The helicopter is a plane unit that can be built in the Airport or an Aircraft carreer. It can garrison up to three infantry units and fires at the same time. The amount of damage dealt depends on the amount of units garrisoned. The units garrisoned inside, however, will not alter the damage or range of the helicopter, meaning a helicopter with three light infantry inside will deal the same amound of damage as a helicopter carrying Three juggernauts. They are amongst the fastest units in the game, beaten only by other fast air vehicles such as Stealth Bombers and Space Fighters. This makes them a more compact, cheaper and more versitile version of Transport Plane as they are cheaper, faster and can attack even with no garrisoned units. They fly lower than the other flying vehicles.
Since the helicopter can enhance its damage with soldiers, it can be used to carry units to not only enhance its damage, but shield the soldiers from harm until is dead/sold. Although, because the helicopter has low health, it should only be used in small attacks and not attacks on a base.
Because the Helicopter is a relatively fast air unit that can garrision infantry, it can be used as a quick way to transport slower infantry such as Juggernauts quickly across both land and water. They can serve to carry infantry units from one plant to the other.
If the player aspires to use them for their damage only, instead of their transportation capailities, garnisoning cheap and expendable units like Light Soldiers.
If they'll be used mainly for transportation and dwift raids, using them with Juggernauts is a better tactic than using it with Heavy Soldiers since the former would require half the helicopters for transportation, leaving more space in the army for stronger planes. Six Juggernauts will only require two helicopters, while four helicopters are needed for the transportation of 12 Heavy Soldiers to match the former's damage output.
Note that if a helicopter is downed with Soldiers still garnisoned inside, all the units will be destroyed. Thus it is advisable to ungarnison all the troops if the helicopter is heavily damaged. Lost Health can be healed using Hospitals.
As long as the player has enough plane population left and is willing to use it for Helicopters, they are practically a better alternative to Transport Plane in all major areas but Health and capacity. However it should also be kept in mind that Helicopters fly lower than any other aerial units, including the Transporter Planes. While this minor detalil may not matter at all in the majority of situations, it means that a helicopter will not be able to drop Soldiers to the top of a hill that a Transport Plane barely reaches, making them unpreferable to Transport Planes on Building military bases on hilltops of certain heights.