Airbase Terrain Improvement


Aug 27, 2016
Dallas, TX
This mod adds the "Airbase" Terrain Improvement, allowing you to station aircraft in places other than cities and aircraft carriers.



Based completely on WHoward's "Improvement - Airbases" mod:

This version is modified so the custom DLL is no longer required. A few other small adjustments to meet the requirements of a different mod I'm working on, which needs the capabilities provided in this mod.

Original artwork provided by (who else???) Danrell.


Airbases Summary:

The Airbase is a special Tile Improvement that allows you to station aircraft away from Cities or Aircraft Carriers. They become available at the discovery of Flight, and allow stationing up to 3 Units (Fighters, Bombers, and Missiles). An advanced version of the Airfield becomes available at the discovery of Radar. This `improved` Improvement allows up to 5 Units.

Airbases may be constructed in your own territory or in unowned Desert, Grass, Plains, Snow, and Tundra Tiles. Airbases may not be built in adjacent Tiles.

Airbases do not increase a hex`s productivity or provide access to a Resource. Instead, an Airbase permits stationing of aircraft, and also improves a hex`s defensive bonus by 25%. However, they do not provide a defensive bonus to Units in enemy territory.

You may use another Civilization`s Airbases if you are on the same team or if you have a Declaration of Friendship in place. If a DoF is subsequently cancelled, e.g. you Denounce a Civ where you have Aircaft using one of their Airfields, then those Aircraft may remain in that Airfield, but when they move, they will not be allowed to return. If you have Aircraft in another Civ`s Airfields and then declare war on that Civ, those aircraft will be destroyed.

upload_2018-12-14_8-31-10.jpeg upload_2018-12-14_8-31-30.jpeg upload_2018-12-14_8-31-45.jpeg upload_2018-12-14_8-32-1.jpeg upload_2018-12-18_10-42-34.jpeg upload_2018-12-14_8-32-31.jpeg upload_2018-12-14_8-32-46.jpeg

Mod seems stable, but please let me know if you see anything that needs adjusting. Thanks!

Please Note: this mod replaces the UnitFlagManager UI, so it will be incompatible with any other mod that also replaces that UI (which is more than a few....)
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Other mod? Not sure. We have a pretty good version of the World at War base mod working with VP (

I think this mod should work fine under VP as well. I think the biggest question is if VP changes the "Time" settings on how long it takes workers to make improvements, this mod (which uses "normal" settings for these Timings) might be out of balance. But it should actually work.

If you test it, let me know. Thanks!
@Padre - I've seen the AI use them in a few test games, but I didn't look much further.

There is a place to put "flavors" in for the Tile Improvements table, but this mod didn't add any - the table is actually empty, so no other game system uses these flavors. I'm working on a mod that incorporates this mod, and adding flavors for all the new TI's. Will keep an eye out to see if that improves how well AI uses them, or if it's an obsolete artifact left over from an abandoned design element.

If you're seeing good/bad usage, please let me know. Thanks!

EDIT: after making a bunch of changes, including adding improvement "flavors", during a lot of long test games, I'm no longer seeing AI use these airfields. They may be doing so off map, but my confidence level they use these fields is shrinking quickly... :undecide:
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Everyone please note - I've found a BUG in the mod!

Although you can rebase aircraft to a airfield in another civ's territory, they might disappear each turn.

Aircraft will survive if you have an 'open borders' agreement with the other civ, or if they are on the same team as you.

Still experimenting with an alternative, but this just may not work. Will update the mod when I get to the end of this road. Sorry about the confusion!
Update - new version is out, fixing the bugs mentioned in the previous post.

Changes made to improve how the mod handles air units in airfields located in tiles not belonging to the player.

Instead of a DoF to station planes in a foreign airfield, you now need an Open Borders agreement.

Be careful - if you have planes in a foreign airfield after an Open Borders expires, they disappear....

Stationing planes in a City State's airfield is acceptable if you are their ally, and if some other Civ displaces you as their ally, your planes can remain at the airfield, but no new planes may station there. When the planes leave, they cannot return.

Additionally, improvement "flavors" were added, in the hope the AI would better understand how to use this improvement. After several long test games, my confidence level that the AI 'understands' airfields is plummeting, unfortunately...


There is a small graphics bug that applies to AI unit flags when they enter a city. For some reason, a small black circle appears to the side of the flag. I made no changes to the replacement UnitFlagManager UI, so suspect the problem was in there before.

Still researching this problem, but at least the main issue with non-tile-owned airbase usage has been fixed.
Just a check - is anyone seeing this behavior when an AI land unit moves into a city??

EDIT: Update - This may be a non-issue. I completely removed EUI from my machine and the error disappeared.
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If the initial version of the mod won't work for you - usually because of a conflict with another mod that also replaces the UnitFlagManager UI (which is more than a few), I have developed a different version of this mod that doesn't replace the UI.

It uses a "land carrier" unit, and works better in some cases than the original.

Airbases Terrain Improvement - Unit Based Summary:

The Airbase is a special Tile Improvement that allows you to station aircraft away from Cities or Aircraft Carriers. This mod differs from the 'Airbase Terrain Improvement' mod in that this mod uses a 'Land Carrier' - which is an actual unit, like the aircraft Carrier. It is immobile, has differing unit capacities, and behaves exactly like other units in the game.

This mod also differs from the other Airbase Terrain Improvement mod in that it does not need to replace the UnitFlagManager UI. This will make it much more compatible with a wide variety of mods that also need to change that UI.

The choice of which mod to use will depend on what other mods you combine with this mod, but one thing is certain: Do NOT use both of these Airbase Terrain Improvement mods together!

There are 3 different 'airbase' terrain improvements your Workers can build:

1. Tactical Airstrip (Flight): Stations 2 air units. Strength: 20 (defensive only).

2. Strategic Airfield (Radar): Stations 5 air units. Strength: 40 (defensive only). +25% Defensive Bonus

3. Theater Airbase (Rocketry): Stations 8 air units. Strength: 60 (defensive only). +33% Defensive Bonus

Air units that may use these airfields are typically Triplanes, Great War Bombers, Fighters, Bombers, and Jet Fighters in the basic game. For additional (mod) units, any unit that uses the 'SpecialCargo' element set to 'SPECIALUNIT_FIGHTER' can use these airfields. Stealth Bombers may not.

Airbases may be constructed in Desert, Grass, Plains, Snow, and Tundra Tiles. They may be built in tiles you own, unowned tiles, and even in tiles belonging to different civs, if you have an Open Borders agreement with them.

Airbases do not increase a hex`s productivity or provide access to a Resource. If the airbase has a defensive bonus by 25%, it will not be provided to Units in enemy territory.

Download Link:

The AI uses this new mod much more - as I'm not sure the AI uses the initial version at all.

Which mod you choose to use is up to you, but whatever you do - don't use both mods together!
Screenshots of the "Unit-based Airfield Terrain Improvements":

upload_2018-12-21_17-59-12.jpeg upload_2018-12-21_17-59-25.jpeg upload_2018-12-21_17-59-39.jpeg upload_2018-12-21_17-59-48.jpeg upload_2018-12-21_17-59-59.jpeg upload_2018-12-21_18-0-12.jpeg upload_2018-12-21_18-0-40.jpeg upload_2018-12-21_18-0-53.jpeg upload_2018-12-21_18-1-7.jpeg upload_2018-12-21_18-1-21.jpeg

Please note: these are early screenshots, and a couple of changes were made after they were snapped. The Combat Strength of these 3 airbase units were nerfed quite lower. Also, the "keyboard combination" for the builds moved from "S" to "G".
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More screenshots:

upload_2018-12-21_18-1-50.jpeg upload_2018-12-21_18-2-2.jpeg upload_2018-12-21_18-2-13.jpeg

Please note: some changes were made after these pix were snapped. Basically, the mod now attempts to "rebase" aircraft if you delete an airfield TI (usually by building a different TI on top of the airfield). It will look through all your cities and if it finds a space, it will teleport the aircraft to that city, not caring about the distance. If all your cities are completely filled with aircraft, then it will destroy the planes it cannot rebase.

Yes, I know this could be exploited - e.g. you have aircraft in the distant part of the map and want to move them instantly to the capital... But I think more often than not, you'd want the opposite to be true... ;)
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Hello - the 'Airfield Terrain Improvement - Unit-Based' mod was updated to put in minor corrections and to improve the artwork.

Am not 100% sure, but believe these 2 versions will be the "official" BETA baseline versions. No changes expected.
Hi, great stuff!
I am able to build the airbase (outside my borders), but I cant find a way to rebase a bomber to it. The airbase should be well within its range...
Im using civ5 with all dlc and such on a macintosh. Help greatly appreciated
@Samurai - it's probably the MAC causing the conflict. I'm sorry, but I really don't know a thing about getting mods to work on Mac, and no way of developing/testing one.

@elotar - I haven't published this mod on Steam. I did include the unit-based airfield in the 'World at War - Modern Terrain Improvements' companion mod:

Although a companion mod to WAW, it can be played without the main WAW mod.
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