  The leading contribution to the uncertainties of atmospheric neutrino flux
calculations arise from the cosmic-ray nucleon flux and the production cross
sections of secondary particles in hadron-air interactions. The data-driven
model developed in this work parametrizes particle yields from fixed-target
accelerator data. The propagation of errors from the accelerator data to the
inclusive muon and neutrino flux predictions results in smaller uncertainties
than in previous estimates, and the description of atmospheric flux data is
good. The model is implemented as part of the MCEq package, and hence can be
flexibly employed for theoretical flux error estimation at neutrino telescopes.
