"Foreign Plane Bonuses" is an event-only mechanic where most foreign planes (not from the IJN/IJA) get various damage bonuses.

This mechanic is exclusive to "European Events", since the Summer 2021 Event.
This mechanic used to be called the "Plane Matrix", as the bonus worked in a matrix configuration in its two firsts occurrences.

Generalities

Event maps taking place in the European theater may be concerned by this mechanic. If present, "foreign planes", aka planes from European nations or the USA will provide various damage bonuses.

Those bonuses are arbitrary, and are of the same nature regardless of the plane type, meaning that not only bombers but also fighters and recons will provide those bonuses.
Bonuses are grouped into "groups", where all planes from a given group provide the same bonus.
- Few planes are also placed in more than one group.
The "European planes" list is arbitrary, it notably includes planes like the Japanese Stuka, but excludes ones like the SB2C-5.
- Refer to the current event bonus lists to see the affected planes (see here for the lists from past events).

If a ship equips planes with bonuses, it will gain the given group bonus (it may only be applicable on certain nodes).
- If several planes from different groups are equipped, then the ship will gain the bonuses from each group.
  - This also applies to planes in more than one group, giving by itself several bonuses.
- If several planes from a same group are equipped, then the bonus from this group is only applied once.
In the case of LBAS, each of the bases is counted separately.
Bonuses given to ships and LBAS are not the same.

Those bonuses work for all ships/LBAS and for all attack types, including LBAS, jet assault, airstrikes, air/surface shellings, and night attacks.

The bonus is still counted even if a plane is in a 0-plane slot.

Past Event Bonuses

This mechanic was used in all events with maps being located in the European theater since the Summer 2021 Event

It is notably absent on maps of those events that did not take place in Europe.
It is adjusted and updated at each iteration.

Summer 2021 Event

Maps: E-1, E-2, E-3

Bonus table (MO):

Historical Aircraft Bonuses			Map-wide	W	Z
Group A	Swordfish TBF TBM-3D Re.2001 G Kai Skua Re.2001 CB Kai		1.1x	1.2x	1.25x
Group A	Installation DB	FM-2 F4U-1D Ju 87C Kai Ju 87C Kai Ni (w/ KMX) Ju 87C Kai Ni (w/ KMX/Skilled)	1.1x	1.2x	1.25x
Group B	Carrier-based	Swordfish Mk.II (Skilled) Swordfish Mk.III (Skilled) Barracuda Mk.II Barracuda Mk.III	1.15x	1.3x	1.35x
Group B	Land-based	SM.79 SM.79 bis Do 217 E-5 + Hs293 Initial Model Do 217 K-2 + Fritz-X	1.15x	1.3x	1.35x
Stacking multiple planes from the same group on a CV does not give higher bonus e.g. A + A = 1.1 B + B = 1.15 A + B = 1.265

Bonus matrix (EA):

Historical Aircraft Bonuses
?????	Land-based	SM.79 SM.79 bis Do 217 E-5 + Hs293 Initial Model Do 217 K-2 + Fritz-X

Historical Aircraft Bonuses
		Aircraft Groups			Bonuses
		A	B	C	Map-wide	Nodes I/O/Z2	Node Z3
Aircraft Groups	1		Skua Re.2001 CB Kai Ju 87C Kai Ju 87C Kai Ni (w/ KMX) Ju 87C Kai Ni (w/ KMX/Skilled)		1x	1x	1x
	2	Swordfish TBF TBM-3D FM-2 F4U-1D F4F-3 F4F-4 F6F-3 F6F-3N F6F-5	Bf 109T Kai Fw 190T Kai Fw 190 A-5 Kai (Skilled)		1.05x	1.1x	1.1x
	3	Re.2001 G Kai Swordfish Mk.II (Skilled) FR-1 Fireball	Re.2001 OR Kai Fulmar		1.08x	1.12x	1.15x
	4	Swordfish Mk.III (Skilled) Barracuda Mk.II Barracuda Mk.III	Re.2005 Kai	Corsair Mk.II Corsair Mk.II (Ace) Seafire Mk.III Kai Fulmar (Reconnaissance Fighter/Skilled)	1.08x	1.12x	1.15x
Bonuses	Map-wide	1x	1.08x	1.15x
	Nodes I/O/Z2	1x	1.08x	1.15x
	Node Z2 (Post Phase 3)	1x	1.4x	1.15x
	Node Z3	1x	1.1x	1.18x
tl;dr For max bonus, take one plane from C4 + one plane each from B3 and A2/B2 or B2 and A3/B3 e.g. C4 + B3 + B2 or C4 + B3 + A2 or C4 + B2 + A3 How to calculate bonus Multiply all eligible letters together, then multiply all eligible numbers together e.g. A1 + A1 = A * 1 A1 + B1 = A * B * 1 A1 + B2 = A * B * 1 * 2

Summer 2022 Event

Maps: E-3, E-4, E-5, E-6

Bonus matrix:

Aircraft Damage Bonuses
		Aircraft Groups [1] [2]			Multipliers (Ships and Land-bases) [3]
		A	B	C	Mapwide	Node W	Nodes Y, Z
Aircraft Groups	1	-	PBY-5A Catalina LBAS	Spitfire Mk.I LBAS Spitfire Mk.V LBAS Spitfire Mk.IX (Skilled) LBAS	-	-	-
	2	B-25 LBAS Swordfish TBF TBM-3D TBM-3W+3S SBD SBD-5 SB2C-3 FM-2 F4U-1D F4F-3 F4F-4 F6F-3 F6F-5 F6F-3N F6F-5N XF5U	Fw 190 D-9 LBAS Bf 109T Kai Fw 190T Kai Fw 190 A-5 Kai (Skilled)		1.02x	1.0404x	1.0506x
	3	SM.79 LBAS SM.79 bis LBAS Swordfish Mk.II (Skilled) Re.2001 G Kai Re.2001 CB Kai Skua Ju 87C Kai Ju 87C Kai Ni (w/ KMX) Ju 87C Kai Ni (w/ KMX/Skilled) FR-1 Fireball	Re.2001 OR Kai Fulmar	F4U-4 AU-1 F4U-2 Night Corsair	1.04x	1.0608x	1.0712x
	4	Do 217 E-5 + Hs293 Initial Model LBAS SM.79 bis (Skilled) LBAS Swordfish Mk.III (Skilled) Barracuda Mk.II Barracuda Mk.III	Do 217 K-2 + Fritz-X LBAS Re.2005 Kai	Mosquito FB Mk.VI LBAS Mosquito PR Mk.IV LBAS Mosquito TR Mk.33 F4U-7 Seafire Mk.III Kai Corsair Mk.II Corsair Mk.II (Ace) Fulmar (Reconnaissance Fighter/Skilled)	1.06x	1.0812x	1.0918x
LBAS only Multipliers (Mapwide)		-	1.06x	1.08x

In this event, the SB2C-5 did not get any bonuses, as the devs misattributed its bonus to the FR-1 Fireball which received 2 groups bonus in return (this was due to a bug/typo with their game ID being 421 & 422).