The speed at which an aircraft descends vertically in altitude over a predetermined period of time is referred to as the rate of descent. Numerous factors, such as the aircraft’s configuration, angle of attack, thrust setting, and atmospheric conditions, affect the rate of descent. When an aircraft descends vertically to a lower altitude, the rate of descent formula is applied. Since the drag is greater than the thrust in this instance, the net force (thrust-drag) is negative, indicating a negative vertical speed. The formula for the rate of descent () of an aircraft can be expressed as:
Where:
- is the thrust produced by the aircraft’s engines (N),
- is the total drag experienced by the aircraft (in N),
- is the weight of the aircraft (in N).