Distraught family members grieve at the site of an Iranian air crash in which 168 have been killed.A Caspian Airlines flight came down about 15 minutes after taking off from an airport in Tehran. The Russian-built Tupolev aircraft, bound for the Armenian capital, crashed into farmland near the city of Qazvin. Reports indicate the plane caught fire after suffering a technical problem. This is the worst air crash in Iran for six years. Air safety experts say Iran has had a string of crashes in the past few decades, many involving Russian-made aircraft. Observers say US sanctions against Iran have prevented it from buying new aircraft or spares from the West. The passenger list included 151 adults, two children and 15 crew.