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Running the Gantlet: The Circle-To-Land Approach

A circling approach can be an uneventful VFR circle-to-land, or it can be the dicey, high-stakes IFR ordeal that some pilots won’t go near -- and that's what we're talking about.A circling approach can be an uneventful VFR circle-to-land, or it can be the dicey, high-stakes IFR ordeal that some pilots won’t go near -- and that's what we're talking about.

WHAT IT IS
Without squabbling over terminology or the context in which it's used, one way to think of 'circle-to-land' is that the term refers to any approach that's to an airport, rather than a particular runway -- such as when the approach course is at an angle greater than 30 degrees from the runway. Other clues include:

  • When you see a letter instead of a number (like VOR-A) in the approach procedure name.
  • If the Terminal Instrument Procedures (TERPS) criteria dictate a descent greater than 400 feet per nautical mile, it may be considered 'circling' even if the final approach course is lined up with the runway!
Whatever the case, a circling approach can be quite benign. You fly an approach to one runway, but land on another. (Just be sure to remember that even if it was an ILS and you're landing on a different runway, the higher circling minima apply.)

THE PROBLEM(s) ... a rough sketch

  • For starters, you've got minimum obstacle clearances (just 300 feet, within each approach category). Add to that limited maneuvering space -- as little as 1.3 nautical miles from any runway boundary, for a Skyhawk. (FYI: These circling minima are smaller than the ICAO terminal instrument procedures criteria ... the obstacle clearance heights are less, too!)
  • The ceilings may already be low, if you're in it for real. There may be little visual references.
    Translation: You might be flying just below a 400 foot overcast, turning and trying to keep the runway in sight at the same time.
This basically becomes the worst of both worlds: a maneuver that's performed visually, while in poor visual conditions, combined with maneuvering by reference to instruments, when you're trying to maintain visual contact with the runway.
  • You will probably have to do all this right at the ragged edge of transitioning from instrument to visual references -- well known to be the most difficult phase of any IMC approach. Note: The circling MDA is a floor, but it’s wiser -- and perfectly acceptable -- to circle higher, as clouds and visibility permit.
  • Then there’s the traffic mix. If it’s marginal VFR, and you’re at a non-towered field ... it could be showdown time.
  • It might not be so easy to stay within the speed for your approach category unless you have the airplane trimmed out and you are familiar with the power settings needed in this situation. You may have the added distraction of jockeying throttle and pitch the same time as you maintain a safe speed that is also within limits for the approach.
COMPLICATIONS, COMPLIMENTS OF THE REAL WORLD
  • Dark of night, wind, or rain (things can get ugly), but I'm not done...
  • Most of these approaches are also associated with VOR approaches. What if your receiver is off by four degrees? It's still within spec, so you may not be aware of its subtle inaccuracies.
  • The VOR transmitter can be off by up to two and a half degrees and still be legal. And what if both errors conspire in the same direction against a hapless pilot? You'd probably slide right by the airport and never see it. And what if you don't?
  • For most circling approaches, the missed approach procedure is different. It will have you turning back -- before you go with the published missed -- to where you think the airport is. How lucky do you feel today?
THE BEST CASE
Say everything's tuned right, you nail it and there it is. If you do see the runway, that's just the beginning. You have to stay at the circling MDA until you're properly positioned for the approach to a normal landing (in other words, on a straight-in final). Once you descend below the MDA, obstacle clearance becomes your responsibility. With all the towers and other obstructions in the National Flight Data Digest, and the fact that some charts and approach procedure errors aren't corrected for several 56-day cycles, this kind of non-precision maneuvering isn't very conducive to a warm fuzzy. Your odds go up if there’s a VASI or PAPI; down if there’s no vertical guidance.

Inside Information: Many *carriers* won't allow circle-to-land approaches to be performed in anything less than VMC.

WINNING STRATEGY: For some, it’s 'Just don’t go near ‘em!' If you must, do yourself a favor and use the highest circling MDA. That simple change could give you a 2.3-mile circling radius instead of a tighter, torquing 1.3. Of course, depending on the ceiling, you might not have the option...

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