Sounds human to me too but I wonder if we've been primed by the headline to recognize it as such. If it had just been posted as "Mystery sound on American Airlines flights", maybe we would have interpreted it differently. This has worked on me before for backmasking and was quite remarkable how different what I heard between when I was primed and when I listened to the track a week later without priming.
the tonal inflections are very human, and in the recording it felt the voice changed a bit after the flight attendant made an announcement, so it's probably live (not necessarily making the sound, but using a soundboard).
