A few seconds later, you hear the sound
Treetop training looks fun (they are always in pairs and I'm sure they are playing tag) but I imagine can be a bit tense...
Mind you - nothing beats the time as a kid when I got to watch a Vulcan doing low level aerobatics above the village I grew up in - an amazing sight and quite a remarkable sound!
Then there was the sight of the C-5A supply flights coming in, directly over the roof... easy to make out the tread on the nosewheel, and every detail of the fuselage. Wingtips out at about a 120-130 degree angle, looking up... will never forget that sight.
Shame I was colour blind and didn't get told till I was 15 (at which point my career choices were Astronaut, Fighter Pilot, SAR helicopter pilot).