Sorry again - I am sure I found this issue somewhere a thousand times but am not able to find it again. Therefore need to repost to get some clarity.

Please consider this:

As you can see the whole team is mashed up at that point. They stall in air and cannot do stuff but crash into each other. One of the helicopters also is spinning around lol.
I watched that some time and then saw the infantry just jumping outside the vehicles in mid-air.

Questions:

How can I turn air transport completly off? I want the enemy OPCOM deliver his reinforcements only by CONVOY / Groundforces. It kills the immersion of my mission that these guys have hundrets of choppers flying around delivering only a jeep or something like that. Just feels wrong.

I'm not familiar with this, but I found some code on the wiki that might help: http://alivemod.com/wiki/index.php/Custom_Blacklists

You can probably set ALIVE_factionDefaultAirTransport for enemy OPCOM to [].

So, assuming the enemy is OPF_F, this might work

[ALIVE_factionDefaultAirTransport, "OPF_F", []] call ALIVE_fnc_hashSet;

I could be mistaken but if no faction assets are defined, it would typically default to side (BLU_F, OPF_F etc.). I've not tried defining faction with empty vrackets, but if you set logistics to faction only and don't define the faction's transport assets it will use the default/vanilla choppers & trucks.

Ok well but will this leave the logistics to ground convoy (trucks etc.) only?

Just remember that Arma3 AI are horrible at land navigating vehicles.

Yea but as horrible as this air drop stuff :D

Worse, because more often than not, your ground transport AI will never reach their destination.