>>15354348You do sometimes have to take into account the Coriolis effect. And in fact the Coriolis effect comes out inherently in the derivation of the equations of motion of an airplane. You might be able to find manuscripts of early aircraft that take it into account. It can sometimes be omitted for simplification though (and professors even said we were assuming a flat Earth), and we often did in school because it makes the equations easier.
We also at times omitted gravity, friction, and non-rigid movement, but those all exist. It depends on your application and you'd be surprised at how much simplification equations often go through, to varying degrees of error. The Coriolis effect is mostly important when flying really fast or really high (and maybe really far). Like
>>15354338 said, it's likely more important for bullets because they don't have their own thrust and can only go in their single trajectory.
