The Swedish Army's popular HKP 5 show - 'The Flying Carpet' featured twelve aircraft in a formation, piloted by an Army flight instructor in each machine. The show featured some highly skilled formation flying, including this carpet formation, a thrilling split, flying in a row and forming a perfectly closed circle, flying in an 'eight' pattern and jumping over each other in the middle, and not to mention four machines autorotating to the ground together, and so on.
Here are two other images of the group together: 05224 & 05226.