Ripley: Micro changes in air density, my ass.
Parker: It's a robot. Ash is a god damn robot.
Ripley: Ash, that transmission... Mother's deciphered part of it. It doesn't look like an S.O.S.
Ash: What is it, then?
Ripley: Well, I... It looks like a warning. I'm gonna go out after them.
Ash: What's the point? I mean by the, the time it takes to get there, you'll... They'll know if it's a warning or not, yes?
Chosen answer: Because Ripley would warn the other crew members about the Special Order, namely that the company's mission was to collect the alien (to use as a biological weapon) and that the crew was expendable. The company assigned Ash to carry out the plan, and being a robot, his only intent is to follow their orders.
raywest