ECM Jammer

ECM Jammer is an electronic countermeasure designed to deceive radar, sonar or other systems such as infrared or laser detection.

Battlefield 3
"Electronic countermeasures including chaff launchers and deceptive transmitters prevent your aircraft from being locked on by enemy weapon systems for a short time when activated"

- Battlelog Description The ECM Jammer is a specialization for pilots of air vehicles. When deployed the ECM prevents enemies from acquiring weapon lock. This is in contrast to IR Flares, which are designed to dispel heat-seeking missiles.

The ECM Jammer hides you from enemy radar while it's active, so you will disappear from enemy air radars for example. This might fool enemy pilots, that you bailed out or crashed. When in a jet, you might encounter enemy fighter who has air radar. If you both have it, fights can get tedious, since neither one wants to break off of trying to get behind the enemy. ECM can be used in such situations, and this might again fool the enemy, and he might head off, allowing you to get behind him.

The ECM lasts for five seconds, and requires 10 seconds before it can be reactivated. Since recharge time is counted from when the jammer is first activated, this leaves a minimum exposure time of 5 seconds between uses.

In attack helicopters with a good gunner, a good defensive strategy is for the gunner to deploy flares, and the pilot to use the ECM to go take cover behind a hill, building or mountain until the gunner's flares recharge.

Confusion over actual effects
Due to numerous issues, there is much confusion about how the ECM Jammer actually works. Various players (notably "Luetin" ) have conducted tests to assess its capabilities.

Many players believe that the ECM Jammer can deflect incoming missiles under certain conditions (i.e. "you must perform evasive maneuvers", "the missile must pass through the chaff cloud"), but the game makes no mention of this ability.

ECM Jammer can deflect incoming missiles most of the time when in helicopters, most notably in the attack choppers. This works quite well when hovering, and deploying ECM when you hear "Missiles lauched" - warning tone. This is not 100%, so missiles might hit you regardless. It often depends on distance between you and enemy who lauched the missile.

On jets however, ECM doesn't work well when it comes to deflecting missiles. They most likely hit even if one tries to evade them, while lauching ECM. So it's recommended to use them as intented while in jets; Preventing missiles from being lauched, rather than deflecting them.