Citizen C390 Specifications download pdf (Page 25)

4948

Answer. Align “21” on the outer scale with the SPEED INDEX (

) on the inner scale.

then, “40” on the inner scale corresponds to “14” on the outer scale. Thus, the

air distance of the flight is 140 nautical miles.

4) Rate of fuel consumption

Example: Obtain the rate of fuel consumption (gallons / hour) when the flight time is 30

minutes and the fuel consumption is 120 gallons.

Answer. Align “12” on the outer scale with “30” on the inner scale. Then, the SPEED

INDEX (

) on the inner scale corresponds to “24” on the outer scale. Thus, the

fuel consumption is 240 gallons per hour.

5) Fuel consumption

Example: Obtain the fuel consumption required for a flight when the vate of fuel

consumption is 250 gallons per hour and the flight time is 6 hours.

Answer. Align “25” on the outer scale with the SPEED INDEX (

) on the inner scale.

Then, “6:00” on the inner scale (time scale) corresponds to “15” on the outer

scale. Thus, the fuel consumption is 1,500 gallons.

6) Estimated flight time

Example: Obtain the estimated flight time when the vate of fuel consumption is 220

gallons per hour and the aircraft has 550 gallons of fuel.

Answer. Align “22” on the outer scale with the SPEED INDEX (

) on the inner scale.

Then, “55” on the outer scale corresponds to “2:30” on the inner scale (time

scale), Thus, the estimated flight time is 2 hours and 30 minutes.

7) Difference in altitude

The difference in altitude can be obtained from the rate of descent and the descent time.

Example: Obtain the difference in altitude when an aircraft continues descending for 23

minutes at a rate of 250 feet per minute.

16. Using the Register Ring

The bezel design may vary depending on the model.

[Calculation function]

Note the following points when using this

function. Use the calculation function of this

watch only as a guide.These scales do not

indicate the position of the decimal point.

A. Navlgational calculation

1) Time required

Example: Obtain the time required fo the fight of an aircraft at 180 knots for 450 nautical

miles.

Answer. Align “18” on the outer scale with the SPEED INDEX (

) on the inner scale.

Then, “45” on the outer scale corresponds to “2:30” on the inner scale (time

scale). Thus, the time required for the flight is 2 hours and 30 minutes.

2) Knots (air speed)

Example: Obtain the knots (air speed) for 240 nautical miles with a flight time of 1 hour

and 20 minutes.

Answer. Align “24” on the outer scale with “1:20” on the inner scale (time scale). Then,

the SPEED INDEX (

) on the inner scale corresponds to “18” on the outer

scale. Thus, the air speed for the flight is 180 knots.

3) Flight diatance

Example: Obtain the air distance when the air speed is 210 knots and the flight time is 40

minutes.

Speed index

Outer scale

(distance scale)

Inner scale

(Time acale)

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Citizen C390 Specifications Page 25

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