Class D transitions

[scottcame]

On Sunday morning, I was flying VFR from KSBA to KHHR, avoiding the LAX Class B by going east around downtown LA. I do this occasionally to practice navigation, and often do it without flight following. But I did get flight following this time.

As I was approaching Santa Monica, descending down to 1500, the SoCal controller asked if I'd like a Bravo transition. I declined and confirmed I would remain clear. He said to be aware that there was Class D airspace ahead and that I might want to stay above it. I replied that since Class D entry requires only two-way radio contact with the controlling facility, and since I was radar identified and talking to him, I thought any Class D or C transitions were automatic unless I heard otherwise from him. He said I'd need to request a frequency change to Santa Monica tower as I approached the Class D, and request a transition from tower, which I did and it was no problem from there.

The way it works in Seattle (where I fly in the real world) is, the TRACON controls some upper portion of the Class D for airports like KTIW and KRNT that are under the KSEA Class B shelf. If you're talking to approach and plan to transition the Class D below that portion, ATC will hand you off to the tower (and, I assume, do a point-out to tower so tower knows who you are and what you're doing). It is not the pilot's responsibility to request the frequency change. If you transition the Class D at the altitude controlled by the TRACON, then you just stay with approach and are none the wiser that the coordination between approach and tower is happening in the background. Sometimes the approach controllers will ask about route and altitude so they can plan things, or sometimes they just infer it based on course and current altitude.

It seems odd that it's the pilot's responsibility to request a frequency change. If I were on this same flight but headed to KSMO, I would expect the TRACON controller to terminate radar services and hand me off to KSMO tower at the appropriate point. So why is it different for a Class D transition? Asking the pilot to make the request is one more radio transmission that could be avoided...with perhaps more if the pilot requested it too early, or for traffic or some other reason TRACON wanted to keep the aircraft on frequency for a bit longer than usual.

I have no idea how this scenario would play out in real-world SoCal, but it would be interesting to find out. I do recognize that procedures are different in different real-world ATC facilities.

So...what's the rule for operation on Pilot Edge? Is it the pilot's responsibility to negotiate Class D transitions with the surrounding radar facility (TRACON or Center), or do (should) the controllers handle that seamlessly?

Thanks.
--Scott
N400SC

[Eugene Zaporozhets]

Hey Scott, great question.

I was the controller working your flight yesterday. I don't have a reference to how real Socal handles Delta transitions, but looking at the AIM 3-2-5, it says "Two−way radio communication must be established with the ATC facility providing ATC services prior to entry and thereafter maintain those communications while in the Class D airspace. Pilots of arriving aircraft should contact the control tower on the publicized frequency." Since it talks about the ATC facility "providing services" rather than just any ATC, my expectation is that a pilot would be in contact with the tower controller responsible for the airspace during a transition.

The radio handoff to tower is a bit tricky since I don't know whether a VFR pilot actually plans to transition through a Delta airspace or maneuver around it, hence I figured you'd call if you wanted to pass through KSMO. Class C is a different story. Approach and tower share the inner ring at different altitudes, and in that scenario I would've given specific restrictions to keep a pilot above the tower's shelf.

My perspective is limited by what I read in the AIM and the ATC order .65, though. I'm sure someone with experience will either confirm this or correct me if I'm off.

[Andrew Doubleday]

This has definitely been a topic we've been discussing recently...

The way you describe it, Scott, I would think SoCal probably operates quite similarly to your experiences in Seattle. I'm planning on making a trip out that direction to possibly see a few towers/SoCal and even the center if possible and this is definitely one of many questions I intend to bring up with controllers to see how traffic is moving around certain sectors/airports. It would make sense to me, especially in the aspect that a majority of towers in SoCal tend to have a radar feed of some form or fashion to reference traffic, that they are accomplishing Delta transition via some sort of automated point-out to the affected towers.

[Keith Smith]

From the VFR pilot's perspective, you should not assume that it's ok to enter the Delta if you're not talking to the agency that controls that airspace...and as far as you're concerned as a pilot, that would be the tower controller.

If you're IFR and getting vectored for an instrument approach where the approach takes you through Class D airspace, it has been coordinated and you needn't be concerned.

It is true that approach will often coordinate transitions for VFR aircraft, but if they haven't, and you bust the Delta...that could fall back on you (real world), so it's best to find out, or remain above that Delta.

If a controller is too busy to coordinate the transition, or too busy to monitor your flight to see if you might actually clip someone's Delta, he/she may issue an 'at or above' restriction to keep you clear of it. For example, when pilots are doing the V-2 flight (SNA-ONT), as an approach controller, I'll often issue an altitude restriction to keep them above the Chino/Riverside Class D airspace.

[scottcame]

I can see Eugene's point and understand the references to the AIM, but it still seems like the TRACON controller could either ask the pilot's intentions as to route (and transitions needed), or in rare cases where it's necessary, instruct the pilot to remain clear of the Class D and/or at a particular altitude. On one of my frequent sightseeing flights around Seattle, I basically fly around KSEA under the "middle" shelf, and when proceeding southbound to the east of KSEA, about half the time I'm instructed to remain clear of the KRNT Class D...the other half of the time, I just proceed on flight following and never hear anything about Renton, even though I fly right through the Class D.

http://skyvector.com/?ll=47.52413647717 ... 128&zoom=2

Keith, just saw your post when I tried to submit this. I agree that by a strict reading of the FAR and AIM, your point is a reasonable interpretation. All I'm saying is, that is not the way it works in the real world in the Seattle TRACON. The TRACON management is on record, at various pilot events that they've held, that they will either handle the transition or issue the handoff. Before I knew about that, I used to ask on frequency, and each time I got the same answer: "We'll handle all Delta airspace transitions for you..." So I now feel confident enough in proceeding without asking.

Anyway...glad to hear you guys are working on sorting this out. Perhaps not the most likely scenario, but in the LA basin it will occur from time to time, considering all the Class D airspace that's under the Bravo shelf. For now, on PilotEdge, I'll ask the approach controller about transitions.

Thanks for the help!
--Scott

[Keith Smith]

Scott, that's a fair point. If the pilot has advised ATC of their route, and the route is gong to take them through Class D airspace, then in absence of hearing anything from ATC to the contrary, the transition has probably been coordinated.