Airlifts

Airlifts allow the player to move units from one square to another on the map without any distance or terrain limits and costs. Both the start and the target square must have a property with the "Airlift" attribute set to true. The "Airport" property in the "Panama" scenario is an example of an airlift property square, allowing the player to move a unit from one of these squares to any other containing this property. New scenarios may contain different or additional terrain properties such as "landing strip" or even "highway" with this attribute set.

Unit Limitations

Units also have an attribute indicating whether the may be airlifted. Although most typical land-bound units can usually be airlifted, heavy equipment might have this attribute disabled. Check the scenario notes and unit type descriptions in each scenario to find out what is allowed. Of course, if you are playing a historic scenario, the American Civil War for example, you won't find either terrain properties or units capable of this move type. 

Air Defenses

If enemy units with the "Air Defenses" attribute are within striking distance of the starting or landing squares, the airlift will be endangered and any damage that an airlifted unit incurs will always be catastrophic, no armor or other damage reduction will be applied and the unit will always be considered lost.

Paratroop Landings

Paratroop landings differ significantly from airlifts. Although these also must start on a terrain with the property attribute "Airlift" set, they can target any terrain type with the "Paratroop Landing" attribute set. In the "Panama" scenario for example, most land squares with the exception of mountains and mountain peaks, are possible landing areas.

Paratroop Units

Each unit type carries an attribute "Paratroop allowed" which is set to yes or no. Only units with this attribute set to "yes" can be used for this purpose. The Panama scenario for example only allows a few unit types, such as seals, to be air-dropped.

Landing Zones

Since only one unit is allowed per terrain square, dropping paratroop units on occupied squares is not possible. If the player drops his/her unit on a friendly unit the airdrop will be considered aborted and could be repeated in the next turn. If the square is occupied by an enemy unit, the airdropped unit is considered lost. Also, if there are enemy air defense units within firing range, these will engage the airdropped unit and any damage the airdropped unit incurs will be considered catastrophic and the unit lost.

Limitations

As we know, a terrain square can contain only at most one unit at a time. It then follows, that airlift and paratroop drop capacities per turn are limited to the number of squares with an airport (or other terrain properties with the "Airlift" property set). Although multiple airports would allow the player to coordinate an air-drop with multiple units, this movement type will always be limited to a few units per turn.