AREA 51 - Like the Blackbird 50 years before it's time. It would not suprise me if they gad Anti gravity at this point
Roswell - I just do not believe that something smart enough for intersteller travel would come all this way and then crash.
But if I wanted to introduce myself I might load up some dead bodies in a old model spaceship and crash it to give the aliens something to think about till a formal intro took place.
Good tinfoil is hard to come by:)
Evidently they did not have their craft configured right to deal with the radar installations we had at the time. They adjusted things and solved that particular problem.
They aren't perfect any more than we are.