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 #203, “S” Turns

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I’ve lately learned that “S” turns, an accuracy technique which was taught to me and which I tend to take for granted, is not universally understood by most pilots.  As those who’ve flown with me know, I do tend to be a little obsessed with accuracy and the need to practice it as preparation for an engine failure which may never happen to you.  What they may not know is the reason for that obsession:  I suck at it.  From the time I started to learn to fly, I’ve always been bad at accuracy.  To quote myself, practice is the key to mastering this important area of piloting, so I’ll take my advice and keep working on it.

The “S” turn is an invaluable tool you can use to get your unpowered airplane back down to the proper glide path if you find yourself high.

Just as most pilots end up high on the glide path because they couldn’t control their urge to turn TOWARD the runway, the “S” turn is a technique that gets us low because, in its purest form, the S turn causes the airplane to continue its descent while getting no closer to the runway, thus adjusting the glide path.

The Tailwheel Town 140 turns across the approach course.  Its new course will take it ACROSS the final approach course so that it will lose altitude without getting any closer to the runway.  That’s why the “S” turn works.

Many of us are very hesitant to ever turn our back on the runway when low.  It’s not a bad rule.  It’s also one that you can easily follow while executing “S” turns in order to get back down to the proper glide slope while on final.

But if you are one of those who is afraid to bank steeply at lower altitudes, you may be doomed (see, Acme strikes again when they teach never to make steep turns close to the ground!) Because if you don’t bank steeply when it’s time to reverse course and go back across the extended centerline while “S” turning, you will find yourself closer to the threshold and still high. You will have “lollygagged”[1]your way around the turn and gotten closer to the threshold as a result.

In the illustration above, the pilot of plane “A” is making steep turns and doesn’t get significantly closer to the runway, although losing altitude and becoming more accurate. The pilot of “Plane B”, however, is making shallow banked turns as a result of his “Acme” training. His resultant “S” turns aren’t that effective.

The illustration shows why it’s important to make that steep turn.  To coin one of my favorite phrases, this is another case of “chickens coming home to roost”.  If the gang at “Acme” taught you to never make steep turns close to the ground, you won’t be able to properly take advantage of the S turn.  To make “S” turns effective, you really need to make steep turns.  To make steep turns safely, you must be coordinated and understand the effect of “G” force on stall speed.  Look at those chickens flappin’!

We look at the technique of S turning as a tool to correct a high approach.  I also teach the circling approach as the way to accurately approach to land in an engine failure situation.  But it should be noted that a pilot who is comfortable with steep turns can also use the technique to “lurk” and descend on the downwind side of an emergency landing spot.  He then turns in on final when his distance and altitude fall into place.

The “S” turn is also an extremely valuable tool in the box of every pilot who feels, like I do, that we must have the necessary skill to land out of any approach when a go-around is not an option.  If you don’t feel confident with doing “S” turns, then practice them with an intentional high approach once in a while.  And if you don’t think it’s worth the time, perhaps you should quit flying. A lot of people get a real kick out of playing bridge…

Happy Swooping,

Brian

[1]“Lollygagging” is the practice of using a very low bank angle during a turn, thus increasing the size of the turn and the amount of altitude lost in that turn.  It is used by under-trained pilots in a mis-guided attempt to increase safety. Those who observe the shallow banked turn don’t understand the role of “G” force in increasing stall speed.