I have now flown about 13 missions in Aviatik C.I and couple in Fokker E.III from November 1915 to January 1016. I have noticed that the default flight plan altitudes generally don't make much (or any) sense.
In the latest mission two flights of the Marine KEK were tasked with balloon protection flying Eindeckers. The final patrolling altitude was no less than 3000 meters and the other flight was even higher, waaaaaay too high for guarding a balloon that was at few hundred meters I thought. As I suspected, when a single Nieuport crossed the front lines we started an insane dive near the maximum speed of the planes (at least for player); when I was at 2000 meters the Niueuport had destroyed the balloon and was turning around;when I was at 1000 meters the Nieuport was crossing back into Entente territory. Having no chance of catching up at all (or before Calais). I gave up and started returning to base. The only thing that lifted my mood after that disaster was seeing that the two other planes of my flight had given up chase even earlier to continue patrolling around the destroyed balloon as if nothing had happened
. Going by common sense the lower balloon protection flight should be no more than 500-700 meters above the balloon with the covering flight significantly higher, there's just no way to get to the balloon level in time (and in one piece) from above 3 km in anything built before 1930's.
A lesser but constant altitude issues effects at least recon and bombing flights of early two-seaters. A typical flight into enemy territory has roughly the following phases:
#1 - Take-off and 4-6 km trip towards altitude building waypoint
#2 - Altitude gaining waypoint
#3 - Trip to mission waypoint near the front lines
#4 - Objective waypoint
#5 - Return waypoint near base
In phase #1 the planes rise to 200-300 meter altitude after take-off, then fly in formation and without altitude gain for several minutes to the altitude building waypoint. This entire trip is wasted in level flight instead of using it to climb.
At waypoint #2 the planes circle to altitude of 2000-2500 meters then advance towards waypoint #3 and only climb couple hundred meters on the entire long way. There is a great risk of enemy flights attacking from higher altitude as the flight is much lower than it could be.
At waypoint #3 the planes are entering AAA zone but this is when the target altitude actually increases by several hundred meters to above 3000 meters. The time spent in the AAA fire is maximized instead of breezing through at full speed. Also I don't really get the idea of the waypoint #3 in general, it usually does nothing but shifts the course slightly so that it makes the flight go directly over every possible ground unit, balloon and airfield before reaching target. It makes some sense for recon flights but is completely insane for bombing missions.
At waypoint #4 the flight has finally reached ceiling altitude above 3000 meters. This is fine for recon but if the objective happens to be bombing and there's heavy cloud cover around 1-2 km altitude it makes the already hard task of guestimating the handbomb trajectories without bombing sights or even downward visibility virtually impossible.
After finishing the objective at leisurely pace the flight heads back home towards waypoint #5 and immediately starts wasting altitude!!! About 1000 meters of altitude is wasted for no reason (while throttling down engines), a lot of it deep in the enemy territory. This obviously makes the flight increasingly vulnerable to intercepting and scrambled enemies that have been invited by the earlier airfield flybys and 20 minute loitering at the target (a carrier pigeon has probably reported the flight to Whitehall by this point).
Unless there are some strong historical reasons for such counter-intuitive flight plans, it would seem way more sensible to do something like this: Start the climb already on the way to #2; Get up to near the final altitude at the waypoint #2 and built the rest of the alitude on the way to #3 so that the unit crosses the front-line at cruising speed at mission altitude. Then return to home wasting little to no altitude and finally land at the airfield.
I know I can just ignore the waypoint altitudes when leading the flight (doesn't happen often because I'm still at the lowest rank) or change the waypoints with Mission Editor, but I really hope this is something that will be adjusted in the future patches.