Because the planes are taxiing they wont hold 100% throttle (I think that's it basically, it's what appears to be happening). At a guess you're on the PMC terrains? Either way, you could brute force it with an eachFrame event handler (setting velocity and direction constantly). But for proper runway operation that's not going to be enough. I needed AI to use the runways on one of the PMC maps, and also wanted some ILS functionality for players, so I worked out how to add modded in runway objects that add each runway as a class: https://community.bistudio.com/wiki/Arma_3:_Dynamic_Airport_Configuration   I did it for the 4 airfields on Montenegro, including taxiways. It wasn't the easiest thing I've had to figure out.