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This article provides details regarding how air combat functions. For advice on how to use airpower, visit the Airforce strategy guide. Air combat works similar to land combat, strength and org are reduced for the battling parties.
There are two modifiers for attack and defense. They are calculated from several values. Each of these values is given as +x% or -x%. The value is first converted into a multiplier.
m = 1 + x / 100%
So +30% gives a multiplier of 1.3. The multipliers are multiplied and after each step, the result is rounded down to 3 digits (See example).
The possible influences are given in their order of appearance. The order of appearance is the same as the order of multiplication.
Please help: The night, radar and territorial modifiers might not be in the right spot.
The experience of an air wing gives a modifier to attack and defense.
Each skill point of the leader will give +5% bonus. Bonus will be always 0% when the leader's rank is too low to command the stack.
Any plane that is not bomber or transport on intercept mission get a +20% modifier to attack only (Bonus defined in defines.lua, variable: INTERCEPT_ATTACK_BONUS = 0.2).
Any plane that is not bomber or transport on air superiority mission get a +20% modifier to Defence only. (Bonus defined in defines.lua, variable: AIR_SUP_DEFEND_BONUS = 0.2). This bonus is shown in battle tooltip as Intercept.
Several doctrines from Air doctrine technology grant a bonus called mission efficiency.
- Ground Attack Tactics
- Interception Tactics (only bonus to interception, no bonuses for air superiority)
- Interdiction Tactics
If radio is researched, there is a +10% modifier per level of radio strange. All units in vanilla hoi3 have radio strange = 1 so bonus will be always +10%.
The stacking penalty used for aircraft creates a normal distribution penalty whereby the maximum effectiveness of aircraft stacks is five or six. Any aircraft beyond that number become increasingly less effective. TFH update: Stacking penalties cannot reduce efficiency below 20%. The cap limits them to an 80% stacking penalty, which leaves 20% efficiency. If you throw enough planes at the problem (like 20), you can actually overcome the stacking penalty and do respectable damage. There is no longer a 0% efficiency situation with 10 or more planes.
|# of Wings|| Penalty (Air-to-Air)
| Effective # of Planes
| Penalty (Air-to-Air)
| Effective # of Planes |
Remember modifiers are multiplied. A +30% experience modifiers does not shift the equilibrium to 8 planes. Each air unit beyond the 6th will always net a weaker force. The only exception are CAGs (carrier air groups), which only have a -5% stacking penalty.
Stacking penalty for bombing missions is 10% even for the first wing so optimal number of wings is five, but as a consequence it is easier to overcome the stacking penalty with massive wings:
|# of Wings|| Penalty (Bombing)
| Effective # of Planes
| Penalty (Bombing)
| Effective # of Planes |
Nearby radar gives a bonus to air-to-air and air-to-ground (!) combat. 
RB = RL * 0,05 * (1+RCI/100) * 100%
RB - radar bonus RCI - radar combat impact modifier in % RL - highest radar level from province where battle occurs and all neighbour provinces
This is the bonus for the first wing in stack. Second wing will get RB/20, third wing will get RB/500. For other wings it is always zero, even when radar combat impact modifier is like 10^6.
Radar give bonus in all neighbour provinces. Bonuses from many many radars are not cumulative only the highest level radar will give bonus.
Radar will add bonus to all allied planes in its bonus range.
Summary of radar bonuses (for first wing):
|Radar level||+0% RCI||+5% RCI||+10% RCI||+20% RCI|
This modifier, introduced in Semper Fi, gives a bonus to combat efficiency for Axis and Soviet units fighting for their cores. Territorial pride is a relatively fixed modifier, which can only be increased by three Strategic Effects.
Night gives a -50% modifiers to attack. This modifier is modified by two factors:
- night flyer leader leader trait adds +10%.
- each point of plane air detection will add +1% (increased by Small/Medium/Large Air search radar technologies)
For example Interceptors and Multi-role fighters (base air detection = 1) with Night Flyer leader and level 3 air radar (1943 tech) will have final night modifier = -36%. Rocket Interceptor have base air detection = 6 so with Night Flyer leader, modifier is -34%.
This example shows how the modifiers presented in the screenshot are combined into the final result. Starting with a neutral multiplier of 1, each effect gets multiplied into the intermediate result (IR), which is rounded down to three digits before the next step.
Explanation: After mission efficiency multiplier has been applied, the rounded result is 1.965. Now with radio, 1.965 * 1.1 = 2.1615, with is rounded down to 2.161 before the next multiplication.
The final result of 1.9 coincides well with the 190.00% in the screenshot.
Planes always repair at midnight GMT, even if they are in combat or in the air.