This is for music geeks only, but the drum sound on that song was invented by Phil and the studio engineers by accident. It's lots of compression to make the room sound big, and noise gates to make the sound disappear quickly. They heard it through another microphone in the room while Phil was drumming that was set up through the compressor (it was just for him to talk to the studio, not recording the drums) and it sounded so good it blew them away.

That was used on a different song but they came back to the technique for Air Tonight to give the drum entrance maximum impact.