The 'based-on' aspect.

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I read the book, "With Wind to the West" by Jurgen Petschul, which is the real story. The Keller family does not exsist and they made several balloons before they got it right. At one point, as well Peter Streylzk was desperate to get out, even dropping a note at the Chinese Embassy in Berlin asking for help. Also, when they got into West Germany, they were not welcomed with open arms. As with every person that escaped, they were granted automatic West German citizienship, however they were held by the police for a time while their story was being investigated. The family and friends that remained behind were, naturally, punished as well.

As far as anyone knows, the Stasi were not hot on their trail when they made their second, and successful, flight.