F15C's Landing short of runway

[Jaz_Horus]

Im on day 1 about 8:00 AM and I have noticed that the F 15c's are landing or should I say crashing short of the runway. Is this a fuel problem. I noticed that the waypoints for refueling are at altitude 0. Could this be stopping them from refueling or is that the normal way to set up a mid air refueling stop.