CPL Navigation Practice Exam

Indicated altitude refers to the altitude reading shown on the altimeter, which is essentially derived from the atmospheric pressure. This reading is influenced by the International Standard Atmosphere (ISA) values, which provide a standardized set of conditions for atmospheric pressure at different altitudes. The altimeter is calibrated to these ISA conditions, meaning that it assumes that the atmosphere is behaving as defined by the ISA model when providing altitude readings. If the atmospheric pressure is different from the standard atmospheric pressure defined by ISA, the indicated altitude may not accurately reflect the true altitude. Hence, indicated altitude is very much dependent on the underlying air pressure and temperature conditions at the time, demonstrating why the option about the influence of ISA values is the correct understanding of indicated altitude.