Vertical speed conversions
Aircraft climb and descent performance is commonly expressed in feet per minute, while engineering or metric references may use feet per second or meters per second. The value can be converted without changing the underlying climb or descent rate.
Feet per minute to feet per second
Divide feet per minute by 60. A climb rate of 600 FPM equals 10 feet per second. To go the other direction, multiply feet per second by 60.
Feet per minute to meters per second
One foot equals 0.3048 meter and one minute equals 60 seconds. Therefore 1 FPM is about 0.00508 m/s. A 1,000 FPM climb is about 5.08 m/s.
Vertical speed is not climb gradient
FPM describes altitude change per unit time. Climb gradient describes altitude gain per horizontal distance, such as feet per nautical mile. The two are connected by groundspeed, so changing groundspeed can change the FPM required to meet the same gradient.
Descent rates use the same units
A 500 FPM descent has the same magnitude as a 500 FPM climb but the vertical direction is downward. Some displays show negative values for descent while others show the rate without a sign.
Three-degree paths
A common descent-planning shortcut relates groundspeed to a target FPM for a roughly three-degree path. That calculation is separate from simply converting units.
Check performance units
POH climb performance may be listed as FPM, while an obstacle requirement may be ft/NM. Do not compare the numbers directly until they have been put into compatible terms.
Related PilotDesk guides
Climb gradient · 3° descent rate · Flight path angle