The rate-of-climb indicator shows the rate at which an aircraft is climbing or descending. The case of a climb indicator is airtight except for a small connection through a restricted passage to the static line. Changes in atmospheric pressure move the operating mechanism that displays the rate of change. This change occurs only when the aircraft is ascending or descending. When the aircraft ceases to climb or dive, the air pressure into the metering units equalizes and the pointer returns to zero.
