We have analyzed the geomagnetic transmission of solar energetic Fe ions at ∼200–600 MeV/nuc during the great solar energetic particle (SEP) events of 1989 September–October. By comparing fluences from the Chicago charged‐particle telescope onIMP‐8 in interplanetary space and from NRL’s Heavy Ions in Space (HIIS) experiment aboardLDEFin low‐Earth orbit, we obtain a mean ionic charge ⟨Q⟩=14.2±1.4. This result is significantly lower than ⟨Q⟩ observed at ∼1 MeV/nuc in impulsive events, and suggests that neither acceleration at the flare site nor flare‐heated plasma significantly contributes to the high‐energy Fe ions we observe. But it agrees well with the ⟨Q⟩ observed in gradual SEP events at lower energies, demonstrating that acceleration by CME‐driven shocks is the primary SEP production mechanism in gradual events even at these very high energies. ©1996 American Institute of Physics.