Edit2: what's that "Pegas" unit on Broth3r and Positron debriefings?
That's the named ace for the mission. Up to this run, I always thought the requirement to make him spawn was taking out the bomber TGTs as soon as possible (which spawns a flight of F-18 TGTs, which in turn spawns a flight of Rafale TGTs, both of which don't appear normally), and Pegas would appear after the mission update assuming you kill those 2 fighter flights quickly as well. Except this time, I did all that until it was time to kill the Rafales, which I left alive so I could farm the respawns, so I expected the ace not to spawn. To my surprise, he did spawn at some point when the respawns were almost ending, so there's that.