tbh, airborne & parachute divisions are kind of in an awkward spot in HOI4.
The airborne landings on D-Day, and the large operations of Market Garden & Varsity, only translate to single-province attacks, given the scale of the map.
So a single battalion of coast guard troops in the coast forts of Normandy, can somehow also simultaneously occupy all the farmland south of the beaches, enough to effectively prevent parachute landings.
HOI4's parachute penalties, mean that airborne attacks against occupied provinces are extremely unlikely to succeed. 80% penalty to ORG for 96 hours, means paradropped divisions are likely to get de-org'd and destroyed long before the battle concludes.
So instead, parachute divisions are best used to drop behind enemy lines into unoccupied provinces. This only really works in North Africa, where there's a thin strip of provinces, and it's possible to trap opposing forces into a pocket. It can sometimes work in Italy too, since most of italy is only 3 or 4 provinces wide.
The range of transport aircraft and the numerous other issues with paradrops (there are many many threads where people struggle to understand why their airborne divisions aren't parachuting), just add to the problem of paratroopers being of limited real use.
Should the mechanics be reworked, then I would like air supply and paradrop missions for transport aircraft to be reworked.
Air supply should be a separate function, possibly several different functions, to allow people to mod things as they see fit.
1. Air supply from airbase-airbase, by aircraft landing at the destination, which allows a lot of supplies to be carried, over long distances.
2. Air supply by air-dropped containers, would be shorter ranged.
3. Dropping paratroopers.
4. Towing gliders for glider troops.
Capacity of the aircraft should matter. This could allow mods for things like the Me323, if there is an attribute for how much supply each aircraft can carry.
The size of the airborne division should also affect the number of aircraft required to transport it, again, dependent on the capacity of each aircraft.
Older strategic bombers, could be repurposed to perform the roles 2,3,4, again, dependent on capacity of aircraft.
Airborne operations were extremely affected by the amount of transport aircraft available - Operation Market Garden required basically the Allies entire fleet of transport aircraft, and it was still not enough to do it in one drop, and that was only ~3 divisions.
Hoi4 allows you to do drops much larger than Market Garden, and with a lot fewer aircraft. This doesn't seem right.