Ok, hows this for reason. The predator ship from avp holds about 4 of the original ships from PREDATOR 1. Now, when the Predalien emerges, It reaks havic on the AVP ship. Systems become critical and the predators are forced to abandon the mother ship, which would most likly mean escaping in the Predator 1 ship. The Predalien sneaks aboard (like in Alien 1 on Ripleys ship. The brothers said "back to roots") The ship becomes damaged and the closest planet is Earth to attempt to crash land. This to me seems logical