Recently I read UFOs in Reality: Programmed Aerospace Monitors (Google book preview link) by T.R. Dutton. Dutton is an aerospace engineer who applied his knowledge of orbital mechanics and astronomy toward UFO sightings. He discovered that a majority follow predictable locations, times, and directions.
Here's an article on Dutton: http://www.daviddarling.info/encyclo...s_Dutton1.html
In short, he claims that these sighted crafts behave as though they are scout ships dropped from a mothership in orbit. These scouts (some like drones, some occupied) descend to the ground while the mothership continues along a set circular orbit around the planet. There are only a limited number of such orbits, as if they were pre-established.
The scout ships stay put or wander nearby until the mothership passes overhead again, then take off to rendezvous. This limits their window of departure depending on their location. Dutton figured out what these orbital tracks were, and therefore could predict the place and time of greatest potential for a sighting.
What I got from this book is that rather than using some arbitrary coordinate system for navigation, these alien ships use such predetermined orbital tracks along with geographic landmarks, sun position, and the position of the planets for their interplanetary and interstellar navigation.
This pattern was hidden beneath the statistical data and was never obvious, never openly admitted by aliens to their abductees and contactees, yet the pattern seems to exist. So I think the pattern is real, and this would support the idea that some aliens -- even if they are time travelers, even if they are hyper-dimensional, even if they aren't fully here in our physical reality -- do perform interstellar travel and can come here from outside the solar system, contrary to some theories that they are earthbound beings pretending otherwise.