The role of charm at ultrahigh energies

Experimental data on cosmic ray cascades with enlarged attenuation lengths (Tien-Shan effect) are discussed in terms of charmed particles production. The obtained values of the charm hadron production cross-section at high energies are presented and confronted with recent accelerator data. The seeming absence of GZK-cutoff is ascribed to the delay of evolution of the cascades with charm in the atmosphere. The important role of large cross section of charm hadron production in the development of inclined showers in the atmosphere at ultrahigh energies is shown.