Is this on PS4?
Actually closer to 900m/s. For anyone to close a distance of 2700m in 5 seconds, the speed difference needs to be 540m/s between the two. That would leave the Krait at 927m/s (540 + 387), which just isn't possible.
If the numbers are correct, it's a scripter/hacker for sure. With packhounds hitting the target, it is however more likely that a) they have drag experimental, which slows down the Asp in FA ON quite a lot (= zero pips to eng), and b) it took longer than 5 seconds to close the gap / the gap was smaller than 2.7km.
what is the best defense in this situation?
I have pushed my krait to 530M/s, not sure what sort of upgrade though so It may go s bit further. And it is possible he has got a full array of lightweight engineer mods to push it further