It's probably "Ajanouha ihtan!", which means "Everyone under!"
There's a forum thread on GameFAQs about this particular question.
Post #8 by erict1628,
It's "Ajanouha ihtan!", which means "Everyone under!" in Al Bhed.
Cid is telling everyone to get to the Airship because he's going to level Home.
but Post #10 by Fallacia (an Al Bhed expert),
This is actually one bit of Al Bhed I've never been able to fully get. I've never fully agreed with the "everyone under" interpretation. That may have been what was in the script, but the VA's pronunciation changes it a little bit. There's no pronunciation at all of the "uha" for "one" at the end of everyone. Instead, what he's saying is actually much closer to "ajano ihtan," with the spacing making it sound like "Ajanoiht-an." It tripped me up for a long time, because I had thought that he was saying something that sounded more like, "anmanoehk," "ammanoehk," "or amanoeh," all of which are nonsense when translated. With those, you get erlering, ellerying, and eleryin.
I'm willing to believe that it was supposed to have been "everyone under," but instead it comes out as "Every Under" thanks to poor pronunciation of a language that none of the voice actors were actually supposed to have known. The same thing happens when people try to speak other languages for which they haven't developed an ear or just aren't native speakers. Even if the pronunciation isn't entirely too bad, it could still be completely unintelligible to a native speaker thanks to intonation, pausing between syllables, manufactured sounds, muted sounds, and a general sense that the person themselves hasn't created an association for the words they're saying, almost as if they are reading instead of speaking.
There's a same question posted on Yahoo! Chiebukuro (Japanese), with the answer,
Is it the guy who was repeating "Hiasiri hanhemo!" (it's difficult to be heard though)?
In Al Bhed, "Hiasiri hanhemo" means "Evacuate to the basement".
It's spoken like "Hia(siri) han(hemo)".
I think Ultimania (guidebook) has this info. Also it's mentioned on Al Bhed Home's page on Japanese FF Wiki.