A man stole a small aircraft at gunpoint Sunday and flew it over downtown Frankfurt, circling skyscrapers and threatening to crash into the European Central Bank. He landed safely after about two hours and was arrested. The man told a television station he wanted to call attention to Judith Resnik, a U.S. astronaut killed in the 1986 post-launch explosion of the space shuttle Challenger. Military jets chased the stolen, two-seat motorized glider as the man began circling slowly above Frankfurt's banking district. Thousands of people were evacuated from the main railway station, two opera houses and several skyscrapers. Police identified the man as a 31-year-old German student from Darmstadt, a city about 25 miles south of Frankfurt. In radio contact with air traffic controllers, the man threatened to crash into the European Central Bank headquarters unless he was allowed the TV interview as well as a call to Baltimore. He later said he wanted to commit suicide by plunging the plane into the Main River. It was unclear if the man was forced to land, or talked down. Air traffic controllers and a police psychologist had been in contact with him.