Exposed at different altitudes (stratospheric, mountain...), X-ray emulsion chambers have given evidence for some unusual phenomena such as coplanar and halo events. These phenomena which are observed in the energy range of the Large Hadron Collider (LHC) are hard to explain with only standard physics. To understand these remarkable cosmic ray events, we have performed a set of Monte Carlo calculations using the CORSIKA code in combination with different hadronic interaction models (HDPM, QGSJET and DPMJET). The main features of these events are investigated and their physical relevancy is discussed.