As a professional pilot , I spend four or five days a year in multimillion-dollar flight simulators being examined by specialized training pilots. Since professional pilots already know how to fly, much of the testing focuses on what are called “non-normal situations.” Let’s imagine you find yourself on an airplane, in the sky, without a pilot. You are in a non-normal situation.

A useful guide to your initial actions if you’re in such a pickle is a simple mnemonic called ANC: Aviate, Navigate, Communicate. (Aviation is as acronym-laden a field as any I’ve come across.)

So, aviate. You need to keep the plane in the safe, stable flight you found it in.

Use the control wheel and the horizon displayed on the attitude indicator to level the wings. If it’s gin-clear outside and the real horizon is obvious to you, feel free to use it.

Next, take a look at the altimeter and the vertical speed indicator. Pick an altitude as your target—a simple number near your current altitude, like 10,000 or 15,000 feet. If you’re climbing away from your target, then very gently push the control column forward—that is, away from you—until you’ve stopped climbing. If you’re descending, then pull the control column back, toward you, until you’re not descending anymore. Be gentle, as it’s easy to overcorrect. Porpoising, or repeatedly ascending above and then descending below your target altitude, is a common problem for new pilots.

Now look at the airspeed indicator. Pick a target speed toward the higher end of the safe range. It’s impossible to give numbers for every airplane, but try 100 knots in a small plane, 250 knots in a small airliner, and 280 knots in something like a 747. If your speed is higher than your target, pull the throttles or thrust levers back slightly to reduce power. If it’s lower, then add power.

Excerpted from How to Land a Plane, by Mark Vanhoenacker, a 787 pilot for British Airways. He is also the author of Skyfaring: A Journey with a Pilot. Buy on Amazon. The Experiment

The goal is to reach an equilibrium in which your speed and altitude are safe and stable. Note the pitch attitude and power setting at which this occurs. The problem, as you’ll soon realize, is that the inputs required to correct one aspect of your flight path will almost certainly upset another one. For example, if you’ve just changed your power setting, then your pitch may have changed, and perhaps you’ve started to inadvertently climb or descend. Or, if you’ve accidentally lowered your pitch attitude, you’ll soon see your speed increasing and your altitude dropping.

The best way to catch such unintended changes early is to move your eyes between the primary instruments in a consistent pattern. This pattern is called the scan and the scan is, unfortunately, much easier said than done, in part because it can seem repetitive at first, and in part because you must keep scanning at the same time as you’re doing everything else you need to do. In fact, getting the scan right is one of the hardest parts of pilot training. It’s hardly overstating it to ask you to imagine that every remaining word in this article is followed by the command “Scan!”

Sometimes (Scan!) just (Scan!) maintaining (Scan!) level (Scan!) flight (Scan!) requires you to hold an awful lot of forward or backward force on the controls. This brings up the important concept of trimming. Trimming, you might say, is a way of resetting the conditions under which the controls feel neutral. Or to put it another way, a perfectly trimmed plane would carry on doing what you want it to, even if you were to let go of the controls. It’s hard to think of a good analogy from everyday life, but you could imagine a rower with one arm that’s a little stronger than the other. If his boat had a rudder to steer with, he could rejig the rudder slightly to one side, so that the boat would go straight ahead without any further steering inputs, even when he was rowing as hard as he could with both arms.