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If I'm flying along in my C-152 and I am trying to go in a straight line through the "center" of C airspace (to land at a regional airport under the airspace), but the controller tells me to remain clear, what should I do?

Would it be safe to fly under the C, or above it, or would it be best to completely circle around even if it takes extra time and fuel?

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    $\begingroup$ Technically speaking a clearance is not required for class C airspace. All that's needed is to establish and maintain two-way communications. Most class C ceilings are only 4000 feet so flying over is pretty easy. $\endgroup$ – Steve Kuo Jul 20 '14 at 0:42
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If I'm flying along in my C-152 and I am trying to go in a straight line through the "center" of C airspace, but the controller tells me to remain clear, what should I do?

Well, the obvious answer is remain clear of the Class C airspace :-)

HOW you remain clear is entirely up to you - you can go over, under, or around - you just can't go through, and I think that's the more interesting part of your question.


Flying around the class C airspace is usually a safe choice (don't skim along the margins though - give it some reasonable breathing room), but as you've noted it could add a lot of time/fuel. You need to balance that with the time/fuel required to climb above the airspace, or the risks of flying under the airspace (mainly obstacles) to make your decision.

I'm going to use my local class C airspace as an example for an exercise in aeronautical decision making because conveniently there's a VOR you could hypothetically be circling while talking to approach, and an airport on the other side you might want to get to.

In our hypothetical example let's say you're circling Deer Park VOR (A) at 2500 feet, and you want to cut through the Class C airspace to get to Brookhaven (B), but approach isn't cooperating.
Islip class C
Click to embiggen.

I've got three options sketched out here - think about them, then hover over the spoiler boxes for my thinking on each of the three routes:

  1. The dashed line through the center (the route you were hoping Approach would give you).

    A straight line is the shortest distance between two points, but this straight line stinks: Since Approach wouldn't let you go through the class C airspace you're going to have to spiral-climb to 4200 feet or higher (5500 feet if you're playing by the hemispheric rule), and then when you get to the cut-out in the class C on the other side you're going to have to dive down to get to pattern altitude.
    That doesn't seem safe, nor efficient to me, so let's toss that idea out the window.

  2. The northern route under the class C airspace.

    Simple enough, we'll split the difference between the ground (roughly sea level) and the floor of the airspace (1500 feet) and fly under the shelf at 1250 feet. Plenty of room above and below (if your altimeter is set right and you're any kind of decent pilot).
    So this is the part where I confess that I'm a big ol' wuss and don't like to be close to the ground. It's like a porcupine, but with radio towers for quills (like the one I marked with a big OUCH - at 1250 feet there'd be less than 500 feet between my landing gear and the top of that tower).
    I'm not happy with the obstacle clearance on this route (and while I could certainly rearrange the line a bit to avoid the obstacles I'm not going to because they serve my purpose) -- the northern route is out.

  3. The southern route under the class C airspace.

    Same idea as the northern route - descend to 1250 feet and fly under the shelf, but I like this route a whole lot better.
    There are really great landmarks here ("Fly southeast toward the looped road, then go to the middle of the bay and stay between the two shore lines until you pass the bridge at Smith Point. At that point you'll see the airport off your left wing and can maneuver to enter the pattern.")
    You're also over water, and we don't tend to have any radio towers sticking up out of the bay.
    You'll need to watch out for traffic from Bayport, students practicing ground-reference maneuvers, and banner-tow planes in the summer, but that's just your basic everyday VFR "See and Avoid" situation.
    This is probably the route I'd pick.

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    $\begingroup$ Incidentally I think this might be the first time I've legitimately used the >! markdown spoiler tag. $\endgroup$ – voretaq7 Jan 25 '14 at 6:44
  • $\begingroup$ The only thing that I would do differently would be to fly at 500' below the shelf instead of "splitting the difference". $\endgroup$ – Lnafziger Jan 25 '14 at 12:41
  • $\begingroup$ @Lnafziger You can definitely get by at 1000' on the southern route over the water but over land you'd technically be in violation of 91.119(b) a lot of the time since all the suburban sprawl & houses are above 0' MSL & a lot of the area is considered "congested". $\endgroup$ – voretaq7 Jan 25 '14 at 18:59
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    $\begingroup$ @CJBS Emergency landing options are a great point! At the risk of too much of a spoiler, your landing options in both routes are kinda lousy (check out a Google satellite view). My personal preference is to add a few minutes and get out from under the class C entirely (and in winter, a further preference for the south shore as the barrier island has nice, straight, runway-like roads which tend to be empty in the off season). This example is obviously highly contrived, and ignores such real-world considerations as good emergency landing options :-) $\endgroup$ – voretaq7 Mar 25 '14 at 1:03
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    $\begingroup$ My choice would be option 4: It adds just a small amount of distance to option 3. Continue southerly to the ocean, fly eastbound along the beach outside the Class C airspace. The shoreline provides a unmistakeable reference to where the C ends. You will have a great view. The beach is a long emergency landing field (less crowded in the winter than in the summer), and you are not restricted as to altitude. $\endgroup$ – Skip Miller Apr 22 '14 at 13:44
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When the controller tells you to "remain clear" it simply means that he is too busy to help you out at the moment. Traffic situations change quickly though, so I would recommend taking the most direct route that you can while remaining outside of his airspace and when things sound like they have quieted down a little, give him another try. If it isn't feasible (you are landing at the primary airport, or you need to enter it to get to the other airport) then you can circle until things calm down for the controller.

Since the airport that you are wanting to land at is under the Class C airspace anyway, probably the best way would be to go ahead and descend a little earlier than you had planned and fly under the shelf. Assuming that you have sufficient terrain clearance it would probably be better than flying over the top since you have to go down there anyway. That being said, there's no reason not to fly over the top if it's more convenient!

In either case, the main thing to watch for is arrival and departure traffic for the primary airport. The controller basically told you that there is a lot of it. If you are instrument rated, take a look at the arrival and departure procedures so that you can try to avoid them.

Just be sure that you don't accidentally fly into his airspace without a clearance and you should be fine!

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As indicated in the other answers, "remain clear" means just that, and can happen when congested (as already indicated by @Lnafziger).

One approach that I take in the Bay Area to have a greater chance of getting into Oakland's Class C or SFO's Class B is to get a squawk code (with a flight following request) from another facility first, then get handed over. That way, it's just a matter of a frequency change and a hand-over. E.g. "N12345Z on frequency at 2000".

State to the first facility (squawk code assigner) what your intentions are so that they can give you the correct squawk code (they are different sometimes depending on whether you need to be handed off to another facility)

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