Check Airplane Descent Calculator Pro Suppose you are flying at 10.000 feet and need to descend to 2.000 feet. Where do you begin the descent? Airplane Descent Calculator Lite allows you to calculate the distance in which the plane should begin the descent to get the target altitude, for a specific descent rate (vertical speed) and ground speed (horizontal speed). Many times during an aircraft flight, true ground speed differs from precomputed ground speed, so, during the flight is necessary