Please explain air coverage

[macegee]

While trying to understand why my land based planes have no impact on naval air combat, I did a quick test to see how the air coverage works. And now I'm more puzzled with the air system in HOI4... Please, explain this to me. Would be great if @podcat or another dev can comment.

Example 1.

USA, West Coast. 3x groups of 100x P-40, spread over the region, give me 21.1 AS score with 14% coverage.

Example 2.

Same area. 1x group of 300x P-40, placed on a single airfield. 27.8 AS score, 16% coverage.

Why, oh why? Example 1 should obviously give more coverage.

 

[Executor]

You want the airbase to be located as close to the center of the region you're operating in as possible, otherwise they'll be taking large penalties to mission efficiency from lack of range.

 

[Alex_brunius]

Yeah it's based on amount of airplanes / size of airzone * mission efficiency ( which in turn as pointed out above is based on distance from airbase to center of region )

Think of it this way, the planes in the airbases on the edges of the airzone have more of their total area of coverage "wasted" outside the airzone.