Is this true?
No, it's not true. Atta went to Afghanistan in 2000 for training. One of his friends - Mossediq?- is on trial in Germany for convering for Atta and his associates while they went to Afghanistan for training. But they may already have been Al Qaeda or Al Qaeda sympathizers before taking that trip.
NATIONAL COMMISSION ON TERRORIST ATTACKS UPON THE UNITED STATES
Outline of the 9/11 Plot
between November and December of 1999, Atta, Jarrah, Shehhi, and Binalshibh went to Afghanistan, traveling separately
Binalshibh, Atta, and Jarrah met with Bin Ladin’s deputy, Mohamed Atef, who directed them to return to Germany and enroll in flight training. Atta was chosen as the emir, or leader, of the mission. He met with Bin Ladin to discuss the targets: the World Trade Center, which represented the U.S. economy; the Pentagon, a symbol of the U.S. military; and the U.S. Capitol, the perceived source of U.S. policy in support of Israel. The White House was also on the list, as Bin Ladin considered it a political symbol and wanted to attack it as well. KSM and Binalshibh have both stated that, in early 2000, Shehhi, Atta, and Binalshibh met with KSM in Karachi for training that included learning about life in the United States and how to read airline schedules.
By early March 2000, all four new al Qaeda recruits were back in Germany. They began researching flight schools in Europe, but quickly found that training in the United States would be cheaper and faster. Atta, Shehhi, and Jarrah obtained U.S. visas, but Binalshibh—the sole Yemeni in the group—was rejected repeatedly. In the spring of 2000, Atta, Shehhi, and Jarrah prepared to travel to the United States to begin flight training. Binalshibh would remain behind and help coordinate the operation, serving as a link between KSM and Atta.
While Jarrah took these personal trips, Atta traveled to Germany for an early January 2001 meeting with Ramzi Binalshibh. Atta reported that the pilots had completed their training and were awaiting further instruction from al Qaeda. After the meeting, Atta returned to Florida and Binalshibh headed to Afghanistan to brief the al Qaeda leadership. As soon as Atta returned to Florida, Shehhi took his foreign trip, an unexplained eight-day sojourn to Casablanca.
http://tinyurl.com/cn834