[This file is mirrored in both the FlightGear and SimGear packages.] You *must* have the development components of OpenAL installed on your system to build FlightGear!" You can get a copy here: http://www.openal.org Build notes: The OpenAL developers do not make "versioned" releases so we recommend that you pull the latest version via anonymous CVS (follow the instructions at the OpenAL web site) and build/install that.