Berserker is able to utilize the F-15 fighter jet so skillfully because
What I've hidden under a spoiler does not in any way spoil any events to come for Fate/Zero. In fact, what I've mentioned has already been covered by the anime. However, due to the limitations of the visual medium, some information is lost in the transition. Not to mention what I've discussed will not even be explicitly mentioned in the anime.
What I've explained, if one is particularly sensitive to spoilers, is akin to revealing exactly why Saber's sword is invisible, for example.