Routine in the sense of a normal mission that was nothing out of the ordinary prior to the midair, whether a weapons school mission or a test/eval squadron mission, both of whch operate out of Nellis. Sadly, midairs between A-10s have occurred a good number of times in its career just due to the nature of ops. 5 that I can think of off the top of my head, 2 of those having occurred during my time in the Hog, 1 that I was on scene for. The 2 that occurred during my time, 1 was at Nellis in the NTTR and occurred during a rejoin, 1 jet lost and that pilot....Nutt Polaro...ejected through a fireball that burned up his parachute pack and he fell to the desert floor. The other was near Douglas, Az in the Tombstone MOA with 3 A-10s I was working with: one A-10 coming off a dive bombing run collided with the FAC A-10 orbiting overhead. Both pilots ejected, but Romance Donelley slipped out of his parachute harness when the main canopy deployed and fell to the desert floor 10,000' below. Didnt see him, but saw the collapsed chute drifting down with no one in it.
So yeah, these things happen during what otherwise wouldve been routine training missions.