When a gunner comes across a target of opportunity, he may not be able to take advantage of it.
The cooldown time of the NVS is 2.5 to 3.5 minutes. Seeker cooldown takes about 10 seconds. Once the BCU is activated, the gunner has a maximum of 4 minutes to engage the target before the BCU is spent. Vehicles crossing the street or moving between buildings (flank shot) are exposed for about 10 to 15 seconds, meaning the gunner may not have enough time to lock-on to the target and fire.