ɐpˈɑːloʊ sˈɪks hæd sˈʌfɚd sˈɛvɹəl mˈeɪdʒɚ pɹˈɑːbləmz dˈʊɹɹɪŋ ɪts ˈeɪpɹəl nˈaɪntiːnhˈʌndɹɪd sˈɪksti ˈeɪt flˈaɪt, ɪŋklˈuːdɪŋ sᵻvˈɪɹ pˈoʊɡoʊ ˌɑːsɪlˈeɪʃən dˈʊɹɹɪŋ ɪts fˈɜːst stˈeɪdʒ, tˈuː sˈɛkəndstˈeɪdʒ ˈɛndʒɪn fˈeɪlɪɹz, ænd ɐ θˈɜːd stˈeɪdʒ ðæt fˈeɪld tə ɹˌiːɪɡnˈaɪt ɪn ˈɔːɹbɪt.
Apollo6 had suffered several major problems during its April 1968 flight, including severe pogo oscillation during its first stage, two second-stage engine failures, and a third stage that failed to reignite in orbit.