In order to understand why there should be the NS-500 SAM, it's important to understand the idea of a layered air defense. That simply means that you have a mix of air defense systems. Some for short range, others for extreme long range. In PS2, both flak and MANPADS are short-range air defense systems (and paltry ones at that). There's really nothing effective for engaging enemy aircraft at long distance. What the NS-500 SAM does is provide a balanced solution to that problem, complete with vulnerabilities that can be exploited by organized pilots and squads. The NS-500 SAM is a surface-to-air missile system that is mounted on the back of a Sunderer. It has mainly two modes. The first is the "road mode", or when it is moving from area to area. The second is the "fire mode", or when it is ready to fire. Characteristics of the NS-500 SAM System Advantages Long-range missiles- can achieve lock at almost render ranges. Fool-proof missiles- missiles cannot be fooled by flares and can navigate around most terrain. High-damaging missiles- two missiles can set a Liberator to burning. Disadvantages Must deploy to fire- needs to spend 45 seconds (less with upgrades) to deploy and undeploy. High resource cost- takes up the Sunderer's 400 vehicle resources, making it the second most expensive unit in the game (right after MBTs). More expensive than Liberators or Galaxies, that's for sure. Highly visible- when deployed or undeploying it is autospotted for all units within lock range. Additionally enemy aircraft which have been locked-on by the NS-500 SAM system will have a special tone that indicates it is a NS-500 SAM. Completely defenseless- lacks any of the armaments available to the Sunderer, meaning that apart from running people over it has no offensive anti-ground capabilities. Low ammunition count- only has a total of 6 missiles, for 3 launches before it has to rearm. Long reloads- the time between missile salvos is very long at 30 seconds (less with upgrades). Long lock time- the time to achieve missile lock is 8 seconds (more if the target has Stealth). However lock time significantly decreases the closer the target gets. Unable to AMS or resupply- due to missile storage, the vehicle cannot act as an AMS Sunderer and does not have an infantry resupply terminal. Still can carry 12 soldiers though, to negate the "your vehicle shouldn't be able to blow up my 1/3 Liberator" argument. Practical Usage First off the NS-500 SAM needs planning and preparation. Given the long set-up time, it needs to be in place well-before enemy aircraft have entered the area. Even once set-up, the NS-500 SAM needs to be picky about which targets it fires at. Shooting at ESFs might mean an easy kill, but that means that the NS-500 SAM would be vulnerable to the next air target that came along, like a Liberator or another ESF. But against enemy Liberators or Galaxies the NS-500 SAM would be highly effective. No more dread when watching an enemy Galaxy as enemy Gal drops are now preventable. No more Liberators smirking as they shoot from afar or retreat after sustaining light damage. So with the right preparation, defenses, and logistical support the NS-500 SAM fills in a gap of air defenses that needs to be covered. Vulnerabilities There are of course many counters to the NS-500 SAM that can be utilized by organized enemy forces. Ground units are perhaps the easiest. Sending in 2 AT Harassers to knock down a NS-500 SAM would give Harassers a more significant role. Not only would the NS-500 SAM be completely defenseless against enemy ground units, it wouldn't be able to undeploy quickly enough to avoid death. A literal sitting duck. Even air units would have some counter to the NS-500 SAM if they can't be bothered to coordinate with ground units. Mobbing the NS-500 SAM with ESFs would be a pretty viable option, as the NS-500 SAM shoots so slowly that it wouldn't be able to react to all the threats. Deterrence Capability Given the high visibility of both the NS-500 SAM and its slow missile lock, pilots should be well aware when they are flying into dangerous airspace. The NS-500 SAM is a true deterrence... unless pilots leave the area quickly or have a plan to destroy the NS-500 SAM, they will have a very high probability of dying themselves. Most pilots think that a deterrence simply means that the unit cannot easily destroy their aircraft... but this is not the correct definition of a deterrence. Instead, a deterrence is something that will result in a high probability of death if they do not immediately stop what they're doing. That's how deterrence works (see "nuclear deterrence"). Conclusion The NS-500 SAM adds a unique vehicle which takes skill and organization to use and to counter. While powerful, its severe limitations mean that it must work closely with other air defense units (like a Burster MAX or Skyguard) in order to effectively combat enemy air. Additionally it must rely heavily on other ground units and resupply units to protect it and keep it armed.