The Race's killercraft were extremely effective in securing dominance over the skies. In the early days of the war, the Killercraft were able to totally destroy most a human air force at every engagement. One missile could go 10 times faster than the best human fighter. However, the Race had anticipated an easy victory. There were not enough killercraft to sustain the war. Also the Race's tactics of using killercraft were poor in comparison to actual aerial combat, given the fact that the Race had only two known battles in their thousand year-long history.
Over the course of the war, they mainly served in a ground attack role to great effect. This in particular led to several killercraft being destroyed by human anti-air guns. Britain began using airborne radar and Germany developed jet aircraft to have some success against the Race. As the war progressed though, advanced munitions ran low, and killercraft were unable to compete as succesfully with human aircraft as before.
Killercraft pilots were chosen for their aggressiveness. The craft themselves had an 18 missile capacity and were equipped with radar controlled cannons. They were also shielded from EMP, painted with camouflage, and specially modified to be capable of extremely high altitudes so that they could be picked up by orbiting ships in the absence of available airstrips on the ground.
During the Race-German War of 1965, the Germans han't quite closed the gap of technological quality with the Race in terms of jets, but possessed a numerical advantage.