In the screenplay page 114, the way Ava communicates - which is alluded to in an earlier conversation she has with Caleb on how she can detect microexpressions - is detailed well:
The image echoes the POV views from the computer/cell-phone cameras in
the opening moments of the film.
Facial recognition vectors flutter around the PILOT’S face. And when he opens his mouth to speak, we don’t hear words. We hear pulses of monotone noise. Low pitch. Speech as pure pattern recognition. This is how AVA sees us. And hears us.
It feels completely alien.
EXT. MEADOW - DAY 126
AVA and the PILOT finish talking. We are too distant to hear their conversation. But whatever is said, a few beats later, the PILOT goes the
helicopter and opens the passenger door, to allow AVA to
Then he goes back to the PILOT’S door. Gets in.
And the rotor blades start to turn.
I like the AI pilot theory too, but it's likely that she just manipulated the pilot into taking her away. It's a pity that this scene didn't make it into the movie.
BTW and editing re apology for zombie thread revival: I am sorry that this is awakening the dead. Just thought the screenplay would be of interest to any fan who hasn't already gotten their hands on it.
Edit: Wow. Thanks for my first badge ever - you guys rock! :)