The primary weapon, killing machine of the First World War was field artillery. Artillery pummelled the lines, dugouts, rear trenches, rail lines, and, quite often, other side's artillery.
The most important functions of the aircraft were reconnaissance and artillery spotting. The first was needed for identifying changes in the enemy lines, equipment, supplies,etc. and targets for the artillery. The second was a direct teamwoork with the artillery.
It would be really neat to have field artillery that functioned not only as a backdrop to the game, but a function of the game. If a recon plane brings back target photos, an artillery barrage will try to take out the target.
Artillery Spotting would open up a whole new area in gaming. Imagine standing in the back of an Albatros C.VII(or the front seat of a BE2e, that's scary!) and direct artillery with signals from your telegraph key. You can even see your army's artillery shells whizz by. Hope one does not hit your plane or it will smash it up there only to fall to earth.....