After the crash of '' Osoaviakhim-1 '' in January 1934 '' USSR-1 '' was retrofitted with a gondola parachute and a new gas envelope . June 26 , 1935 it flew again as '' '' ' USSR-1 Bis '' ' '' . The balloon reached 16,000 meters where an accidental release of hydrogen , probably caused by a faulty valve , forced it into an unexpected descent . After expending all available ballast , two crewmembers bailed out on personal parachutes at low altitudes ; flight commander stayed on board and managed to perform a soft landing on a crippled aircraft
Osoaviakhim-1
Osoaviakhim-1
USSR-1