is not out to bust you just to help so if you are ever in doubt it never hurts to ask.

 

[poadeleted20]

Thank you!

Just to make sure I get it, this is what I think I’m hearing.

If I’m flying the blue course from SNA to Brackett while talking with SoCal (an ATC facility), and they direct me to call Brackett Tower (an ATC facility), then I can proceed to Brackett without any concern whatsoever of busting ONT’s Charlie shelf because that’s an expected part of my vector, SoCal will make ONT aware of me, etc.

But, if I was flying the blue course without talking to ATC and I independently called Brackett Tower before I entered their airspace, say about 8 nm out, I better make darn sure that I dip below the ONT shelf.

Sound like I’m on the right page?

If you're below 2700 as you hit the D-space boundary, then you're in Brackett Tower's airspace, and SoCal should either hand you to Brackett Tower or coordinate your transit with Tower while retaining you on their freq. If you're above 2700, you're above Brackett Tower's airspace, and SoCal should not hand you to Brackett Tower, but retain you on their freq. What you cannot do is get handed to Brackett Tower in their D-space (i.e., below 2700) and then climb above 2700 into the overlying C-space that Tower doesn't own without coordination between Tower and SoCal or a handoff to SoCal, or be above 2700 with SoCal and descend to below 2700 into Brackett's airspace without SoCal coordinating with or handing you to Tower.

 

[eetrojan]

1. If you're below 2700 as you hit the D-space boundary, then you're in Brackett Tower's airspace, and SoCal should either hand you to Brackett Tower or coordinate your transit with Tower while retaining you on their freq.
2. If you're above 2700, you're above Brackett Tower's airspace, and SoCal should not hand you to Brackett Tower, but retain you on their freq.
3. What you cannot do is
   • get handed to Brackett Tower in their D-space (i.e., below 2700) and then climb above 2700 into the overlying C-space that Tower doesn't own without coordination between Tower and SoCal or a handoff to SoCal, or
   • be above 2700 with SoCal and descend to below 2700 into Brackett's airspace without SoCal coordinating with or handing you to Tower.

Thanks Ron. But for my better understanding, are you explaining how things should go if I was transitioning through Bracket’s D-space, as opposed to landing at Brackett? That's what it seems to me, but I'm not sure.

When I flew the blue route, I departed SNA after informing John Wayne Clearance that I wanted an “Orange” departure (330 magnetic heading when departing from SNA) to Brackett, and it appeared that SoCal knew I intended to land at Brackett. When I asked for a temporary frequency change to check the ATIS, while I was at 3500 feet and about 12 nm out, they approved my request and directed me to call Brackett tower after I got the ATIS.

Also, as another data point, I was able to connect with my instructor a bit on this same question. He tells me that since I was with SoCal, I didn’t need to dive beneath the ONT Charlie on my way down to Brackett, but I definitely should not “loiter” in the Charlie on my way in. In other words, if I want to circle over Bracket to familiarize myself, I should request 2500 from Brackett and circle within their D-space, and not assume that I have carte blanche to circle around above their D-space, say at 3000, within the Charlie.

Thanks for your help.

 

[poadeleted20]

Thanks Ron. But for my better understanding, are you explaining how things should go if I was transitioning through Bracket’s D-space, as opposed to landing at Brackett?

Yes -- I thought that was the question. If you're landing at Brackett with flight following from SoCal, you just do whatever they tell you and switch to tower when instructed.

 

[MAKG1]

There is nothing wrong with loitering in Class C. Some folks like to do airwork southwest of SJC. A local examiner has even expressed a desire to give checkrides there, though I'm not aware of anyone actually doing that. There is surprisingly little traffic there. Just tell Approach what you want to do. They may say no if you're in a bad place such as near an instrument approach or departure (the most commonly used southbound DP is why you won't get away with this northeast of SJC).

Once you've done this a few times, you'll learn that the point of Class C is to force you to talk to ATC, and not a whole lot else. It's really not a big deal. The key is advising your intentions. When I transition SJC, I know the controller's big concern is how I interact with the extended centerlines, so I'll usually volunteer that. "NorCal Cessna 123XY at 1500 request midfield transition at 3500"

You can even loiter in Class B once cleared (as long as you aren't restricted too much), but workload issues for the controller may end that.

 

[eetrojan]

There is nothing wrong with loitering in Class C. Some folks like to do airwork southwest of SJC. A local examiner has even expressed a desire to give checkrides there, though I'm not aware of anyone actually doing that. There is surprisingly little traffic there. Just tell Approach what you want to do. They may say no if you're in a bad place such as near an instrument approach or departure (the most commonly used southbound DP is why you won't get away with this northeast of SJC).

Once you've done this a few times, you'll learn that the point of Class C is to force you to talk to ATC, and not a whole lot else. It's really not a big deal. The key is advising your intentions. When I transition SJC, I know the controller's big concern is how I interact with the extended centerlines, so I'll usually volunteer that. "NorCal Cessna 123XY at 1500 request midfield transition at 3500"

You can even loiter in Class B once cleared (as long as you aren't restricted too much), but workload issues for the controller may end that.

Thanks for the explanation MAKG1! I get the impression my instructor wanted me to simplify the logistics of this short flight by circling in POC's delta, rather than circling in ONT's charlie, so that I only need to talk with SoCal-POC, rather than SoCal-ONT-POC.

 

[Irish_Armada]

Excellent graphic to go along with your question, by the way. It's always helpful to see examples from others' airspace conundrums and hypotheticals ... helps with the continued learning process. No better place to learn to deal with airspace than good ol' L.A.

 

[MAKG1]

Thanks for the explanation MAKG1! I get the impression my instructor wanted me to simplify the logistics of this short flight by circling in POC's delta, rather than circling in ONT's charlie, so that I only need to talk with SoCal-POC, rather than SoCal-ONT-POC.

Actually, in the Class C shelf, you will most likely be talking to SoCal anyway. Generally (but not always), the tower only handles the lowest altitudes in the surface area in Class B, C, and even D.

In my last Class C transition, I got an instruction to fly direct Palo Alto. I'm virtually certain that the point was to keep me off the extended centerline from SJC and that I could have asked for and gotten anything I wanted southwest of SJC if I had different intentions from that. But since I didn't ask for anything, I had to follow the instruction given.

I didn't get a single traffic advisory through that transition. On a nice CAVU Saturday where PAO was busy as a hornet's nest.

 

[bobmrg]

Actually, in the Class C shelf, you will most likely be talking to SoCal anyway. Generally (but not always), the tower only handles the lowest altitudes in the surface area in Class B, C, and even D.

In my last Class C transition, I got an instruction to fly direct Palo Alto. I'm virtually certain that the point was to keep me off the extended centerline from SJC and that I could have asked for and gotten anything I wanted southwest of SJC if I had different intentions from that. But since I didn't ask for anything, I had to follow the instruction given.

I didn't get a single traffic advisory through that transition. On a nice CAVU Saturday where PAO was busy as a hornet's nest.

Not familiar with SoCal airspace, but up here in the Seattle area the top 500 feet of Class D airspace at all local airports belongs to the TRACON per letter of agreement....so you can be in what appears to be tower airspace and not be talking to them at all.

Bob Gardner

 

[eetrojan]

Not familiar with SoCal airspace, but up here in the Seattle area the top 500 feet of Class D airspace at all local airports belongs to the TRACON per letter of agreement....so you can be in what appears to be tower airspace and not be talking to them at all.

Bob Gardner

Hi Bob, that's interesting. Are pilot's made well aware of that? Also, is any of the Class D space up in Seattle covered up by some Class C space?

There's only 700 feet between Bracket's TPA and the overlying Class C shelf. If the top 500 of Brackett's Class D airspace didn't belong to them, they wouldn't have much space to control:

 

[eetrojan]

Actually, in the Class C shelf, you will most likely be talking to SoCal anyway. Generally (but not always), the tower only handles the lowest altitudes in the surface area in Class B, C, and even D.

In my last Class C transition, I got an instruction to fly direct Palo Alto. I'm virtually certain that the point was to keep me off the extended centerline from SJC and that I could have asked for and gotten anything I wanted southwest of SJC if I had different intentions from that. But since I didn't ask for anything, I had to follow the instruction given.

I didn't get a single traffic advisory through that transition. On a nice CAVU Saturday where PAO was busy as a hornet's nest.

Hmmm. I would definitely have prefered to circle at 3000 in order be about 1,000 feet above POC's TPA, rather than at 2500 feet and only about 500 feet above TPA.

Do you think I would get a favorable response from SoCal if I asked them to circle in ONT's shelf at 3000 feet over POC?

 

[kkoran]

Let's look at this from the controller's point of view.

The controller tells the pilot to contact Bracket tower when the plane is 7.5 miles from the airport at 3500 in Class E airspace. It's 5 miles from the point the controller shipped the plane to tower to the edge of the Class C shelf. He expects the pilot to descend to pattern altitude (approximately 2000 MSL). From the controller's perspective, the pilot has 5 miles to lose 800 ft. This shouldn't be an issue since the pilot only has about 6 miles to get to pattern altitude.

Now let's also consider that the controller who shipped the pilot to tower might not be the controller responsible for airspace that includes the Class C shelf (note that the Approach freq in the box SW of the Class C says to contact SOCAL on 121.3 while the box NW of the Class C, and the SOCAL freq listed in the AF/D entry for POC, say 125.5).

If the pilot subsequently enters the Class C airspace, I think it's going to be up to the pilot to justify why he violated § 91.130. Clipping the Class E probably wouldn't be an issue, but if it causes an issue for the controller (or maybe he had an incident the day before, it might not be pleasant.

 

[CaptLabrador]

This is one of those threads that really reminds me that every pilot should visit and tour a artcc or tracon facility. That way you talk to controllers and see how things happen on their end. The controllers and towers all coordinate with each other "off line" so in the scenario presented above by kent it is highly unlikely because even if your not on a typical frequency the controller is most likely talking to the normal controller or tower and its easier than having the pilot change a bunch of freqs to keep him on one. If you ever hear them say "off line" and you have to repeat yourself that means they were on a phone coordinating with a tower or other controller.

 

[MAKG1]

Hmmm. I would definitely have prefered to circle at 3000 in order be about 1,000 feet above POC's TPA, rather than at 2500 feet and only about 500 feet above TPA.

Do you think I would get a favorable response from SoCal if I asked them to circle in ONT's shelf at 3000 feet over POC?

I can't say.

It might be a clue to check out KONT's instrument procedures. If there is one nearby, and it's in use, it's going to be a no-no. For instance, circling over KHWD (which has a similar configuration to KPOC) inside KOAK Class C ain't gonna happen. KOAK's conga line is right overhead at 2000, for the ILS to 29! It's close enough that KHWD has a 600 AGL pattern on the bay side.

If you spend time at KPOC regularly and never see any overhead jet traffic, it may be OK.

 

[eetrojan]

I can't say.

It might be a clue to check out KONT's instrument procedures. If there is one nearby, and it's in use, it's going to be a no-no. For instance, circling over KHWD (which has a similar configuration to KPOC) inside KOAK Class C ain't gonna happen. KOAK's conga line is right overhead at 2000, for the ILS to 29! It's close enough that KHWD has a 600 AGL pattern on the bay side.

If you spend time at KPOC regularly and never see any overhead jet traffic, it may be OK.

Thanks. I'll look into that and see if I can learn something.

I'm not yet sure what it means, or if it relates to the instrument procedures, but I note in the TAC first shown above there are a series of faint blue arrows from the departure end of ONT's runways 26L and 26R. They turn and then pass right over POC.

 

[bobmrg]

Hi Bob, that's interesting. Are pilot's made well aware of that? Also, is any of the Class D space up in Seattle covered up by some Class C space?

There's only 700 feet between Bracket's TPA and the overlying Class C shelf. If the top 500 of Brackett's Class D airspace didn't belong to them, they wouldn't have much space to control:

No, it is not well understood by pilots in the area. It is not uncommon to hear someone call the tower asking for permission to transit the Class D at an altitude more than 2000' above the field and have the tower send them to approach control or for an instrument student to ask approach for a freq change to contact the tower only to be told "Stay on my frequency."

There is no Class C airspace in the Puget Sound area.

Bob

 

[MAKG1]

There is no Class C airspace in the Puget Sound area.

There is a pretty substantial Class B, though. Isn't that mostly the same issue?

 

[MAKG1]

Thanks. I'll look into that and see if I can learn something.

I'm not yet sure what it means, or if it relates to the instrument procedures, but I note in the TAC first shown above there are a series of faint blue arrows from the departure end of ONT's runways 26L and 26R. They turn and then pass right over POC.

Looking into that, I see two problems with circling above KPOC.

(1) The VOR approach to KONT 8R has a holding pattern at POM VOR, directly overhead, at 4000.
(2) The ILS for KONT 8R has an initial approach fix and a different holding pattern right outside Class D, at 4000.

The missed approach holds for 26 are all around PDZ VOR (the other way), so maybe you'll get away with it if 26 is being used, but it's quite unlikely if 8 is.

The departure procedures also pass over KPOC, but at higher altitudes.

 

[eetrojan]

Looking into that, I see two problems with circling above KPOC.

(1) The VOR approach to KONT 8R has a holding pattern at POM VOR, directly overhead, at 4000.
(2) The ILS for KONT 8R has an initial approach fix and a different holding pattern right outside Class D, at 4000.

The missed approach holds for 26 are all around PDZ VOR (the other way), so maybe you'll get away with it if 26 is being used, but it's quite unlikely if 8 is.

The departure procedures also pass over KPOC, but at higher altitudes.

Thanks MAKG1. Next time I have the opportunity, and assuming it's not too busy, I'll ask SoCal if this is a practical option and see what they say.

 

[bobmrg]

There is a pretty substantial Class B, though. Isn't that mostly the same issue?

He asked about Class C and I replied to his question. Class B, as you very well know, is a whole different ballgame.

Bob