Most people leave an air show remembering the noise. That is fair enough, because the noise is extraordinary, and it arrives in your chest before it reaches your ears. But the noise is the by-product. What you are actually watching is a small number of people solving a geometry problem in three dimensions, at speed, in front of an audience, with almost no room to be wrong.
Once you can see the problem they are solving, a display stops being a series of loud passes and becomes something closer to a performance you can read.
Every display is flown against an invisible boundary called the display line, running parallel to the crowd. The pilot flies on their side of it. The audience stays on theirs. Regulators set the distance, and it varies by country and by aircraft type, but the principle never does: no part of a manoeuvre may carry energy toward the people watching.
This is why displays look the way they do. Loops and rolls are flown along the line rather than pointed at you. When an aircraft appears to be heading straight for the crowd, it is almost always angling away, and the drama is a trick of perspective that the pilot has practised until it is repeatable.
It also explains the pauses. A display is not continuous action. The aircraft leaves the display area, repositions out of sight, and comes back on the correct heading. Those gaps are not dead time. They are the aircraft being set up so the next figure can begin exactly where it needs to.
A display pilot is managing one quantity above all others: total energy, split between speed and height. You can trade one for the other, and you can lose both, but you cannot conjure either back quickly.
Watch the start of any vertical figure and you will see the trade being set up. The aircraft comes in low and fast, converting fuel into speed, then converts that speed into height on the way up. At the top it is slow, and the pilot has very little left to work with, which is why the manoeuvre at the apex is usually gentle. Coming down, height becomes speed again, and the next figure can be aggressive.
A sequence is really a chain of these trades, arranged so the aircraft always arrives at the next figure with enough of both. Get one link wrong early and the whole display has to be softened to recover, which is a thing you can often see happening if you know to look.
Volume and proximity are the easiest ways to impress an audience, and the least interesting. The things worth watching for are quieter:
Aircraft are easier to identify by ear than by eye, and the sounds tell you what the engine is doing.
A few things make the difference between a good day and a long one:
The pilots are not improvising. Every display is a rehearsed sequence, approved in advance, flown to a script that accounts for the aircraft, the site and the weather on the day.
Air shows are one of the few places where an audience gets to watch a craft performed at its actual limit, in public, by people who have spent years earning the right to do it. The spectacle is real, but it is downstream of something more careful: preparation, restraint, and a great deal of practice at doing exactly the same thing the same way.
That is what the noise is announcing. It helps to know.