Instrument Tip: Taking a risky turn

Now you must figure out why, and what you are going to do about it.

Instrument approaches can list circling minimums for a variety of reasons. Approaches that also have normal minimums list them as a means to transition an airplane from one runway to another after breaking out of the clouds. Others will list only circling minimums if the approach course is at too sharp of an angle from the runway, or if the descent from the final approach point is too steep. This is all very straightforward. The real question with circling minimums is whether you should ever consider using them.

Although it provides a lot of flexibility on an approach, circling to land can be a risky maneuver. Consider the requirements. For a typical light airplane you must stay within a radius of 1.3 miles from the end of each runway. If you go faster than 91 knots during the circling portion of the approach the minimums go up to 1.7 or 1.8 miles. The obstacle clearance is only 300 feet.

Put yourself in that situation for a moment. To successfully circle to land you must descend from the final approach fix, stopping no lower than the minimum descent altitude. In a nonprecision approach you may be droning along at low altitude for a bit before you see the runway. From there you must assess the runway environment, position the airplane on a downwind or base leg, finish any landing configurations, and land with a normal descent not exceeding 30 degrees of bank. Those are testing requirements, but they serve as a good guide for safe practices. This is all while staying within 1.3 miles from the end of the runways, and without ever losing sight of the airport.

In good weather this wouldn’t be hard. But obviously you are in that situation because the weather is less than VFR minimums. If the ceiling is high, circling might be as easy as executing a normal tight traffic pattern. But if it’s closer to minimums it means hugging the deck of the clouds while doing all the maneuvering. Rarely do clouds form one nice, solid, consistent floor. Usually you’ll see clag hanging down, rain, and other obstructions that make circling even more risky.

That brings up the issue of going missed. Many accidents have occurred on circling approaches, and it’s not a stretch to think that the missed approach considerations could be one reason. If at any point during the circling maneuver the pilot losses visual contact, he or she must immediately go missed. This presents a tricky situational awareness problem. The missed approach instructions call for a specific direction of turns based on the final approach course. On a circling approach you could be on a visual final approach to the opposite runway when a layer of fog cuts off all visual reference. Now which way do you turn?

According to the Aeronautical Information Manual, “Simply joining the missed approach ground track from the circling maneuver may not provide vertical obstacle clearance once the aircraft exits the circling area.” In other words, if you have descended below the minimum descent altitude and immediately start a turn after losing visual contact, you may hit something. The AIM recommends, “To become established on the prescribed missed approach course, the pilot should make an initial climbing turn toward the landing runway and continue the turn until established on the missed approach course.”

It’s for these reasons that many professional flight operations do not perform circling approaches. The risks are simply too high. It’s good practice that if an approach is available to a more appropriate runway to use that approach, even if takes extra flight time to get there. Or, if no other options are available, head to a different airport. Leave the low-altitude maneuvering for the sunny days.