Fox-3 indicates the launch of an active radar-guided missile, such as AIM-120 AMRAAM.
First of all, you need to enter A/A mode and select Fox-3 missile. You can do it, pressing Weapon Select Switch - Select AIM-120, or pressing A/A mode button and selecting active radar-guided missile, pressing F button.
It’s an optional mode, using when you haven’t enough time to lock target properly and seconds decide everything. Place your target in circle and launch missile.
Be careful, it’s mode also called “lazzy dog” mode, because missile lock a first founded target, no matter enemy or friendly.
After a target is locked, you will see additional information about it.
You can launch your missile after you can see “IN LAR” label above a target. If it starts to blink, you have better chances to hit a target