There is no objective after all targets are destroyed, so consider it a free flight! Landing is possible, but you have to find a very straight piece of land, fly at around 350 and descend very slowly.
I appreciate your review! Flight physics are far from perfect, but the model itself indeed works as you described. It is very advantageous, since you get a lot of things for free, e.g. landing, taxiing and collisions. Realistic stratosphere / zero-g handling could also use the same model with minimal changes.
