Embodiments are described for a machine and process that include a computer code specially programmed on a non-transitory medium to change an altitude, of an aircraft that remains certified for flight by a pilot, such that the aircraft contains an altimeter having a fixed altimeter setting. The computer code may be configured to: receive an assigned altitude and a barometric pressure for a location of the aircraft; determine a differential between a height above mean sea level indicated on an altimeter using the new barometric pressure for the location of the aircraft and a height above mean sea level indicated on an altimeter based upon the fixed altimeter setting; modify, based upon the differential, a flight planned altitude for the aircraft, to create a pilotless altitude; send the pilotless altitude to the aircraft; and fly the aircraft at the assigned altitude via commanding flight at the pilotless altitude.