Trim Controls Airspeed

What causes an airplane to up or down, faster or slower?

Everyone who has never flown a plane knows that the throttle makes you go faster and the stick takes you up or down. Right?

Well, not exactly. This is actually one of aviation's biggest controversies, and what better way to start a general aviation blog than wading into it?

Of course actual pilots know that an airplane speed is based on a combination of stick and throttle position. Power + Attitude = Performance is the formula many of us have learned.

But is this even right? It is true to an extent, but is it helpful? When you're low and fast on approach, what do you change to get where you want to be?

Having gone through training in general aviation and the navy, I've seen different ways of going about it. My civilian training came first, so when I got to the navy I at first thought their approach something akin to an ill informed heresy. (Being an idiot when you're in your 20's is expected.)

In case you're wondering, navy doctrine demands that power controls glide slope (altitude), stick controls airspeed.

We could go into the whys and wherefores, but would it really make a difference? This is, like religion, an article of faith. But it's not a faith you have to accept completely on my word. Go out and try for yourself.

The easiest way to demonstrate is on final. Do this by controlling your airspeed with your trim. If you're off in glide slope, adjust your power, but leave the stick/trim alone (assuming you have the right speed).

Going back to our low and fast position, how would we correct? First crank in a little nose up trim. Depending on the size of your deviation, that may be all you have to do. Practically though, you're probably going to have to make a power adjustment. When you adjust the power, it will take three corrections- put in a correction, take it off, and put half of it back in again. The important point to grasp is that these power adjustments are meant to get your descent under control, not change your airspeed.

Before the engineers among you start to argue, can we all agree that we are ignoring some scientific matters in this formulation? The goal though is not to pass a science test, it's to learn how to better control an airplane. When you turn a car you don't worry about arcs and radii do you? I think you'll better understand and control your plane if you just admit that the navy knows something about landing and aircraft precisely.