It is demonstrated that the simultaneous observations on Viking of upward field-aligned fluxes of energetic ions and electrons of energies in the same range may be due to acceleration in field-aligned electric fields, the ions in an upward directed parallel dc field and the electrons in a downward directed parallel field which is fluctuating but appears as quasi-static for the electrons as long as they are in the acceleration region. Most of the upward accelerated electrons leave the limited acceleration region in an effective half period of the fluctuating field when it points downward. The fluctuating field has only a small effect on the ions. ¿ American Geophysical Union 1988