The Bush family arrived by motorcade at Joint Base Andrews, a US military facility in Maryland.
There was a departure ceremony at the base, including a 21-gun salute.
Bush Sr's casket was loaded on to the presidential jet Air Force One, re-purposed for the occasion as Special Air Mission 41.
A band played Hail to the Chief and the Czech composer Antonin Dvorak's Goin' Home.
The Bush family are flying to Texas, where the former president will lie in overnight repose at St Martin’s Episcopal Church in the city of Houston.
His final resting place will be next to wife, Barbara Bush, on the family plot at the grounds of his presidential library on the campus of Texas A&M University in the city of College Station.
He'll be buried there tomorrow.