Salvage teams at the site of Iran’s worst plane crash in six years have recovered the Caspian Airlines Tupolev TU 154’s two flight recorders. But the force of the impact and the subsequent fireball from a near-full load of fuel badly-damaged the ‘black boxes’, which had spewed out their recording tape. A third flight recorder is still missing. Recovering any vital data as to the causes of the crash could prove difficult.Eye witnesses say the plane’s tail was on fire before it went down, and the last messages from the cockpit were that the plane had suffered a technical failure and the pilot was attempting a crash landing. This is the third Russian-made TU 154 to crash in Iran since 2002. The Iranians have been under sanctions for nearly 30 years from the USA, stopping purchase of Boeings, spare parts, or any other aircraft using American engines.