A customer told me, recently, that he was told gate allocation at an airport is rather like playing Tetris. And on the surface, this is a wonderful metaphor. The pieces fall. You slot them in. The rows clear. You score points. Marvellous.
The trouble is, Tetris is a very, very good video game. Possibly the most elegant video game ever designed. And gate allocation is not a game at all.
Consider, for a moment, what actually makes Tetris work. There are really only three rules. The pieces fall on a fixed rhythm. The pieces are atomic, which is to say you cannot break one in half. And once you have placed a piece, it is placed. Frozen. Final. Those three rules are the entire game.
Now consider an airport. The aircraft, alas, do not arrive on a fixed rhythm. They are late, they are early, they divert, and occasionally they do not turn up at all. The aircraft are not atomic. You can take one, tow it across to another terminal halfway through its turnaround, and bring it back on the stand when it’s due to boarded. And every assignment you have ever made is, in truth, only a draft. Because reality keeps voting on your plan.
So the metaphor is not wrong by a little. It is wrong by all three of the things that make Tetris, Tetris.
But here is the part I find genuinely fascinating. The metaphor is not just wrong. It is revealing. It tells you, almost confessionally, that the vendor has built a tool which assumes the world is closed, atomic, and rhythmic. They have built, in effect, a Tetris engine. And then, with admirable honesty, they have told the customer about it.
So if you are buying gate-allocation software, my one suggestion is this. Do not ask how clever the algorithm is. Ask what the vendor’s favourite metaphor does for a living.
Because Tetris ends. Airports do not.