Operation Guide 3258

How Total Ascent/Descent Values Are Updated

620 m

Session end point

Session start point

320 m

120 m

20 m

0 m

The total ascent and total descent values produced by an Altimeter Mode measurement session during the example climb illustrated above are calculated as follows.

Total Ascent: q (300 m) + e (620 m) = 920 m

Total Descent: w (320 m) + r (500 m) = 820 m

•Entering the Altimeter Mode starts a new altitude auto measurement session, but it does not reset the current ASC (ASC-1and ASC-2) and DSC (DSC-1and DSC-2) values or change them in any way. This means that the starting ASC and DSC values for a new Altimeter Mode auto measurement session are the values that currently are in memory. Each time you complete an Altimeter Mode auto measurement session by returning to the Timekeeping Mode, the total ascent value of the current session (920 meters in the above example) is added to the session’s starting ASC value. Also, the total descent value of the current auto measurement session (–820 meters in the above example) is added to the session’s starting DSC value.

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•Note that any change in elevation when ascending that is less than 15 meters (49 feet) is not added to the total ascent value for the current Altimeter Mode auto measurement session. Also, any change in elevation when descending that is less than –15 meters (–49 feet) is not added to the total descent value for the current Altimeter Mode auto measurement session.

Note

•The high altitude, low altitude, total ascent, and total descent values are retained in memory when you exit the Altimeter Mode. To clear values, perform the procedure under “To clear the contents of a specific memory area” (page E-76).

Using Auto Save Values

The watch maintains two independent sets of auto save values as shown below.

Set 1

Set 2

High Altitude (MAX-1)

High Altitude (MAX-2)

Low Altitude (MIN-1)

Low Altitude (MIN-2)

Total Ascent (ASC-1)

Total Ascent (ASC-2)

Total Descent (DSC-1)

Total Descent (DSC-2)

The values in Set 1 and Set 2 can be cleared independently of each other. This means you can use them to keep track of daily and cumulative data as described in the example below.

Example: Keeping track of data on a three-day climb

Day 1

Clear both Set 1 and Set 2, and start your Day 1 climb.

At the end of the day, both sets of auto save values contain the same data (MAX-1= MAX-2, MIN-1= MIN-2, etc.).

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Day 2

Clear only Set 1, and start your Day 2 climb. At the end of the day, the values in Set 1 (MAX-1, MIN-1, ASC-1, DSC-1) will show the results of Day 2 only. In Set 2, MAX-2and MIN-2will show the high altitude and low altitude reached over the two-day span. ASC-2will show the total ascent for the two days (Day 1 + Day 2) and DSC-2will show the total descent for the two days.

Day 3

Clear only Set 1, and start your Day 3 climb. At the end of the day, the values in Set 1 will show the results of Day 3 only. In Set 2, MAX-2and MIN-2will show the high altitude and low altitude reached over the three-day span. ASC-2will show the total ascent for the three days (Day 1 + Day 2 + Day 3) and DSC-2will show the total descent for the three days.

•For details about clearing altitude data, see “To clear the contents of a specific memory area” (page E-76).

How does the altimeter work?

Generally, air pressure and temperature decrease as altitude increases. This watch bases its altitude measurements on International Standard Atmosphere (ISA) values stipulated by the International Civil Aviation Organization (ICAO). These values define relationships between altitude, air pressure, and temperature.

Altitude

 

Air Pressure

 

Temperature

4000 m

 

 

 

 

 

616 hPa

 

About 8 hPa per 100 m

 

–11°C

 

3500 m

 

701 hPa

 

 

 

 

–4.5°C

 

 

3000 m

 

 

 

 

 

About 9 hPa per 100 m

 

 

 

 

 

 

 

 

 

 

 

About 6.5°C

2500 m

 

 

 

 

 

 

 

 

795 hPa

 

 

 

 

2°C per 1000 m

2000 m

 

 

 

 

About 10 hPa per 100 m

 

1500 m

 

899 hPa

 

About 11 hPa per 100 m

 

8.5°C

 

 

1000 m

 

 

 

500 m

1013 hPa

 

About 12 hPa per 100 m

 

15°C

 

0 m

 

 

 

 

 

14000 ft.

19.03 inHg

 

 

 

16.2°F

 

12000 ft.

 

 

About 0.15 inHg per 200 ft.

 

10000 ft.

22.23 inHg

 

About 0.17 inHg per 200 ft.

 

30.5°F

 

 

8000 ft.

 

 

 

 

About 3.6°F

6000 ft.

25.84 inHg

 

About 0.192 inHg per 200 ft.

44.7°F

per 1000 ft.

4000 ft.

 

 

2000 ft.

29.92 inHg

 

About 0.21 inHg per 200 ft.

59.0°F

 

0 ft.

 

 

 

 

Source: International Civil Aviation Organization

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•Note that the following conditions will prevent you from obtaining accurate readings: When air pressure changes because of changes in the weather

Extreme temperature changes

When the watch itself is subjected to strong impact

There are two standard methods of expressing altitude: Absolute altitude and relative altitude. Absolute altitude expresses an absolute height above sea level. Relative altitude expresses the difference between the height of two different places.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Height of building 130 m

 

Rooftop at an altitude of

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(relative altitude)

 

230 m above sea level

 

 

 

 

 

 

 

 

 

 

 

 

 

(absolute altitude)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sea Level

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Altimeter Precautions

•This watch estimates altitude based on air pressure. This means that altitude readings for the same location may vary if air pressure changes.

•The semiconductor pressure sensor used by the watch for altitude measurements is also affected by temperature. When taking altitude measurements, do not subject the watch to temperature changes.

•Do not rely upon this watch for altitude measurements or perform button operations while sky diving, hang gliding, or paragliding, while riding a gyrocopter, glider, or any other aircraft, or while engaging in any other activity where there is the chance of sudden altitude changes.

•Do not use this watch for measuring altitude in applications that demand professional or industrial level precision.

•Remember that the air inside of a commercial aircraft is pressurized. Because of this, the readings produced by this watch will not match the altitude readings announced or indicated by the flight crew.

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Specifying Temperature, Barometric Pressure, and Altitude Units

Use the procedure below to specify the temperature, barometric pressure, and altitude units to be used in the Barometer/Thermometer Mode and the Altimeter Mode.

Important!

When TYO (Tokyo) is selected as the Home City, the altitude unit is set automatically to meters (m), the barometric pressure unit to hectopascals (hPa), and the temperature unit to Celsius (°C). These settings cannot be changed.

To specify temperature, barometric pressure, and altitude units

1. In the Timekeeping Mode, hold down E until SET Hold appears on the display and then the city code starts to flash.

2.Press D as many times as necessary until SET appears on the display.

•See the sequence in step 2 of the procedure under “To change the current time and date settings manually” (page E-32) for information about how to scroll through setting screens.

3. Perform the operations below to specify the units you want.

To specify this unit:

Press this key:

To toggle between these settings:

 

 

 

Altitude

A

m (meters) and ft (feet)

 

 

 

Barometric Pressure

B

hPa (hectopascals) and inHg (inches of mercury)

 

 

 

Temperature

C

°C (Celsius) and °F (Fahrenheit)

 

 

 

4.After all of the settings are the way you want, press E to exit the setting screen.

• To return to the screen in step 1, press E again.

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