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#100 The 360 Degree Overhead Approach

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I am consistently impressed by this simple fact:  Most pilots cannot land power-off on a spot that is located 1200 feet directly below them.  If asked to land on that spot with a simulated engine failure, they will consistently overshoot it.  They overshoot it because most pilots rush their turns in a power-off accuracy approach.  Then they arrive at short final going like a bat out of Hell.  This high airspeed virtually guarantees that they will float forever and overshoot this basic accuracy landing. Why do they make these silly mistakes? Primarily because they will try to make one circle to the landing when they actually have plenty of room to make two or even three circles!  This is a maneuver that merits a lot of practice.  Y’know how everybody goes to “best glide” (There’s no such thing as “best glide”.  They probably mean “best L/D”) when confronted with an engine failure?  Well, that speed will get you the farthest, but why go to a speed that gets you farthest when the point to which you are flying lies directly beneath you?  Wouldn’t a slower speed that keeps you aloft longer (glider pilots call this “minimum sink”) be a more prudent choice?  Or why not use airspeed as one of the ways to adjust descent rate and thus accuracy?  Hmmm, just something to think about.

 Let’s put some of these maneuvers we teach into a logical order so that they become useful.

 In the last couple of years I’ve begun to really concentrate on a troika of maneuvers which will precede the Dead Stick Landing.   The first two are the Minimum Altitude Loss Power-Off turn and the 360 Degree Circling Overhead Approach. The third is the Landing in a Turn.

 Remember those pilots who couldn’t land on a target 1200 feet below them?  Don’t you be one of them.  Their biggest problem was that they made only one circle because they didn’t know how much altitude they would lose in a 360 degree turn.  Let’s not only learn how much altitude we lose in that turn, but also how to make such a turn with as little altitude loss as possible.

 Through experimentation we’ll learn that there are two main parameters to pay attention to in this minimum altitude loss turn:  Airspeed and bank angle.  The first one is easy.  Fly at Minimum Sink.  “Duh”.  The second one is a bit harder.  You’ll be faced with the choice of steep or shallow bank.  If you bank shallowly, you’ll give up less of the vertical component of lift, but you’ll take longer to complete your turn.  If you bank steeply, you’ll complete your turn in much less time, but you’ll be giving up much more of the vertical component of your lift.  With experimentation you’ll find out that it’s the steep bank which will lose the least amount of altitude.  Somewhere between 45 and 60 degrees of bank will work just fine.  Because “G” force increases stall speed and you’ll have to pull more than one “G”’ to maintain minimum sink in that turn, you’ll be on the verge of a stall so you must be perfectly coordinated.  Just for an example, let’s say that we discovered that this steeply banked, slow speed turn resulted in a loss of 500 feet in 360 degrees of turn.  That means that we could be abeam the point of intended landing only 250 feet above the ground and still make it.  That’s why those guys screwed it up.  They thought they had to be MUCH higher.  So let’s put what we’ve learned to use.360 overhead 001

 We circle right over the runway on which we intend to land.  Each circle has one segment that is right over the runway on an upwind leg.  That’s another area that most pilots get wrong.  They’ll circle with the center of their circle right over the center of the airport.  When it comes time to make that last circle they’ll be out of position.  The diagram above shows the proper position of the circle.

 Theoretically, the circles we fly could resemble a funnel like the one in which we drop coins and watch them spiral down to the bottom.   That’s because the angle at which we can glide will remain the same.  So the higher we are the further away from the runway we can be. As we descend in a similar spiral, each circle would get smaller as we maintained the angle to the point of intended touchdown. That’s an important thing to know, but in reality, I teach this technique with similar sized circles.  Even the first circle, high above the airport is roughly the same size as the last one down at about five hundred feet above the field.  I do that so that we get more circles and thus more and better practice at the technique.  It’s that last circle where awareness of the glide angle will become important.

 In the currently accepted method of flight instruction every student is taught to fly his pattern at “pattern altitude”.  Every airport has its published pattern altitude, usually 800 to 1000 feet above the surface.  That student is also taught to fly his downwind leg a certain distance away from the runway.  They are almost never taught to fly at the resulting angle from the runway.  My point is that the angle never changes, regardless of altitude. The only factors that change the angle are the glide ratio of the airplane you are flying and the wind.   If you are lower but maintain the angle, you will fly closer and your turn from downwind to final will have to be tighter.  The lower you are, the tighter that turn will have to be.  If we are spiraling down to the runway, maintaining that angle, it will be obvious to us when we should make the last turn to a landing.  There are several reasons I like this approach, but there is one that stands out and makes it well worth mastering:  If you are cruising along cross country, have an engine failure and spot a nice, but relatively short spot in which to land, how would you know what the pattern altitude is for that nice little spot.  You don’t know what the field elevation is.  Flying circles and angles will be the foolproof method to glide to a safe, accurate landing in that fieldEveryone who has flown with me or read my articles knows how fond I am of that metaphor of the chicken coming home to roost.  Well, here’s the chicken who is so important to the practice of the circling approach:  Everyone who has taken my master class or tailwheel endorsement course is familiar with the minimum altitude loss turn and the circling approach.  If they take the knowledge learned from that maneuver and apply it to the last turn of the circling approach, they realize that they can be a lot lower than they thought as they pass through the downwind leg.  This knowledge and the skill that comes from practice can really save their bacon in the event of an engine failure followed by a power-off accuracy approach to a landing spot of an unknown altitude.

If you practice this approach and use the technique of constantly asking, “am I high or am I low?” you’ll soon get proficient.  But you’ll never get proficient if you don’t practice it!

 I have to admit that power off accuracy approaches are the pilot operations on which I probably do the worst.  That’s why practice of these approaches is so important to me and maybe to you as well.

 Happy Swooping