A flight data recorder from an unknown public transport aircraft is seen in private aviation museum in the village of Zruc, near Plzen January 28, 2015. Flight recorders or ?black boxes?, used in investigations of aviation catastrophes since the mid-20th century, have developed considerably over the years. While older recorders contained spools of magnetic tape, modern devices use crash-survivable digital chips. There have been increasing calls for commercial planes to be fitted with ejectable recorders that separate from the tail during a crash, technology already in use by military aircraft. The ?deployable black boxes? combine voice and data recordings and emit a distress signal to a global search and rescue satellite system. Picture taken January 28, 2015 REUTERS/David W Cerny