More than 100 people, many of them Iranian journalists, were killed this week when a military transport plane that was carrying them crashed into a building in Tehran. The reporters were on their way to observe a naval exercise in the Persian Gulf. The plane had just taken off when the pilot reported technical trouble and tried to double back to the airport. Witnesses said the aircraft, a U.S.-built C-130, was on fire before it hit the building. Irans C-130s have chronic maintenance problems. They were bought before the 1979 Islamic revolution, and subsequent U.S. sanctions made it hard to get parts.