A test particle treatment is used to investigate some of the details of the pickup cometary ions observed at comet Halley. The effects of the large-scale magnetic and motional electric fields, as described by an MHD model of the comet, produce the characteristic V shape seen in Giotto observations in simulated energy-time spectrograms. It is demonstrated that scattering produced by the addition of magnetic field fluctuations can obscure the tendency of the large-scale field to deflect energetic ions picked up in the outer coma from the tail axis. The fact that the V is so clearly observed in the Giotto spectrogram thus suggests that although scattering must be invoked to explain the isotropic pitch angle distributions and highest energy ions, it does not have a major effect on the overall pickup ion spectrum. ¿ American Geophysical Union 1988