There are multiple defense mechanisms that are provided as unlocks for air vehicles in Battlefield 3. My friend and I were debating when to actually deploy ECM vs Flares. Personally, I have my own system with my gunner to evade missiles / getting locked but he was assuring me that my practice was wrong.
His version: Deploying ECM when missiles are fired and tracking to the target.
[I told him my version:]
My version: Deploying ECM after about 2 seconds of 'getting painted' or getting locked on. While ECM is being deployed, I either try to asses where the threat is coming from or bug out. If they are able to gain another lock on my helicopter, I coordinate with my gunner for when to deploy his flares. Most of the time, the missile misses us and my ECM jammer is reloaded. In theory, this would keep us up for a long time [ as long as we don't get killed by a SOFlam / Javelin combo or guided shell].
When is the best time to deploy ECM Jammer ?
Side Note: I have already seen this post, and they are not the same question.