Abstract High-altitude and stratospheric experiments with X-ray emulsion chambers have revealed a tendency for coplanar arrival of the most energetic particles and/or narrow subcascades in cores of extensive air showers. Simulations of the cascade development in the atmosphere based on traditional models of hadron interactions, namely, FANSY 2.0/QGSJ, QGSJET II-04 and SIBYLL 2.3E, have been carried out. In addition, the FANSY 2.0/2D model based on the hypothesis of a connection between coplanari