The range of Sam missile, depends on lot of factors. AAD missile has a range of 40 km against an incoming ballistic Missile. AAD would have a range of 250 km against a slow moving AWACS type of target
The obvious reason is the limitation of radar. By the time the radar detects target ballistic missile, tracks, the ballistic missile, locks into target, allocates the missile launcher, AAD missile is oriented, cleared, armed and fired and AAD missile accelerates, manoeuvres and travels 40 km. In the said time the target ballistic missile my travel 300 km.
Not quite accurate.
This limitation of radar only applies to sea-skimming missiles that take nap of the earth flight. These missiles are harder to detect because of the curvature of the earth but as the maximum speed they can attain is limited to only Mach 4; the time distance ratio is roughly 1:80. So for each one minute you take the missile would have gotten closer by 80km. So you still have plenty of time to react even if you do a late detection.
So basically; hard detection - easy interception.
But with ballistic missiles it's opposite; easy detection - hard interception.
As soon as a ballistic missile gains even a kilometer of altitude it pretty much negates the curvature of earth effect; it's now as visible as the sun. This is why even low powered counter battery radars are so effective...as soon as the projectile no matter it's mortar or artillery appears above the horizon you can pin point it's launch position. US can track a Russian ballistic missile as soon it's fired using its OTH radar. Similarly the ships AESA would be able to track a ballistic missile as soon as it enters it radar range.
Now coming to the time taken in launch...no, things now happen simultaneously instead of sequentially. For example missiles are not oriented and launched...they are launched without orientation, even actual target coordinate are not entered, only a vague direction is given to its INS and the missile is fired. While the missile is accelerating in the general direction, in the mean time actual interception point is calculated and uploaded via the datalink.
In 1970s, it took Sprint missile hardly 15 second from tracking a ballistic missile to intercepting it at an altitude of 30km.
Things happen in a blink of an eye.
