A flight recorder is a recorder placed in an aircraft to help with investigating an aircraft accident or incident. For this reason, they have to be capable of surviving extremely rough treatment. They are usually built to withstand an impact of 3600 g and temperatures of over 1,000 °C (as required by EUROCAE ED-112), because a powerful impact followed by a very hot fire is what usually happens in a plane crash. There are two types of protected Flight Recorder, Flight data recorder (FDR) and Cockpit voice recorder (CVR). In some cases, the two recorders may be combined in a single FDR/CVR unit. The first combined flight recorder was invented by Australian scientist, David Warren.