Instrument Rating Checkride Practice Test

How do you convert feet per NM to feet per minute?

1. Climb Gradient x Groundspeed in knots

2. Groundspeed/60 x Climb Gradient in Feet Per NM

3. Groundspeed x Climb Gradient in Feet Per NM

4. Feet per NM divided by Groundspeed

The correct answer is: Groundspeed/60 x Climb Gradient in Feet Per NM

To convert feet per nautical mile (NM) to feet per minute, it's important to understand the relationship between distance, speed, and time. The conversion involves the speed of the aircraft (groundspeed) and the climb gradient, which indicates how many feet the aircraft climbs over a nautical mile of distance. The correct method involves taking the groundspeed in knots and adjusting for time. Since 1 knot equals 1 nautical mile per hour, dividing the groundspeed (in knots) by 60 gives you the number of nautical miles the aircraft covers in one minute. To find the number of feet climbed per minute, this value is then multiplied by the climb gradient expressed in feet per nautical mile. This process effectively provides the total vertical distance climbed per minute, linking horizontal speed to vertical climb rate directly. In contrast, other approaches do not accurately relate these measurements or incorporate the necessary adjustments for time or unit consistency. This makes the selected answer the most accurate method for making the conversion from feet per NM to feet per minute.