The September 29, 1989, cosmic ray ground level enhancement had a comp
lex intensity-time profile with two distinct peaks observed at some ne
utron monitors, The event was detected by surface and some underground
muon telescopes indicating the presence of particles up to similar to
30 GV. We have modeled the response of neutron monitors and surface m
uon telescopes at the times of both intensity peaks and during the dec
ay phase, We have determined particle rigidity spectra and pitch angle
distributions centered on apparent arrival directions. Some evidence
of bidirectional flow is present during the second peak, This may be d
ue to backscattering of particles from beyond Earth. There was a high
degree of scattering from all directions resulting in a significant is
otropic component. Spectra derived from ground level responses are con
sistent with satellite observations, The spectrum between a few MeV an
d a few tens of GeV is consistent with shock acceleration.