By using simultaneous observations of low-altitude energetic electron fluxes from the magnetic electron spectrometer on OV3-3 and equatorial electron fluxes observed by ATS 1 a previously identified strong pitch angle scattering mechanism is shown to be a low-altitude phenomneon only. The relationship between this scattering process and the apparent location of the outer-zone energetic electron boundary as observed by low-altitude polar-orbiting satellites is demonstrated. The process explains observations of rapid electron boundary motions during geomagnetically quiet times. In addition, by assuming that the process also explains the energetic electron spike sometimes seen at the apparent outer-zone cutoff the magnitude of the spike itself is used to determine the high-altitude limit of the rapid-scattering region.