Advancements in distributed avionics processing imposes significant data communications requirements on next-generation aircraft. Higher performance, improved fault tolerance, and increased connectivity are needed to support such applications as the Electronic Library System, Onboard Maintenance System, and Cabin Management System. In response, the Onboard Local Area Network (OLAN) project was initiated in the ARINC Databus Subcommittee. OLAN is a networking profile based on the International Standards Organization Fiber Distributed Data Interface LAN standard. OLAN characteristics specify a subset of capabilities, and exclude any options not appropriate for use in aircraft. In this paper, the history of OLAN work is traced, the OLAN architecture is introduced, and specific OLAN protocol profiles are summarized. Finally, challenges confronting the OLAN are examined.