  In the sub-TeV regime, the most widely used hadronic interaction models
disagree significantly in their predictions of particle spectra from cosmic ray
induced air showers. We investigate the nature and impact of model
uncertainties, focussing on air shower primaries with energies around the
transition between high and low energy hadronic interaction models, where the
dissimilarities are largest and which constitute the bulk of the interactions
in air showers.
