Аннотация:The complexity of the development of extensive air showers makes it extremely difficult to study
the nature and the sources of cosmic rays at ultra-high energies. The largest uncertainties are
related to the modelling of hadronic interactions in the air shower cascade. The sensitivity to
the theoretical description is maximised when measurements in the forward phase-space at accelerators
are combined with measurements based on cosmic ray data. So far, this method has
never been applied to constrain interaction models. Here, we outline a strategy to find an optimal
global description of the underlying physics, ultimately leading to a consistent understanding of
astrophysics as well as hadronic interaction physics at ultra-high energies.