The abbreviation DAT means "delivered at terminal".
This means that the seller must deliver the goods to a specified terminal on the agreed date. The terminal does not have to be an airport building; it could also be a port quay, a container depot or a normal railway station.
DAT is a part of the Incoterms ("International Commercial Terms") and an item of the Rules for any Mode or Modes of Transport contained therein. This includes, but is not limited to, that the Seller bears all risks during carriage and unloading at the terminal.