- "...rebel ships use Gatling close-in gun. They'll destroy your missiles."
- ― Varona 1
CIWS (close-in weapon system), pronounced "sea-whiz", is a defensive weapon system utilized by naval vessels to protect them from enemy missiles or aircraft. They are typically deployed on Aegis ships and battle cruisers in the Ace Combat series, but have been used on aircraft carriers and even aircraft as well.
CIWS are typically gun-based and supported by on-board radar systems. They are capable of inflicting heavy damage to aircraft that fly too close and can neutralize most incoming enemy projectiles (missiles, bombs, etc.).
However, CIWS are notably ineffective at targeting numerous projectiles at once. Some CIWS also take time to recharge after tracking a certain number of targets.
CIWS appears briefly in Ace Combat 5: The Unsung War dialogue and cutscenes. One ship is heard using Phalanx CIWS in "Narrow Margin", and the OFS Kestrel attempted to use a CIWS barrage against submarine-launched missiles prior to its sinking. In the latter case, the Kestrel could not destroy all of the missiles, two of which caused the carrier's destruction.
The first Co-op Battle mission in Ace Combat 6: Fires of Liberation features the Kraken, an aircraft carrier that uses CIWS to block the players' attacks. The players must first defeat all other enemies and then destroy the CIWS with their machine guns to make the carrier vulnerable.
In Ace Combat: Joint Assault, Milosz Sulejmani flies a GAF-1 Varcolac with a second machine gun that acts as a CIWS to shoot down incoming missiles. The player must use their own machine guns to disable the system.
The Naval Fleet Assault mode in Ace Combat Infinity featured Aegis ships that use CIWS to intercept incoming weapons. However, they were less accurate against unguided weapons or close-range attacks and, like Assault Horizon, could be overwhelmed by consecutive attacks. In addition, both the QFA-44 Camilla and the SOLG program satellites were protected by laser-based CIWS that operated in the same fashion.
CIWS appears frequently in Ace Combat 7: Skies Unknown on Erusean warships, notably Aegis vessels in Mission 11, Fleet Destruction and SP Mission 2, Anchorhead Raid. CIWS are also seen on the North and West platforms in Fleet Destruction and on Aegis Ashore command centers in Mission 15, Battle for Farbanti and SP Mission 2, Anchorhead Raid. The Alicorn also carries multiple CIWS units. They are capable of shooting down missiles flying towards the ship they are on, however, low-flying Long-Range Air-to-Ship Missile attacks can get past them. The CIWS can damage the player's aircraft, but do similar damage as anti-air gunfire. AD Tanks also possess CIWS or a similar system, capable of shooting and destroying missiles targeting them. The AD Tank CIWS can be gotten past by missiles easier than ship and land-based CIWS.