Where to look when, and why
If the wings are level, the airplane won’t turn.
If pitch attitude is on target (and power is fixed) the airplane will do what you want.
Of course the real world intervenes with updrafts, downdrafts, and turbulence. The airplane will be pushed around some, and the pilot will have to correct the attitude in roll and pitch. The point is that if this correction is done promptly the airplane will not stray from the plan.
Let’s take cruise flight as an example. The power is fixed. The airplane is in trim for cruise airspeed. On an IFR clearance, our fundamental task is to fly a heading and hold altitude. Easy, right? Just keep the wings level and the pitch at 2 1/2° nose-up, or whatever the target is on your airplane. If a gust changes the attitude, fix it. So why is it so hard?
Well, there are other tasks. There are distractions – some of them self-inflicted. We look away, and when we look back we are in a 15-degree bank.
But we have already learned the solution – the scan. We make the artificial horizon our focus. When our eyes move, they move inside the Basic Tee, left to the airspeed indicator, right to the altitude, down to the directional gyro, and down and right to the vertical speed. The technique is to hold the head straight and move only the eyes, looking back at the A/H after looking at another instrument. All this we know.
So what am I getting at? Here is the question: If where the airplane is going changes, what happens first? If you can answer the question, you can set priorities in your scan. You can know where to look and when.
The Smart Scan
Let’s take turns, for example. You are still in cruise. You are holding a heading of 270°. It is a bit bumpy. In your scan you notice the heading – 280°. You need to get it back to 270°. What do you do?
First – what you don’t do. You do not want to fix your gaze on the D/G and roll left. That will de-stabilize both the aircraft and your scan.
Here’s the fix, in task order:
Your eyes flick down and read heading 280°. They do not linger. The image will stay in your head.
Your eyes return to the A/H. Correct roll & pitch if necessary, while your pilot brain does its calculations. This is where your perception actually “reads” heading 280°.
You realize you have to turn left 10°. You think about how you’re going to do that. You’re going to put the airplane in a left bank of 15 degrees. While you’re thinking, your eyes stay on the A/H, correcting back to level and 2 1/2° nose-up.
Your eyes still on the A/H, you roll into a left bank of 15 degrees. The roll takes one second. You count in your head: Roll – two – three – roll, and roll back to level.
Your eyes flick down and read heading – 270°!
Your eyes return to the A/H. Correct roll & pitch if necessary, while your pilot brain thinks of what to do next.
Notice that 90 percent of the time, your eyes are focussed on the A/H. No, make that 95%. That’s where you do not only your thinking and planning, but also where your brain reads the other instruments. It sounds crazy, but our perception actually works that way.
The same procedure works for holding altitude. You look – you see you’re at 7100 feet instead of 7000. Your eyes return to the A/H. You lower the nose to 0°. You fly in that attitude for, let’s say, twelve seconds. You return the nose to 2 1/2° nose-up. You check the altitude – pretty darn close to 7000!
You could call this technique the smart scan. In summary:
The A/H is home for your eyes. That’s where you think and plan.
Move your eyes, not your head.1
Never linger on an instrument other than the A/H. Your glance should take 500 ms or less (1/2 second).
If a correction is required, do it looking at the A/H the whole time.
When the maneuver is complete, check the result.
The above technique is really nothing more than an explanation of attitude flying, where you move the controls to achieve and maintain an attitude, and use attitudes to maneuver the aircraft. There are two benefits to thinking about flying this way:
The technique works just as well in VMC. Instead of the A/H, you are looking outside 95% of the time.
It works for any airplane. Between a Pitts and a DC-3, there is a big difference in control forces and movements. But if you do what is required to get the right attitude, you never notice the difference.
This is another related technique made possible by GPS (or INS/IRS, for that matter). Navigation (and IFR approaches!) depend on holding the desired track. Traditionally we have done so by trial and error, holding a heading we think will work and then correcting for drift, and finding a heading which results in the desired track. Of course as we descend on approach the wind will usually back and decrease (in the Northern Hemisphere) and so we will need to change heading.
GPS calculates actual track about once per second, so if we make TRK = DTK (on a Garmin 430 default nav page, for example), and if we’re on track to begin with, we will not stray from the track.
The problem with this method is that the Garmin 430 is usually far from the A/H, and moving the eyes that far (or worse, the head) can de-stabilize the scan. The solution is a glass Primary Flight Display that includes track, such as the Aspen P1000 Pro. The track is the small aqua diamond on the tip of the track arrow.
1 Why? Because the semicircular canals in your ears are rotational accelerometers. They allow you to walk upright. But in IMC if you move your head they send you confusing signals, making disorientation and “the leans” more likely.