Operation Guide 5242
How does the altimeter work?
Generally, air pressure and temperature decrease as altitude increases. This watch bases its altitude readings 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 |
|
| ||||
3500 m |
| 701 hPa |
|
|
|
|
|
| ||||||
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 |
|
|
| 30.5°F |
|
| |||||||
8000 ft. |
|
|
| About 0.17 inHg per 200 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. |
|
|
|
| ||||||||||
•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 | |||
Source: International Civil Aviation Organization
|
|
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 readings is also affected by temperature. When taking altitude readings, do not subject the watch to temperature changes.
•Do not rely upon this watch for altitude readings 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.
Taking a barometric pressure reading
The Barometer Mode uses a pressure sensor to take barometric pressure readings.
•The differential between two readings is also indicated.
Hand Indicators
z Hour Hand: Indicates the 100s digit value when the pressure unit is hPa, and the 10s digit value when the unit is inHg.
x Minute Hand: Indicates the 10s digit value when the pressure unit is hPa, and the 1s digit value when the unit is inHg.
c Second Hand: Indicates the 1s digit value when the pressure unit is hPa, and the first digit value to the right of the decimal place when the unit is inHg.
v Mode Hand: Points to BAROMETER hPa when the pressure reading is less than 1000 hPa, points to
BAROMETER 1000 when the reading is 1000 hPa or higher, or points to BAROMETER inHg when the unit is inches of mercury.
30 | 30 |
Example: 920 hPa | Example: 25.1 inHg |
To take a barometric pressure reading
1.Enter the Timekeeping Mode.
• For information about changing modes, see “Selecting a Mode”
| (page |
| 2. Press B once. |
| • The v Mode Hand will move to BAROMETER hPa or |
30 | BAROMETER inHg. This indicates the currently selected |
| barometric pressure unit setting. For information about how to |
| change the setting, see “To specify altitude, barometric pressure, |
| and temperature units” (page |
| • The c Second Hand will move to 0 indicating that barometric |
| pressure reading operation has started. The reading result will be |
| displayed within 10 seconds. |
•If the barometric pressure differential was displayed the last time you exited the Barometer Mode, entering the Barometer mode displays the pressure differential.
| Note |
| • This watch takes barometric pressure readings in 1 hPa (0.1 inHg) |
| units. |
| • The barometric pressure measurement range and display range are |
| 260 hPa to 1100 hPa (7.7 inHg to 32.5 inHg). |
| • Whenever a barometric pressure reading is outside the allowable |
30 | measurement range, the hands of the watches will move to the |
| positions below. |
z Hour Hand, x Minute Hand, c Second Hand: 11 o’clock
v Mode Hand: BAROMETER hPa or BAROMETER inHg
Barometric Pressure Differential Indicator
Your watch automatically takes a barometric pressure reading every two hours (at the
Positive differential: Indicates improving weather.
Negative differential: Indicates deteriorating weather.
|
|
Hand Indicators
z Hour Hand: Points to 12 o’clock.
x Minute Hand: Points to 12 o’clock.
c Second Hand: Specifies the barometric pressure differential in the range of ±10 hPa.
v Mode Hand: Points to BAROMETER hPa.
Reading the Barometric Pressure Differential Indicator
Pressure differential is indicated in the range of ±10 hPa, in
•The nearby screen shot, for example, shows what the pointer would indicate when the calculated pressure differential is approximately
•The hPa unit is always used for barometric pressure readings. You also can read the barometric pressure differential in inHg units as shown in the illustration.
Current pressure
inHg values | greater than most | |
recent measured | ||
| ||
hPa values | pressure | |
| ||
| 30 |
c Barometric | Current pressure |
Pressure | less than most |
Differential | recent measured |
Indicator | pressure |
To show and hide barometric pressure differential
1.While a barometric pressure reading is displayed in the Barometer Mode, press C.
•Pressing C while an auto barometric pressure reading is indicated will take a new manual reading and cause the c Second Hand to indicate the differential between the auto reading and the new manual reading.
2.Each press of C at this time will cause the hands to toggle between indication of the barometric pressure reading and the barometric pressure differential.
•The watch maintains the last barometric pressure auto reading in memory. The stored reading is replaced whenever a new auto reading is performed.
Note
•The barometric pressure differential unit is 1 hPa, and the display range is ±10 hPa.
•If the barometric pressure differential is outside the ±10 hPa display range, the c Second Hand will move to 11 o’clock.