"Endeavour"s last Orbiter Major Modification period began in December 2003 and ended on October 6, 2005. During this time, "Endeavour" received major hardware upgrades, including a new, multi-functional, electronic display system, often referred to as a glass cockpit, and an advanced GPS receiver, along with safety upgrades recommended by the "Columbia" Accident Investigation Board (CAIB) for the shuttle's return to flight following the loss of "Columbia" during reentry on 1 February 2003.