The Massed Approach/Crash/Airmiss used to be the finale to the Wallop Airshow. I did 3 or 4. If that's 1996, I'm in one of the wheeled Lynx. Experienced it once from the crowd line and it's very impressive(and noisy considering the Lynx and Gazelle must be two of the noisiest helicopters ever built) as they get close and closer.
We once topped the hundred mark with a bit of help from a couple of Pumas and a Chinook.