Gambit, are there missiles out there that maintain a slower speed at lower altitudes (to remain undetected !) till they reach a said-distance from the target and hence maneuver themselves accordingly but as soon as that distance is reached they speed up at an exponentially higher rate to hit the target ! A little like utilizing the element of surprise till the last moment possible and positioning yourself accordingly and finally striking before your enemy can respond back !
Somewhat redundant. Slow speed does not mean low detectability. Low altitude does. When a missile is below most radar horizon, at the point where the missile's own sensor -- radar or IR or both -- can detect the target, it would be too late for the target precisely because of that low altitude.
When a missile's sensor detect the target at the earliest opportunity, that point in time and in spatial perspective is called 'horizon break'...
Attention North Korea: Aegis Missile Intercept a Success | Aero-News Network
Raytheon Integrated Defense Systems' Kauai-based TPS-X (Transportable Surveillance X-Band) radar tracked the target missile from launch and also tracked the SM-3 from horizon break through target intercept.
This is a two-way street, usually if a defender's radar can detect the missile, most likely the missile's own radar detects the target, so 'horizon break' works both ways.
So for the example above, the sentence '
tracked the SM-3 from horizon break through target intercept.' means the tracking system detected the SM-3 at the moment the missile became visible over the horizon and tracked the missile's flight all the way to intercept. That is what 'horizon break' mean.
Visual distance from one's point to horizon is about 25 km in clear weather.
Horizon calculator - radar and visual
You can use that calculator to estimate the 'horizon break' distance depending on radar antenna height but basically, the higher the defender's radar height, the longer that 'horizon break' distance, and the more the response time. Ground level and the 'horizon break' distance is in the mid 20s km. Against a subsonic threat, the defense will have only a few seconds. Against a supersonic threat, really none at all.
