Well, the Serbs had agents near Aviano so they knew the takeoff time, airspeed and probable flight path, which undoubtedly helped in terms of positioning radar to defeat the F117’s stealth capability.
Yup. Unbelievable as it sounds, they were ORDERED by the commander in chief himself to take exactly the same path every night.
Positioning radar had very little to do with it. They simple filled the flight path with massive amounts of lead. I'm pretty sure the Russians reimbursed them for the ammo in exchange for access to the crash remains.
Sorta reminds one of LBJ with a map selecting targets every morning. That worked well.