Hi,
My idea is simple: alien UFO has a flag "stealth", that makes this UFO invisible for detectors when in air. Or in general this is detectionModifier other then size and altitude.
This is actual possible to create something similar without this flag. Size is very_small, altitude is very low, speed is like 100000, and trajectory is to land on the ground for long time. But there is always a chance that player would somehow by luck intercept this UFO, which will ruin the afford. Actually by design there should be no interception fight at all. Problem is that if UFO is hard to detect in the air it is also hard to detect on the ground at the same time.
So i created a UFO that is very hard to be detected, is very fast and lands on the ground ASAP, stays on ground for long time. Battlescape does not contains normal UFO instead of this it contains special mapBlocks like Man In Black Base. This could give us missions like "rescue pilot" or "defense factory" without need to code anything else.
What do you think about it ?