Digital Pilot

Maybe you cant match a computers precision, but these drills may help


Without a doubt, human brains are the fastest and most versatile computers in the world. Thats especially true when the humans in question are pilots, but when it comes to repetitive tasks such as monitoring the progress of a flight on instruments, pilots can learn a thing or two watching silicon-based computers operate.

Once a digital computer has been programmed to perform certain operations, it just keeps on cranking through it until told to do something else. It repeats what it does, over and over and over. The same way. Every time. Because of this, computers are ideally suited for repetitive tasks that need to be done consistently, uniformly and flawlessly.

In an effort to learn something about instrument flying, its helpful to look at some of the IFR operations pilots perform – from the perspective of a digital computer.

Straight and Level
If a pilot wants to make an airplane fly straight at a constant altitude and airspeed, the task is simple. Maintain heading (keep the wings level and the ball centered), establish the correct pitch attitude (angle of attack), set the throttle(s) at whatever power setting will maintain a constant airspeed, and trim the airplane.

A computer can do all that, too. Autopilots, of course, are computers. They simply mimic the actions of pilots. The control inputs have to be exactly the same. Autopilots with auto-throttle capability keep the airplane straight and level by doing exactly what a pilot does: leveling the wings, keeping the ball centered, maintaining constant, appropriate pitch on the attitude indicator, establishing the correct throttle setting, and trimming. Even without auto-throttle, the method is the same, since power settings rarely change during cruise flight.

When the computer is between the pilots ears, the sensors are pretty basic: visual interpretation of the sacred six. The standard six-pack of flight instruments – airspeed indicator, artificial horizon, altimeter, turn coordinator, directional gyro and vertical speed indicator – are found on most airplanes, and virtually all that do routine instrument work.

Autopilots dont have to look at instruments, but they go through a similar input process to fly the airplane.

For a simple autopilot to function, basic benchmarks like heading, altitude and airspeed have to be established in the consciousness of the autopilot. This programming establishes an equilibrium that tells the autopilot to maintain the heading, altitude and airspeed that it senses at that moment. Period.

Under this cruise control scenario, lift, weight, thrust and drag are balanced and all the autopilot has to do is to maintain the same values. Balance can be established for any stable flight condition, not just level flight.

The autopilot is connected to sensors that spell out the conditions its supposed to maintain and that alert it when one or more of the parameters have changed. Some autopilots use some of the same cockpit instruments as the pilot; others use a different set entirely. The computer then tells servos attached to the flight controls how to manipulate the controls to re-establish the original equilibrium.

If this sounds familiar, it should. Its exactly the same scenario that exists when a pilot notices the airplane is no longer where it belongs and puts it back.

Climbing, Descending, Turning
If you want to climb or descend on a straight course and constant airspeed at 500 feet per minute, the steps are simple. Keep the wings level and the ball centered; raise or lower the nose to the pitch attitude required to produce the rate at which you want to climb or descend; adjust the throttle to the power setting that will maintain proper airspeed during the climb or descent; and trim the airplane.

Whether pilot, autopilot or throttle-capable autopilot, whatever is controlling the airplane needs to keep those parameters in line to get the desired result. The same goes for turns.

During instrument flying, a standard-rate turn (three degrees per second) is the Holy Grail of turning. From constant speed level flight, bank the airplane to the precise bank angle for a standard rate turn. While in the turn, maintain the proper pitch attitude to hold altitude, adjust the throttle (if required) to maintain constant speed while you are turning, and trim the airplane to maintain that condition until you want to roll out.

There is a constant theme to all these strategies. Its mechanical, repetitive and relies on objective observations of how reality compares with a predetermined set of values. In short, its precisely the kind of job best suited for computerization.

Putting the Pieces Together
Instrument flying is basically simple because it is nothing more than a combination of simple, repeatable tasks necessary to fly desired headings, altitudes (or rates), airspeeds and flight paths. The tasks are straight and level flight, constant and changing airspeeds, constant airspeed climbs and descents (at specific rates), constant airspeed/constant rate turns (to specific headings/for specific times), combinations of the maneuvers, and smooth transitions from one maneuver to another.

If you can fly these simple maneuvers, and combine them with flying specific courses, reading approach plates and enroute charts, using a stopwatch, talking on the radio and doing a few other things like that, you can fly instruments.

First Things First
First, however, you need to be able to precisely, consistently and reliably perform each of the basic instrument flight maneuvers. Everything else is possible if the basics are reliably in place. Absent the ability to fly basic instruments, it just isnt possible to fly instruments safely.

Thats why the basic instrument skills have to come first – and they must be honed and kept sharp. That can be done, by the way, using any garden variety personal desktop computer. All you need is the most basic of flight simulators and the hardware necessary for rudder pedals and pitch trim.

To learn or hone basic instruments, you dont need to spring for a high-end model that will allow you to shoot approaches. You need to be able to fly heading, altitude (and/or rate) and airspeed. If you can do that, you can do most anything. Its nearly mechanical, especially if you look at it that way.

The first thing to do is to intellectually understand the procedures you need in order to perform every one of the core operations outlined earlier. In the airplane you fly the most now, do you know the specific pitch attitude required on the attitude indicator for each maneuver? What about the power setting? How much of a power reduction do you need for a 500 fpm precision approach descent or an 800 fpm non-precision approach descent?

For the time being, forget flying instrument approaches and concentrate on the basics. Make sure your basic instruments – the components of the approach – fall into place first. Practice these operations on the computer. Use the accompanying drills, either in the airplane or on your desktop PC. Do them over and over and over again – until you understand the mechanics involved and can reproduce the operations just like a computer (autopilot) can.

All that a smooth autopilot does is to repeat the basic processes over and over in the right combinations. So should you. If you can fly the descent, the airspeed and the heading, and then manage a consistent altitude after leveling off, thats all you need to do for now. Combine those abilities later with an approach plate, a stopwatch and all the rest.

Good Basic Instruments
Being able to consistently fly good basic instruments is nothing more than knowing what you need to do and seeing what is or is not happening by scanning the instrument panel. Once you interpret whats happening on the instrument panel, you simply apply the necessary pitch, bank and power to achieve specific headings, altitudes and airspeeds.

Dont complicate it. Thats all there is.

If you already fly instruments or are training for an instrument rating now, you intellectually know how to do all of the basics – or at least you did at some point. Use your personal computer (at zero cost per hour after setting it up) to practice until your performance becomes almost automatic.

For example, if youre in straight and level flight at 90 knots and you want to climb at 90 knots, advance the throttle to full power, keep the wings level and keep the ball centered while you raise the nose to 6 degrees nose high on the attitude indicator. Your particular airplane may be 4 degrees or 10 degrees or something else, but whatever it is will be consistent, reliable and repeatable. You can depend on it. Thats the pitch attitude and power setting you use for this maneuver every time you need to do it.

Trim the airplane, fold your arms in your lap and enjoy the trip.

You have to first understand in your head what the components are and how. Then just make them happen.

While youre climbing, lets say things get off track a little. Maybe you missed your target pitch attitude or some bumpy air bounced the airplane out of equilibrium. Thats OK, just return the airplane to where it belongs. Look at the instruments, see what they tell you and correct.

Everything starts with cross checking or scanning the instruments. If you dont see a deviation to begin with, you cant do anything about it.

The Process
The process of actually flying basic instruments starts with the scan. If your scan is too slow – as it might well be if youve laid off for a while – there is an easy remedy you can use: Know when and what to look at depending on what phase of flight youre involved in.

Automatically adjusting the flight controls to compensate for instrument readings falls back on the concept of primary and secondary (or supporting) instruments. Some people have learned the same notions under the labels of control and performance. If the details on this kind of stuff have evaporated from your memory over the years, theyre all described in just about any book on instrument flying. If you have old ones on your shelf, dust them off. If not, you might want to do something about that.

Primary/secondary or control/performance, the concepts establish the framework for interpreting the readings on the instruments, like the autopilots programming allows it to perform its job. Just like the computer, you have to know what youre doing. If its not in your head, it cant be in your hands.

A little purposeful thinking will go a long way towards rekindling your interest and induce you – if youre really serious about your instrument flying – to get back into the books. And it wont cost you a penny.

Start your thinking about basic instruments by thinking about your scan. The scan is nothing more than looking at the instrument panel and seeing whats happening. If youre losing altitude but dont see it happening, you cant be expected to do anything about it. Youll probably also miss seeing the airspeed increasing or the VSI showing a descent, too.

Evaluate your scan. Is it fast, accurate, sloppy, slow but careful … maybe even non-existent? To have an adequate scan, you must push yourself to perform faster or more perceptively. If you think your scan is too slow, you can do something about it – but you probably wont do that unless youre consciously thinking about improving it. Reflection and determination to repair your deficiencies are important.

When considering your scan, start off by thinking about your vision as well. Unfortunately, most optometrists dont say anything if youre close to good vision, and even AMEs have been known to let pilots with questionable vision slide on their medicals.

Well, close isnt good enough for pilots. Because I have to fly cross-cockpit instruments from the right seat when Im instructing, I have to wear trifocals. You probably dont have to do that, but if youre going to fly instruments, your vision has got to be the best you can make it.

If you need glasses or a new prescription, get them. Theres no substitute for good vision.

Next comes instrument interpretation. Seeing whats happening is just the first step. Next you have to correlate it with other things to verify that the changes that you think should be occurring based on your control inputs actually are taking place.

Understanding the concept of the airplane in equilibrium is a good first step. If the airplane is flying in level, straight, constant airspeed flight, it is in equilibrium. To an outside observer, nothing is moving. Its all still, quiet. Thrust, drag, lift and weight are in balance. The airplane is trimmed and the power is set. Hands off.

If one thing changes, a lot of other things will change as well. There will be indication(s) on the instrument panel somewhere – probably in more than one place. If the nose drops a bit, the pitch picture on the attitude indicator will show the nose slightly lower than it was before. The VSI will indicate a small rate of descent. The airspeed will start to build, ever so slightly – with no increase in power. All of these changes correlate to the original drop of the nose.

The laws of physics command that it must be that way, so any one of those indications will show the pilot that the airplane is starting to descend slightly. Even if you have a poor scan, four of the six instruments will indicate the nose has dropped, each in its own way.

The next step is to either accept the condition because thats the way you want it to be or, simply, to do something about it. Thats when and where aircraft control comes in.

This involves the manipulation of pitch, bank and power. What are the standard throttle/prop settings for straight and level flight at various speeds in the airplane you most often fly? What are the rates you normally use for climbs and rate descents? What about the pitch attitudes on the attitude indicator that match those various speeds and rates?

With the exception of changes induced by seasonal temperature swings and varying altitudes, these settings are always nearly the same for a given weight. If you can cite the pitch attitudes and power settings required for various conditions in the airplane you most often fly, instrument flying is a piece of cake if you have an adequate scan. Just put the pitch, bank and power where you want them to be.

The Bottom Line
Fly basic instruments by the numbers, just like the autopilot. It works every time. Basic instruments are both consistent and repetitive. They are generally performed the same way every time. There are no uncertainties. Everything is known, once you work out the mechanics.

You can fly basic instruments on just about any personal computer of recent vintage. One thing you should ensure, however, is that you also use rudder pedals and a stick or yoke that is equipped with elevator trim.

There are two good reasons for that. If you cant trim for a stable flight condition – just as you would in the real world – you cant fly instruments. If you dont have rudder pedals, you will not experience the torque effect and ball-out-of-center movement that manifests itself with changes of power and airspeed.

As you know, when you increase power and decrease airspeed the nose tends to move to the left and right rudder is necessary to keep the airplanes heading from drifting to the left. Without rudder pedals, your computer software will keep the rudder centered.

Your practice will be unrealistic because it strips away a layer of attention needed to make an effective crosscheck of your scan. You dont want that. You want the simulator to react as the airplane reacts, even if you cant feel it in the seat of your pants.

The equipment required is fairly simple. A basic desktop PC is probably powerful enough to run any of the popular flight simulator software. I use the Elite flight simulator software because it records the airspeed, altitude, track, etc. You can then print out your performance for detailed analysis – or bragging rights. For basic instruments, however, any simulator software will be adequate.

Practice basic instruments until youre pretty good – certainly within the basic standards of +/-10 knots, 10 degrees of heading and 100 feet of altitude. Then, all you have to do is put those basics together and, with a little more study, you can shoot the eyes out of just about any instrument approach ever approved by the FAA.

Trust me.

Also With This Article
Click here to view “Turns, Climbs and Descents.”
Click here to view “Pattern A, Pattern B and Oscar.”

-by Wally Miller

Wally Miller is a Gold Seal CFI with more than 7,000 hours.


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