Instrument Training: Instrument Scan, Part 1

Common sense is your first priority

An instrument scan for flight by instrument reference alone is easy if you know when and where to look. Acquiring essential information is your objective. When you look at non-essential information you waste time, and your performance falters. Landing is a good example. If you look at non-essential information during the landing flare, you may prang the runway and damage your ego.

My first opportunity to observe instrument pilot eye movement came when I started teaching initial and recurrent instrument flying in simulators and flight training devices (FTDs) - it was an education. Some pilots' eyeballs spun like the lemons and oranges inside a Las Vegas slot machine, others fixated on the wrong instruments, and still others moved too slow. I couldn't make these observations in an airplane because the pilot wore a hood and also because I watched for traffic in visual conditions and watched the instruments in instrument conditions.

Pilots with slow eye movement performed best. They usually knew when and where to look for the task at hand, and when eye movement stopped, they were always looking at the attitude indicator (AI). These pilots were relaxed, and they had time to properly manage their radios and charts and monitor the aircraft's systems.

My desire to be a better instrument instructor motivated me to research all aspects of instrument flight training. Plenty of information was available, but when it was grouped together, conflicts surfaced. I wanted a method that would be easy for students to remember and use and that complied with my training philosophy of maximum pilot confidence and minimum workload.

My initial instrument training was based on the needle, ball, and airspeed principle. The airplanes I flew didn't have a standard arrangement for the six flight instruments - the heading, turn and bank, attitude, airspeed, and vertical speed indicators, and the altimeter. The turn and bank indicator was the primary gyro instrument, and its turn needle responded only to yaw. (The turn coordinator's miniature airplane responds to yaw and roll, and its increased sensitivity made the needle, ball, and airspeed principle difficult to apply.)

In 1965 the U.S. Army taught me the U.S. Air Force concept of primary and secondary instruments. Today, this method - supported by the FAA - is taught in most general aviation flight training programs. During this era, flight instrument location was standardized using the T arrangement found in most of today's airplanes. The upper three instruments from left to right are the airspeed indicator, attitude indicator, and altimeter. Beneath these three, from left to right, are the turn coordinator; the directional gyro, or heading indicator; and the vertical speed indicator (VSI).

Using this instrument arrangement, the Air Force (I believe) developed the concept of control and performance instruments, which was more suitable for jet airplanes. This method is based on the principle of "attitude plus power equals performance" - the primary, undeniable axiom of instrument flight. The control instruments are the attitude and engine power indicators. The performance instruments are the remaining flight instruments.

All three scanning methods - needle, ball, and airspeed; primary and secondary instruments; and control and performance instruments - have been taught to thousands of excellent instrument pilots, but you must think about one factor. Military pilots learn whatever the military teaches, because if they fail, other people are eagerly waiting to take their place. Fear of failure and extreme motivation does wonders to any individual's learning ability.

General aviation doesn't work this way. Up or out may be okay for a homogeneous group of individuals, such as those found in military or university flight training programs, but not for a heterogeneous group composed of individuals with varied ages, backgrounds, and non-aviation obligations and responsibilities.

These people often equate instrument training - and flying - with total frustration. An instructor can avoid this if he (or she) is patient and innovative, a good teacher's primary assets. The following approach has worked well for me and my students. It starts with my four-step scan procedure and some new terms that help to identify and remember specific objectives.

Step one follows the attitude-plus-power-equals-performance axiom. You use the AI and the tachometer or manifold pressure gauge only, but you should forget the term "attitude indicator." Call it the trap door, because if you don't give it the attention it requires, you'll think the bottom fell out of the airplane.

For the first instrument scan lesson, cover all the flight instruments except the trap door and fly the Boxing-the-Attitude-Indicator maneuver. This maneuver has two objectives. It proves that attitude and power are the keys to safe flight, and it reinforces the importance of control coordination and trimming.

Before you start, fly at a constant cruise or slow-cruise speed, uncover the VSI, set the trap door's pitch reference symbol to indicate a zero-pitch attitude when the airplane stabilizes at zero vertical speed (constant altitude), and then cover the VSI again. Now start a two-bar, nose-high climb. When established in this attitude, ask yourself whether you're safe. Answer yes only if you set climb power when you changed attitude. If you didn't change the power, the answer is no. Your actions were unsafe.

Here's the point. When you use a reasonable attitude and power setting, you're safe. You don't know the exact airspeed, rate of climb, or altitude, but you do know that you're climbing safely. As training progresses and you're allowed to scan the other flight instruments, you'll learn the attitudes and power settings that result in exact performance.

After establishing the proper climb, resume straight and level flight using cruise or slow-cruise power. Make a brief right turn and return to straight and level flight. Start a descent using the one-bar nose-down attitude. Again, you're safe only if you set minimum power when you changed attitude. Return to straight and level flight, make a brief left turn, and start another climb. Repeat the maneuver until the significance of the attitude and power axiom is second nature.

Always rough-trim the elevator after you set attitude and power. Later in training, you'll learn to fine-trim the elevator after airspeed stabilizes.

I used "boxing" to describe this maneuver for two reasons. First, the airplane's nose inscribes a box on the horizon. Second, your hands move in opposite directions whenever you change pitch attitude. Yoke back to climb and throttle in to add power, and vice versa for a descent. It looks as though you're shadow boxing in slow motion as you perform a mandatory, flight control coordination exercise - elevator/throttle coordination for maintaining constant airspeed.

Sharp instrument pilots have perfected this coordination skill, and it's the secret to maintaining airspeed when pitch changes occur. When the left hand moves the yoke forward, the right hand moves the throttle aft. When the left hand moves the yoke aft, the right hand moves the throttle forward. Yes, you also need to coordinate the rudder to maintain heading, but at this point I place primary emphasis on elevator/throttle coordination, the primary requirement for maintaining airspeed.

You can quickly master boxing the AI if you use the proper coordination skills and reasonable attitudes and power settings. In an upcoming column I'll discuss step two of my four-step scan. Until then, concentrate on this fact: Whenever you must redirect the airplane during instrument flight - attitude or power change - you must watch the trap door, establish the proper attitude, set power accordingly, and rough-trim the elevator. That's common sense. That's step one.