This is a difficult question to answer without more facts. However, he will not automatically be sent to the Federal Bureau of Prisons. A Petition to Revoke/Modify Supervised Release will be filed with the federal sentencing court, and a hearing will be scheduled. At that time, your father has the option of contesting the violation (DUI and Fleeing), or he may stipulate that he has indeed violated the terms of his supervised release, and be sentenced. US Sentencing Guidelines Chapter 7 (ussc.gov) covers recommended sentences on supervised release violations, called "policy statements." I was recently involved in one of the cases that ended in 90 days home confinement. Don't assume the worst yet.