Tuesday: slow flight and steep turns

On Tuesday of last week, my joint flight to 29 Palms with Harold was called off due to high winds. Instead, we flew out to the barrens halfway between Apple Valley and Barstow and practiced a few maneuvers I hadn't done in a while: slow flight and steep turns.

Both are pretty sweet. With slow flight, you reduce the throttle (to slow down) and tilt the nose up (to maintain your altitude). I believe Harold and I introduced a little flap as well, just to give us more lift. Pow, there we were, cruising along at about 70 miles per hour or so, tilted back like we were doing a wheelie in midair, the land inching by beneath us. It's cooler than I made it sound, believe me. Normally a Cessna Skyhawk's cruising speed is between 100 and 120 miles per hour, depending on the wind. The plane becomes airborne at 60 miles per hour, so it's pretty impressive that we were still able to stay up and just inch forward at 70.

Why do pilots practice slow flight? Well, I'm glad you asked. It comes in handy for landings, that's why. Nose tilted back, throttle reduced, flaps down...that's a plane just about to touch down on the runway. Knowing how to bring the plane into and out of slow flight is essential for pilots. The only other thing you might use slow flight for is if you've roped some poor suckers into a flightseeing tour and you want to show 'em something reaaaaaaaaalllly cool on the ground. When you turn in an airplane, particularly a Cessna 172, you usually never go beyond what's called a "standard rate" turn: that is, 30 degrees of bank. Any farther and you're in a steep turn. You want to be careful with steep turns, because of a little thing I like to call the vertical component of lift.

When you fly level, like this...
...the vertical component of lift is king. That's what's opposing weight (see the aviation glossary at the bottom right for the four forces of flight) and keeping the airplane up. However, when you do a steep turn, like this...

...suddenly you don't have a vertical component of lift anymore, really, because the wings are tilted so much that they aren't lifting the plane up. What you have instead is the horizontal component of lift, which is the way the air moves over the ailerons and changes the direction of the plane. The reason you have to be careful is this: with steep turns, the vertical component of lift (which holds the plane up) is reduced severely, supplanted by the horizontal component of lift. If you reduce the vertical component too much...what's going to hold the plane in the air?
If you said "not a friggin' thing" you are CORRECT! Here, have a cigar. So what you have to do with steep turns is monitor four things very closely:

• airspeed: Too fast and you'll climb. Too slow and you'll stall and fall out of the sky. Make sure you've got enough throttle in to keep you in the air, but not so much that you climb. During your final flight examination (known as the checkride), you are expected to stay within 100 feet of your starting altitude while performing a steep turn. It's harder than it sounds.
• attitude indicator: A handy little instrument that tells you whether you're climbing or descending (pitch) and how far you're tilted right or left (roll). It rolls when you do, and pitches up or down when you do, so you can look at it and immediately know what your plane is doing. The instrument itself looks like this:
  For steep turns, you want one of those little orange wings in the center there pointing precisely in between either pair of hash marks (at ten and eleven o'clock or one and two o'clock, respectively).
• horizon (the real one): Keep your eye on the horizon outside the cockpit. Keep the nose of the plane pointed dead at it, not high, not low. (You can do this by pulling back on the yoke, or pushing it forward.) That way you'll stay level while turning.
• turn coordinator: This doohickie likewise tells you how much you're rolling, but it also has a little ball suspended in kerosene which lets you know if your turn is "coordinated" or not. Take a look:
  
  A coordinated turn is one in which all of the control surfaces are working in harmony and nothing's out of whack. A Cessna 172's propeller spins to the clockwise. That means there's a considerable amount of torque; the propeller keeps trying to pull the plane off course (even on the ground). So to counterbalance that, you have to keep a little pressure on the right rudder pedal to balance that torque out. When turning in mid-air, that torque will pull the ball to the left; right rudder will center it, and the plane will be straightened out and turn in a smooth and coordinated fashion once again. You really want to keep that ball centered, because if you happen to stall and it's not, that means one wing is going to stall first. And when one wing stalls first, you don't simply fall out of the sky. You go into a spin. A spin is just about the scariest thing that can happen in an airplane. So keep that ball centered! I think I've heard that directive from my instructors more than any other.

Without further ado, I humbly present the steps to doing a steep turn.

Pound in some throttle to speed up a bit and compensate for that loss of vertical lift. Roll the plane into a sixty-degree bank (right or left, whatever) with the aid of your attitude indicator. Monitor the turn coordinator to make sure the ball's centered, and keep your eye on the airspeed, all the while keeping your nose level with the horizon outside. Keep doing this until you do a complete 360-degree turn. When you get within 30 degrees of your original heading, roll out and reduce throttle. If you do it right, you'll wind up going the same speed you were before you began, at the same altitude, at the exact same heading.

It took me a little practice back in Cheyenne. It took one or two tries to remember here in California. But I got it. Soon I was pulling off slow flight and steep turns like a pro. As a postscript, I'd like to add that steep turns are probably not something you'll want to do if you're carrying passengers. Unless you like people barfing down the back of your neck, that is.