Eye of Experience #11:
Flying by Sight Picture

  • E-Mail this Article
  • View Printable Article
  • Text size:

    • A
    • A
    • A

Some pilots fly by the numbers, while others fly by attitude. AVweb's Howard Fried is in the latter camp, and thinks today's pilots are way too dependent on the airspeed indicator and have forgotten (or never learned) how to fly by

Eye Of ExperiencePitch to Altitude and Power to Airspeed?
... or Power to Altitude and Pitch to Airspeed?

Several years ago, a pilot examiner of my acquaintance would ask his private applicants one question and one question only during the oral portion of a flight test. The question was, "Which control makes the airplane go up?" If the applicant answered, "The throttle makes it go up," he passed the oral part of his check ride, but if he said the elevator makes the airplane go up, he failed the oral and thus the entire flight test!

Sooner or later, every student pilot becomes aware of the age-old controversy regarding which controls what: pitch for speed and power for rate of climb, or vice versa. Flight instructors often demonstrate one method or the other, depending on which the individual instructor favors. The power-to-control-airspeed demonstration goes like this: The instructor says to his student, "You think the elevator controls airspeed? Come on, let's see." They then taxi out, line up on the runway and the instructor starts to furiously pump the yoke (or stick) back and forth with the airplane remaining in place. Eventually, the student asks, "What on earth are you doing?" The instructor replies, "I'm trying to get up enough speed to take off!"

When asked the question of which does what, one prominent air race pilot responded, "All I know is, when I lose a race, I go out and get a bigger motor!" (I know, all you old Army Air Corps and Air Force guys are going to jump on this and tell me it is an engine, not a motor, but I was directly quoting the original.)

To demonstrate the power-controls-altitude approach, the instructor will take a student up to a nice safe altitude, retard the throttle to idle and say, "OK, you've got it. Now pull back on the yoke (or stick) and make it go up." Sure enough the airplane will do just that, briefly, as it zooms up until it runs out of poop. Then, it will quit flying altogether and start to descend. Obviously, there is an overlapping function of these controls and they both do both jobs in varying degrees, depending on the circumstances. In other words, a pilot can make either control perform either function at any given time. It is simply a matter of juggling the two controls to achieve a desired result.

Trim for Speed

Did you ever notice that when two pilots are occupying the front seats of an airplane and the one flying says to his companion, "OK, you take it for a while," that the very first thing the new guy at the controls does is reach for the elevator trim control and make a minor adjustment? Happens every time.

We adjust the elevator trim for a specific airspeed. This can be demonstrated quite easily. First, attain a nice, safe altitude. Then, in level cruise, adjust the pitch trim for hands-off flight at cruise speed and in cruise configuration. Now, reduce power to idle and watch what happens: The airplane will pitch down and speed up, pitch up and slow down, pitch down and speed up, pitch up and slow down; repeating this process through several (perhaps as many as half a dozen) oscillations until it stabilizes in a glide at the original airspeed .

Next, leave the trim where it is, apply climb power and again observe what happens. The airplane will pitch up and slow down, pitch down and accelerate (slightly above its original speed), and repeat this process through a few oscillations, each excursion becoming smaller until it once again stabilizes at the original airspeed , only this time in a climb.

Because most training airplanes are so light that they can be left in a sort of neutral trim and very little force is required to operate the controls, many instructors fail to teach their students proper trimming technique. And proper trim technique is particularly important when leveling off from the initial climb to set up the cruise configuration. The way it should be done is quite simple. First, level off at the desired altitude, then wait. After the airspeed builds up to cruise, reduce the power to the desired setting, trim for hands-off, and you're all set. Most pilots attempt to level off by rolling in down elevator trim until a level attitude is reached, simultaneously reducing power. This technique requires several adjustments until hands-off level flight at cruise speed is reached.

Juggling

That it is easier to juggle one variable than two or more should go without saying. Why then do pilots continue to play with both pitch and power on a VFR final approach? If the airspeed is set with pitch, then all that is required is to adjust the power to control the descent. Believe me, if you sight down the runway (not directly ahead, but slightly off to the side for better depth perception), bring the airplane down to a couple of inches off the runway and then hold it off the ground with the elevator as long as you can, your passengers will look around and say, "When did we land?" It will be so smooth you simply can't feel it.

An old instructor had an expression that has stuck with me for over 50 years. He said, "Take the slack out of the stick." In other words, maintain a steady pressure as you bring the elevator up. If you are abrupt, the airplane will zoom up a few feet and go THUNK, and possibly bounce. If you don't use enough back pressure, you will surely land nosewheel first and possibly bounce (or worse). By taking the slack out of the stick, the old guy meant that as the speed bleeds off, the stick (or yoke) will tend to become slack. Don't let it do this. Simply maintain a constant pressure until you are rolling on the ground. But don't forget to "fly" the airplane to ramp.

As for judging just where you will touch down, the old saw works quite well. You simply eye the spot you want and, if it appears to be moving toward you, you will land beyond it. If it appears to be moving away from you, you will undershoot. If, however, it seems to be motionless, that's where you will touch down. This has worked for me as I have won numerous spot landing contests. My basic policy has always been to never tell anyone how to fly. I simply tell 'em what I do and WHY. If they like what they hear, they can adopt the same procedures; if not, they may do as they please.

Takeoffs

The "sight picture" technique works equally well on takeoffs. The modern approach to teaching takeoffs favors holding the airplane on the ground on the takeoff roll until the magic number appears on the airspeed indicator and then ROTATE. Unless a precise airspeed is required for the climb (to clear an obstacle or get out of a tight place) this is totally unnecessary in a light fixed-gear, fixed-pitch-prop airplane. I suppose that some of the large flight schools, assuming that all their students are future airline pilots, started teaching this way ab initio so there would be no transition required. Then the FAA started recommending this teaching technique because they underestimate the intelligence of pilots. The Feds assume that a few years down the road, the student pilot will be flying a high-performance single or a twin in which this technique is required. Since the FAA believes pilots are too stupid to make the transition when the time comes, "we'd better teach ‘em to do this now."

I was taught — and I gave many thousands of hours of dual to primary students — using this procedure: Line up with the runway, apply full power and track straight down the runway using the feet to steer the airplane. As speed builds up, apply back elevator pressure until the nose of the airplane cuts the horizon, and then wait. When the airplane is ready, it will fly off the ground.

No Airspeed Indicator

A student pilot, working solo in the pattern at the airport where I am based, had been taught the "modern way" — to depend on the airspeed indicator. On the initial climb-out after a takeoff, he lost his airspeed indicator. (A spider had made a nest in the pitot tube.) The poor fellow declared an emergency and disrupted a busy airport while he made his way 'round the patch. He was thoroughly shaken by the incident, which should have been purely routine.

When I was trained in the old Army Air Corps, an experiment was undertaken with my class of Cadets. Throughout our primary training (sixty-five hours during which we were taught to do everything that can be done with an airplane) we never saw the face of an airspeed indicator. They had been physically removed from the airplanes. We survived by flying by sight picture and feeling (and otherwise sensing) the necessary speeds for each maneuver (including aerobatics).

Today, my policy is to not solo a primary student until he/she has twice flown the pattern with the airspeed indicator covered up. It's no big deal. Remember the formula that ALWAYS works: Power plus attitude equals performance. Apply this formula, fly by sight picture and I guarantee you'll enjoy your flying more, and be a better pilot for it. Although airspeed is critical in both instances, glider pilots and aerobatic pilots fly almost entirely by utilizing the sight picture technique. It is really the only thing that works for them, and you'd better believe their flying is much more precise than that of the average private pilot.

Other Senses

The term "flying by sight picture" refers not only to sight, but to all the senses. Hearing plays an important part in this technique. Of course, in an open cockpit airplane it is even more important as the wind rushes by, but a pilot can hear the changes in engine sound as the pitch changes even in a closed-cabin airplane. All kinds of subtle noises give one cues as to what's happening.

And the sense of touch is vitally important in this kind of flying. The tension on the yoke (or stick) and rudder pedals, and the amount of force required to move them tells the pilot a lot about what is being experienced: A lot of pressure indicates high speed and little (or no) pressure indicates the imminence of a stalled condition.

All the senses taken together create a genuine "seat of the pants" flyer, and despite all the modern technology and modern theories regarding flying "by the numbers," it is the seat-of-the-pants guy who has the most fun and enjoys aviation the most. If you've never experienced this kind of aviating, I urge you to try it. You'll like it!

Usual Boilerplate

Following the publication of my last column on "Who Needs an Instrument Rating?" I received over forty email comments and criticisms sent directly to me, and I answered every one of them. I do wish, however, that if you have a comment regarding one of my columns, you would post it here in the comments section so that others might share your input.

Thanks!