GA Circling Approaches
Intro
Circling approaches are among the more difficult tasks on the Instrument checkride. In addition to flying an approach, you’ve got to maneuver the airplane with precise tolerances near the ground, look for pattern traffic, plan a potentially windy missed approach, and deal with unfavorable winds. In the somewhat scripted scenario of IFR training and evaluation in GA aircraft, they are a necessary evil. This article covers techniques to make these GA circling approaches as manageable as possible. Out there in the real world, you should think very carefully about the threats involved and strongly consider alternatives like picking a different approach or landing somewhere else.
Prerequisites
Before you start circling approaches, you should have a solid set of fundamentals on which to build. Know your pitch and power settings for your aircraft (especially wind adjustments), how to stay in the energy box, chart annotation and briefing techniques, the basics of circling approaches as outlined in the Instrument Procedures Handbook Chapter 4, and the grading standard in the Instrument ACS. I also recommend backseating a few other students who are learning it so that you can get a better idea of what to expect before you do it yourself and thus cut down your training costs.
Planning
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Your planning will take one of two forms: your instructor/evaluator assigning an approach and asking you to execute it, or you selecting one of your own volition because you think it’s better than the alternative. In our case, let’s use the example of the RNAV 34 into Arlington, WA (KAWO).
Wind During cold front weather, it’s common to get breezy winds out of the southwest. Let’s say you get winds 200@10. (Technique tip: scribble this on your chart with an Apple Pencil in ForeFlight for better SA). In general, it’s easier to circle on the downwind side of the runway, because a) it gives you more time and a shallower profile to adjust on the base, and b) requires less total turning to get aligned on final. As you go from a left crab on downwind to a right crab on final, you need less than 180 degrees of turning. In this case, that means left traffic to 16. A good memory aid for this is that “the wind pushes you into the corner.” Sketch a wind arrow on your chart, and the direction it’s pointing is where your base turn should be. |
Downwind is usually the place to be. Think “the wind pushes you into the corner.”
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If the VFR chart says we RP 16, we RP 16....
Closures, Notes, and Traffic Patterns
Unfortunately, life isn’t always as easy as we want. Although we’re IFR, we’re still required to comply with 91.126(b) as outlined in the 2014 Krug LOI, which essentially says “Fly the VFR traffic pattern unless an ATC clearance or chart notes explicitly allow you to do something else.” In our example with the winds from the southwest, the VFR sectional says “RP 16,” so we need to circle on the less-ideal side.
Unfortunately, life isn’t always as easy as we want. Although we’re IFR, we’re still required to comply with 91.126(b) as outlined in the 2014 Krug LOI, which essentially says “Fly the VFR traffic pattern unless an ATC clearance or chart notes explicitly allow you to do something else.” In our example with the winds from the southwest, the VFR sectional says “RP 16,” so we need to circle on the less-ideal side.
If you’re wondering why they don’t put that on the Instrument Approach Charts, someone’s asked that question already. I don’t know if they have an upvote function. Back to the drawing board. I like to find all constraints on where I’m not allowed to go, and scribble it on my chart in red lines in ForeFlight to make sure I’m not tempted to go over there. This means that the new least-worst option is to circle on the upwind side. Something to keep in mind is that your 1-mile protected area should give you plenty of space to fly a normal pattern offset. If you get too close to the runway, that will cram up your base turn and you will overshoot or end up high on final. ForeFlight has a good overlay for this. Another technique in G1000s is to set your range ring on the MFD to the closest radius and monitor the XTK (cross-track error) to maintain SA.
Circling Altitude
The Instrument Flying Handbook 10-20 says “It is important to remember that circling minimums are only minimums. If the ceiling allows it, fly at an altitude that more nearly approximates VFR traffic pattern altitude. This makes any maneuvering safer and brings the view of the landing runway into a more normal perspective.” Basically, pick a number from MDA up to the VFR TPA that doesn’t put you back in the soup and discuss the plan with your instructor/evaluator so you’re on the same page. One consideration is that a different altitude will affect where on the approach your level-off occurs, so mark that on your chart and avoid turning until you’re inside the protected area. In our example, I’d assume with the 1400-foot broken layer and the breeze that we might have ragged bases in addition to the tailwind on base, so I’d prefer to stay lower to mitigate the likelihood of re-entering the soup or overshooting base. Let’s have 840 be our brick floor, and 940 be the top of our box. I like to set mins for the middle of the box for two reasons:
Circling Altitude
The Instrument Flying Handbook 10-20 says “It is important to remember that circling minimums are only minimums. If the ceiling allows it, fly at an altitude that more nearly approximates VFR traffic pattern altitude. This makes any maneuvering safer and brings the view of the landing runway into a more normal perspective.” Basically, pick a number from MDA up to the VFR TPA that doesn’t put you back in the soup and discuss the plan with your instructor/evaluator so you’re on the same page. One consideration is that a different altitude will affect where on the approach your level-off occurs, so mark that on your chart and avoid turning until you’re inside the protected area. In our example, I’d assume with the 1400-foot broken layer and the breeze that we might have ragged bases in addition to the tailwind on base, so I’d prefer to stay lower to mitigate the likelihood of re-entering the soup or overshooting base. Let’s have 840 be our brick floor, and 940 be the top of our box. I like to set mins for the middle of the box for two reasons:
- Most of us tend to see bugs as plus/minus targets, so it’s better to keep that practice and give ourselves target +/-50.
- Setting the mins in a G1000 or similar will give you an audible “minimums” callout. If you were focused elsewhere and missed that, you will have about 4 seconds from that callout to arrest your descent and stay in the box. If you set mins to the bottom of the box, then the callout will incriminate you when you bust the brick floor.
Drawing your circle and closed areas will help remind you of where to be and not to be, for there should be no questions
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Believe it or not, you are not required to stay at the MDA
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Descending from MDA
An easy way to plan a descent from MDA is to figure out where your normal pattern profile intercepts your circling altitude and plan that point to keep things simple. In a 172, I like to start my base close to 700 feet AGL. Looking at our Arlington chart, that means we pull power back to 1500 as we start the base, and make small corrections as needed. If your airplane’s FMS allows you to draw range rings, extended centerlines, and other visual aids to plan altitudes and aid SA, by all means utilize them. Read the user guide, watch videos, or talk to an experienced instructor for those.
Planning the Missed
A close read of AIM 5-4-21 is in order for this part of the process. Paragraph b. says that the missed procedure will only guarantee obstacle clearance if initiated at the MAP at MDA. Paragraph c. is worth quoting in its entirety:
If visual reference is lost while circling-to-land from an instrument approach, the missed approach specified for that particular procedure must be followed (unless an alternate missed approach procedure is specified by ATC). 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. Inasmuch as the circling maneuver may be accomplished in more than one direction, different patterns will be required to become established on the prescribed missed approach course, depending on the aircraft position at the time visual reference is lost. Adherence to the procedure will help assure that an aircraft will remain laterally within the circling and missed approach obstruction clearance areas. Refer to paragraph h concerning vertical obstruction clearance when starting a missed approach at other than the MAP. (See FIG 5-4-30.)
Paragraph h. tells us, in part:
The published missed approach procedure provides obstacle clearance only when the missed approach is conducted on the missed approach segment from or above the missed approach point, and assumes a climb rate of 200 feet/NM or higher, as published. If the aircraft initiates a missed approach at a point other than the missed approach point (see paragraph 5-4-5b), from below MDA or DA (H), or on a circling approach, obstacle clearance is not necessarily provided by following the published missed approach procedure, nor is separation assured from other air traffic in the vicinity. In the event a balked (rejected) landing occurs at a position other than the published missed approach point, the pilot should contact ATC as soon as possible to obtain an amended clearance. If unable to contact ATC for any reason, the pilot should attempt to re-intercept a published segment of the missed approach and comply with route and altitude instructions.
Boiling this down gives us the following rules:
- Turn initially toward the landing runway and then rejoin the published missed.
- Past the MAP or below MDA you need a new plan for obstacle clearance.
How should we rejoin?
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Before the MAP and at/above MDA, turn back toward the missed and rejoin
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There are a few hypotheticals for “here’s where you go missed” that we can consider and then condense into some simple rules.
If you’re not yet abeam the MAP (purple dashed line, above), and still at MDA, you can turn toward the landing runway, climb, and rejoin the track of the missed with a pretty straightforward right turn. That will satisfy both rules.
If you’re past the MAP on midfield downwind, the simple rejoin would not necessarily keep you in compliance with rule #2, so you need to climb before you rejoin the missed. Your initial turn to the runway will need to be followed by a turn to gain altitude before you leave the protected area. Keeping in mind that you’re not allowed to go east, your best bet is to turn south over the runway, overfly the approach end 34, then turn right to rejoin the missed. Overflying the MAP at or above MDA in your turn will ensure you meet the obstacle clearance requirements for the rest of the missed approach. If you look at that rejoin arrow (below, left), it’s basically the same as the original one from the abeam point.
Let’s say you’re on base, and there’s another unfortunately misplaced little cloud. Start your climbing turn toward the runway, stay south until you’re high enough to turn back toward the missed, then turn and rejoin (below, right).
If you’re not yet abeam the MAP (purple dashed line, above), and still at MDA, you can turn toward the landing runway, climb, and rejoin the track of the missed with a pretty straightforward right turn. That will satisfy both rules.
If you’re past the MAP on midfield downwind, the simple rejoin would not necessarily keep you in compliance with rule #2, so you need to climb before you rejoin the missed. Your initial turn to the runway will need to be followed by a turn to gain altitude before you leave the protected area. Keeping in mind that you’re not allowed to go east, your best bet is to turn south over the runway, overfly the approach end 34, then turn right to rejoin the missed. Overflying the MAP at or above MDA in your turn will ensure you meet the obstacle clearance requirements for the rest of the missed approach. If you look at that rejoin arrow (below, left), it’s basically the same as the original one from the abeam point.
Let’s say you’re on base, and there’s another unfortunately misplaced little cloud. Start your climbing turn toward the runway, stay south until you’re high enough to turn back toward the missed, then turn and rejoin (below, right).
Going missed from the downwind: turn toward 16, then back towards the MAP to rejoin the 34 missed.
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Going missed from the base: turn toward 16, then back towards the MAP to rejoin the 34 missed.
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Take the final hypothetical: you’re about to touch down and you see (or your evil instructor tells you there is) a herd of deer on the runway, so you need to go around. Here’s where a bit of common sense is in order: you’ve already turned toward the landing runway, so now you need to climb and rejoin the missed. Climb over the runway, then turn near or just south of the MAP. You should be above the MDA when abeam, then rejoin.
As you’ve seen, these hypotheticals all have similar shapes, so we can genericize a bit to make it simple: sketch an abeam line just shy of the MAP so that you can rejoin at or above the published missed. Anywhere past that line, start a climbing turn first to the intended landing runway, then back toward the MAP, and a final turn toward the original missed approach. If you’re below the MDA at the abeam point, throw in a 360 in the same direction and then join the missed.
As you’ve seen, these hypotheticals all have similar shapes, so we can genericize a bit to make it simple: sketch an abeam line just shy of the MAP so that you can rejoin at or above the published missed. Anywhere past that line, start a climbing turn first to the intended landing runway, then back toward the MAP, and a final turn toward the original missed approach. If you’re below the MDA at the abeam point, throw in a 360 in the same direction and then join the missed.
A balked landing on 16 means you need to climb back to the MAP, then turn and rejoin.
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If the last three looked similar, it's because they are. Here's your generic missed approach plan.
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Keeping in mind that turn radius scales as the inverse square of speed, a small GA airplane flying at a Vy of 70-80 knots will have a tight turning radius. Avoid using more than 20 degrees of bank to get back on track, as that will sap vertical lift.
Sequencing the Missed in the Box
If you’re using a G1000 or other FMS, make sure you know how it responds to circling approaches. The G1000 doesn’t seem to have a concept for circling, so it will follow the triggers in the database as if it were on the straight-in. In the case of the RNAV 34 at Arlington, the instruction is “Climb 1000 then left turn direct SAVOY.” If you mash the missed approach prompt in the climbing turn, it will execute that left turn as soon as you reach 1000 feet. If you went missed out of the base, this means you might be climbing through 1000 feet down near the MAP, which is not where you’d be on the straight-in. If you sequence it early, it might draw you a pink line in the wrong area. Wait until you’re back on the published missed to sequence, then sequence and follow it.
Sequencing the Missed in the Box
If you’re using a G1000 or other FMS, make sure you know how it responds to circling approaches. The G1000 doesn’t seem to have a concept for circling, so it will follow the triggers in the database as if it were on the straight-in. In the case of the RNAV 34 at Arlington, the instruction is “Climb 1000 then left turn direct SAVOY.” If you mash the missed approach prompt in the climbing turn, it will execute that left turn as soon as you reach 1000 feet. If you went missed out of the base, this means you might be climbing through 1000 feet down near the MAP, which is not where you’d be on the straight-in. If you sequence it early, it might draw you a pink line in the wrong area. Wait until you’re back on the published missed to sequence, then sequence and follow it.
Sequencing the missed too early will draw you a pink line in the wrong direction.
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Sequencing the missed when re-established will put your pink line where it should be.
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OEI Considerations
If you’re circling in a twin, you should have a plan for what to do if an engine quits. Many light twins won’t have enough OEI climb performance to go missed at 200 ft/nm, so you should plan to continue to the runway in some capacity. In a Seminole, I’ll plan a clean approach at 100 KIAS at 16-17/21 (MP/RPM), depending on winds, then level off at Mins/TPA using 19/21, then going T-GUMPS abeam my spot and landing. Depending on the approach, runway, weather, and other factors, you should consider if it makes more sense to abandon a circling approach in an engine failure case and land straight-in with a tailwind, or feather it and continue the circle. Clean at 100 KIAS gives you some latitude to trade 10 KIAS for profile/altitude if the engine quits in the worst spot (e.g. level-off at MDA), and if you’re close to sea level you can afford to tolerate a few seconds of windmilling as you manage the workload of the OEI flow while flying a circle. In any case, your circling speed and selected radius/category should account for blue line or maneuvering speed. If your instructor or evaluator suggests doing a circling approach in a light twin in the real world, think about the risks and consider refusing the flight if you think it’s a bad idea.
Note for instructors: OEI circling presents many threats. I recommend giving it to your students in a sim session to help form an appreciation of the complexity, but avoid doing it in the airplane.
VFR Traffic
If you’re flying practice approaches on a nice day into a place like Arlington, expect VFR traffic and have a plan for either avoiding it or playing nice. Unless it’s an IMC day and there’s nobody up, I usually help students with the VFR wrangling so that they can focus on flying. Announcing position and intentions on CTAF should fall on the student, negotiating holes in the pattern should fall on the instructor. In a real-world circling environment, there should be no VFR traffic, so it’s a bit unfair to throw a student to the wolves with all the responsibilities they already have. If it’s absolutely slammed, have a bail-out plan before you get there. An early climb before you get there and then the published missed is usually a good bet. That will keep you on your IFR plan and deconflict you with the VFR pattern. If there happens to be someone flying overhead to join, you might need to break off either side to avoid them. This can be stressful, so discuss the plan with your instructor/evaluator and have a specific phrase like “Breaking off approach, safety of flight” that you agree on as a signal to bail out and try it again another day or somewhere else. If you’re on a checkride or stage check, discuss the circumstances for discontinuing. It will get you points for risk management, and avoid you getting a pink slip for any cowboy stuff.
If you’re circling in a twin, you should have a plan for what to do if an engine quits. Many light twins won’t have enough OEI climb performance to go missed at 200 ft/nm, so you should plan to continue to the runway in some capacity. In a Seminole, I’ll plan a clean approach at 100 KIAS at 16-17/21 (MP/RPM), depending on winds, then level off at Mins/TPA using 19/21, then going T-GUMPS abeam my spot and landing. Depending on the approach, runway, weather, and other factors, you should consider if it makes more sense to abandon a circling approach in an engine failure case and land straight-in with a tailwind, or feather it and continue the circle. Clean at 100 KIAS gives you some latitude to trade 10 KIAS for profile/altitude if the engine quits in the worst spot (e.g. level-off at MDA), and if you’re close to sea level you can afford to tolerate a few seconds of windmilling as you manage the workload of the OEI flow while flying a circle. In any case, your circling speed and selected radius/category should account for blue line or maneuvering speed. If your instructor or evaluator suggests doing a circling approach in a light twin in the real world, think about the risks and consider refusing the flight if you think it’s a bad idea.
Note for instructors: OEI circling presents many threats. I recommend giving it to your students in a sim session to help form an appreciation of the complexity, but avoid doing it in the airplane.
VFR Traffic
If you’re flying practice approaches on a nice day into a place like Arlington, expect VFR traffic and have a plan for either avoiding it or playing nice. Unless it’s an IMC day and there’s nobody up, I usually help students with the VFR wrangling so that they can focus on flying. Announcing position and intentions on CTAF should fall on the student, negotiating holes in the pattern should fall on the instructor. In a real-world circling environment, there should be no VFR traffic, so it’s a bit unfair to throw a student to the wolves with all the responsibilities they already have. If it’s absolutely slammed, have a bail-out plan before you get there. An early climb before you get there and then the published missed is usually a good bet. That will keep you on your IFR plan and deconflict you with the VFR pattern. If there happens to be someone flying overhead to join, you might need to break off either side to avoid them. This can be stressful, so discuss the plan with your instructor/evaluator and have a specific phrase like “Breaking off approach, safety of flight” that you agree on as a signal to bail out and try it again another day or somewhere else. If you’re on a checkride or stage check, discuss the circumstances for discontinuing. It will get you points for risk management, and avoid you getting a pink slip for any cowboy stuff.
Briefing
Before you launch, discuss your plan for all of the above and any other factors with your instructor/evaluator to ensure you have the same interpretation. That will avoid any confusion when you actually fly. Plan to mention to the approach controllers that you want to circle, that will adjust their spacing. Scribble PAST on your chart as a reminder.
Execution
If you’ve planned it all out comprehensively, the execution should be straightforward. Use the 21-GPA rule for your power settings down the approach, then when you get to mins, put your throttle back to 2150 (Cessna 172), give a two-finger swipe of nose-down trim, and make <50 RPM adjustments to keep it in the speed and altitude box. If you need to go missed: cram, climb, clean, confess, rejoin, then click.
Another Example
Let’s take a look at the VOR-A into Olympia (KOLM) and consider the plan if we plan to land 17. Does anything stand out?
VOR-A into KOLM. Where are the easter eggs?
Your easter egg hunt should alert you to the steep profile: we need to lose 2500 feet in 5.0 miles (TDZ is about .1 nm back from the VOR). 60:1 tells us that D nm = ∆h ft / (GPA * 100) ft/nm, so 5.0 = 25 / GPA, or about 5 degrees. We know that sink rate will be VS = 1.8 * GPA * GS, so 90 * 1.8 * 5 gives us 810 FPM. Power setting will be about 1500 in a 172, maybe lower. We won’t have much margin for profile correction if we get high without breaching 1000 FPM sink rate, so we need to start down promptly. We should leave the 3000-foot hold at .6 nm from HABOR, or 5.7 DME at our power setting and sink rate to hit HABOR on speed and path, then make small tweaks. Let’s say we want to circle to 26 because there’s a westerly at the surface. If we need to go missed anywhere in that protected zone, we’ll need to get re-established on OLM R-171 at or above the missed profile, which starts .3 DME north of the VOR. A left turn from final to 26 likely won’t cut it, so we’d need to do a right chicken jibe to get back on track. When we’re all done sketching, our chart might look like this:
I used to love giving this one to my instrument students as a homework project and then have them fly it in the sim. It was a great way to illustrate the importance of scoping the approaches out before going.
Conclusions
Circling approaches in GA airplanes are challenging maneuvers that can be made more manageable with proper planning. Drawing out and thoroughly briefing your game plan should help you get through your instrument checkride with fewer issues. Once you have your instrument ticket, consider the threats associated with real-world circling approaches. Keep in mind: the safest circling approach is the one you never fly because you spent the extra few minutes setting up a straight-in.