Operation X is an special stage available in Ace Combat X: Skies of Deception. It is unlocked by completing all of the game's missions. The game's equivalent to "The Gauntlet" from Ace Combat Zero: The Belkan War, Operation X has players engage AI-controlled versions of the game's fictional aircraft, such as the XFA-24A Apalis and the YR-302 Fregata.
A non-canon mission, the player's mission in Operation X is to fight through formations of all of Ace Combat X's original aircraft, except for the Fenrir. As you progress through the mission, enemies will begin spawning all around your position, often overwhelming you in higher difficulties. Once the X-02 wave is destroyed, you will be engaged by a squadron of four ADF-01 FALKEN aircraft, the main targets of the mission, two of which are armed with TLS laser pods. Destroying the FALKEN formation will finish the mission.
In Normal mode and higher, once a single ADF-01 remains, two unidentified aircraft will engage the battle from both sides of the map, the aircraft in question being the aces ADF-01 "Z.O.E." and XFA-27 "Scarface" from Ace Combat 2, their respective aircraft bearing their original paintjobs (simple red and white with red trim, respectively.) Killing both pilots will unlock their respective aircraft's Special paint scheme.
- 2x XFA-24A Apalis
- 2x YR-302 Fregata
- 2x XR-45 Cariburn
- 2x YR-99 Forneus
- 2x XFA-27
- 2x X-02 Wyvern
- 4x ADF-01A/F FALKEN (TGT)
- 1x XFA-27 "Scarface 1"
- 1x ADF-01A/F Falken "Z.O.E."
- First playthrough: ADF-01; all Leasath 1 paint schemes for all original aircraft except FALKEN and Fenrir if S-ranked.
- Operation X marks the first occasion where an enemy-controlled ADF-01 is able to use the TLS. Unlike the player, however, the TLS-wielding FALKENs will often hit with quick swipes that deal low to medium damage, instead of outright killing the player.
- All the enemy aircraft are the ones that can be tuned in the Hanger for the player.