  We review the calculation of the prompt lepton flux, produced in the
atmosphere by the semileptonic decay of charmed particles. We describe side by
side the intermediary ingredients used by different authors, which include not
only the charm production model, but also other atmospheric particle showering
parameters. After evaluating separately the relevance of each single
ingredient, we analyze the effect of different combinations over the final
result. We highlight the impact of the prompt lepton flux calculation upon
high-energy neutrino telescopes.
