Question:
Can four construction units build a 12-capacity airfield in the same hex at the same time? Each unit builds a 3- capacity airfield.
Answer:
No, Rule 14A1 states that you can’t build a permanent airfield in a hex that contains a permanent airfield. This includes a permanent airfield under construction, so once you start build a permanent airfield in a hex you cannot start building others there. Also note that augmenting a permanent airfield is a different concept than building a permanent airfield even though both use very similar procedures. For clarity, when the rule says “A construction unit may augment (increase) the capacity of an existing permanent airfield”, “existing” is meant to mean that the airfield has completed construction.
Also note that this answer does mean you cannot build two or more forts in the same hex at the same time.
Source:
TEM 53