A fire extinguisher is an active fire protection device used to extinguish or control small fires, using an extinguishing agent. Small vehicles may carry extinguishing systems to protect engines and fuel stores from flame.
— Battlelog description
A specialization available for air vehicles, the Extinguisher will put out engine fires and return the vehicle to 37% health, clearing "disabled" status and possibly allowing the vehicle to regenerate the remaining health. After use it takes 25 seconds to recharge. It cannot be used while above 37% health.
This specialization greatly helps aircraft as it can prevent the aircraft from being destroyed which would give the enemy team air superiority. Aircraft are also difficult to repair as they must land first; this is harder with jets than with attack helicopters. Additionally, aircraft are often hijacked or destroyed during repair attempts, or end up in places where the pilot cannot take off successfully.
Extinguisher coupled with Maintenance gives the player's aircraft greater survivability, as the Extinguisher can allow the aircraft to regenerate health after being disabled and Maintenance can regenerate the aircraft's health to full at a greater speed than normal.
Some players may neglect to finish off a disabled air vehicle. Prove them wrong by giving a good burst of the extinguisher and quickly get to a safe location and return to full strength. You might be able to do a surprise attack on that enemy when you return. Furthermore, this is useful to prevent unguided weapons (like Coaxial HMG-equipped tanks) from destroying you.
Also, most players will bail from a disabled vehicle, so you can take an opportunity to enter the vehicle and use the extinguisher to escape to friendly lines and gain an advantage over the enemy team by depriving them of an asset, while keeping it to your team. It is considerably easier to do this with a ground vehicle for obvious reasons, but it is not impossible to steal aircraft. Caution should be advised, as if the previous operator recently used extinguisher, you will have to wait for it to recharge. Also, you are vulnerable to fire, as you are extremely close to being disabled again, and to the vehicle exploding.
The Extinguisher should be applied when you are no longer under enemy fire. Since this specialization only brings vehicle back to 37%, the vehicle might end up being disabled again immediately after using the Extinguisher.
— In-Game Description
— In-Game description
When activated by pressing( , or ) in a vehicle that is disabled, it will extinguish the fire, stopping any further damage to the vehicle and allow the vehicle to recover from the damage.
Unlike its use in Battlefield 3, the fire extinguisher allows a vehicle to regain full mobility following a critical hit. Ground vehicles do not recover armor above the vehicle's disable threshold. Air vehicles retain recovery to 37%, which allows the pilot to endure further damage while retreating. Vehicles can now escape from danger while still having very little armor protection.
Despite the in-game description, armor regeneration does not begin immediately after using Fire Extinguisher. Because Reactive Armor increases the critical hit threshold, there is little benefit to using this upgrade with Fire Extinguisher. The Fire Extinguisher remains unable to break weapon or missile locks, or provide concealment. The vehicle operator must rely entirely on cover and teammate support to prevent armor loss.
A patch late in the game reduced the cooldown from 25 seconds to 4 seconds. This works well for players who will expect firm resistance as the short cool down and the ability to bring the vehicle back from a critical hit allows the driver to make planned escapes more effectively. This coincided with a reduction in the uptime of Active Protection, which made that countermeasure less valuable.
— In-game description
It can be equipped on all customizable vehicles, including cars and helicopters, for the driver position. It can only be used when the vehicle is on fire. For most vehicles this is at 20% (30% for air vehicles). It will quickly clear the disabled state, and regenerate the vehicle's health to 37%, putting out the fire. This gives the vehicle and its occupants an increased chance of survival, and can make for a quick getaway from an enemy attack.