Make planes have the correct speed in the game.
Configuration file: planespeed on|off|<factor>
Command line: -YP
TTD normally divides a plane's speed by four when calculating how fast it should move across the map. Thus it will seem really slow when compared to fast trains for example.
With this switch, planes move as fast as their speed indicates. This means that they will be extremely fast in the game, and are difficult to click on with the mouse unless the game is paused. However, they do have a speed consistent with all other vehicle types.
This does not affect anything except motion across the map, for example the speed used in the station ratings calculation is still calculated differently for planes.
If <factor> is specified, and is between 1 and 4, inclusive, the planes will move at <factor>/4 of their stated speed. A <factor> of 4 is default.