# SPEED, DISTANCE, AND TIME COMPUTATIONS

SPEED, DISTANCE, AND TIME COMPUTATIONS

- Speed, distance, and time are three interrelated elements. With any two of these elements, you can compute the third (missing) element.
- The computations are
*Speed = Distance / Time**Distance = Speed X Time**Time = Distance / Speed*

- You can use your flight computer to make the above computations.
- Note that in any problem both the speed and distance must be in either SM or NM.
- You can convert SM to NM or vice versa easily as explained in the preceding module.

- The computations are
**Determining Time Required**- If you know the groundspeed and the distance, you can calculate the time. Time equals distance divided by groundspeed.
- EXAMPLE: How much time will it take to fly 120 NM at a groundspeed of 100 kt.?
- Rotate the inner scale so the Index is opposite 100 kt., or “10,” on the outer scale, as shown in the figure.
- Locate 120 NM, or “12,” on the outer scale.
- Under 120 on the outer scale read 72 min. on the inner scale or 1:12 on the hour scale.

- Use your flight computer to solve these practice problems (answers are located below).

__Groundspeed____Distance____Time__a. 80 kt. 300 NM _____ b. 95 kt. 19 NM _____ c. 105 kt. 62 NM _____ d. 120 mph 142 SM _____

- Answers to practice problems
- 225 min. or 3 hr. 45 min.
- 12 min.
- 35.5 min.
- 71 min. or 1 hr. 11 min.

**Determining Distance**- If you know groundspeed and time, you can determine the distance. Distance equals groundspeed multiplied by time.
- EXAMPLE: How far will the airplane fly in 8 min. at a groundspeed of 90 kt.?
- Rotate the inner scale so the Index is opposite 90, as shown in the figure.
- Locate 8 on the inner scale.
- Opposite 8 on the inner scale is 12 NM on the outer scale.

- Use your flight computer to solve these practice problems (answers are located below).

__Groundspeed____Time____Distance__a. 107 kt. 3 hr. 27 min. _____ b. 95 kt. 17 min. _____ c. 105 kt. 43 min. _____ d. 120 mph 1 hr. 24 min. _____

- Answers to practice problems
- 370 NM
- 27 NM
- 75 NM
- 168 SM

**Determining Groundspeed**- If you know the time and distance, you can determine the groundspeed. Groundspeed equals distance divided by time.
- EXAMPLE: What is the groundspeed if the airplane takes 7 min. to go 10.5 NM?
- Rotate the inner scale so that 10.5 on the outer scale is opposite 7 on the inner scale, as shown in the figure.
- Locate the Index on the inner scale and read a groundspeed of 90 kt. on the outer scale.

- Use your flight computer to solve these practice problems (answers are located below).

__Distance____Time____Groundspeed__a. 5.5 NM 3 min. ________ b. 10 NM 6.5 min. ________ c. 15 NM 9 min. ________ d. 5 SM 4 min. ________

- Answers to practice problems
- 110 kt.
- 92 kt.
- 100 kt.
- 75 mph