We propose an expression for the O+ atomic oxygen ion velocity distribution in the upper part of the auroral F layer when the ions are subjected to an intense convection electric field. We assume that this layer is made up of neutral O atomic oxygen and atomic O+ ions. In order to obtain the O+ ion velocity distribution function, we use the Boltzmann equation with a modified relaxation collision term. The evolution of this function is governed by the convection electric ionospheric fields and by the ion-neutral and ion-ion collisions. To investigate these two collision effects, we use a new phenomenological and self-consistent model. We obtain the non-Maxwellian ion distribution function as a linear combination of a torodial anisotropic contribution and of a Maxwellian isotropic contribution. The coefficients of this linear combination depend on the ion-neutral and ion-ion collision frequencies vii and vin. We self-consistently calculate the expressions and values of these two frequencies. We note that the vii/&ngr;in ratio increases when the electric field increases and that this ratio is greater in our model than for the Maxwellian steady state. At 500 km the O+ ion velocity distribution function is almost isotropic, but at 300 km the distribution is anisotropic when the magnitude of the ionospheric electric field is very large. ¿ American Geophysical Union 1992