What is remarkable about the 1940 mid-air collision that occurred over Brocklesby, NSW, Australia?

Both aircraft were part of the Royal Australian Air Force doing training exercises when the two planes collided one on top of the other. The two planes locked together and the top plane's engines stopped working while the bottom plane's engines continued. The bottom plane's crew ejected from their aircraft but the top pilot discovered he could actually control both planes with his flaps and rudders and managed to successfully land both planes. All 4 crew members survived and the damaged top plane was actually repaired and went back into service. Incredible!

https://en.wikipedia.org/wiki/1940_Brocklesby_mid-air_collision