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Operation Guide 5114 5214
E-64
Auto Save Values
While the altitude auto measurement method is being used (page E-55), the watch automatically stores
high altitude (
HI
), low altitude (
LO
), cumulative ascent (
ASC
), and cumulative descent (
DSC
) values.
• These values are checked and updated automatically by the watch as altitude auto measurements are
taken.
How high altitude and low altitude values are updated
While the watch is in the Altimeter Mode, altitude readings are taken automatically at the interval specifi ed
by the altitude auto measurement method (page E-55). With each reading, the watch compares the
current reading against the
HI
and
LO
values. It will replace the
HI
value if the current reading is greater
than
HI
, or the
LO
value if the current reading is less than
LO
.
How Cumulative Ascent/Descent Values Are Updated
Session start point
20 m
0 m
120 m
320 m
620 m
Session end point
E-65
The total Cumulative Ascent and Cumulative Descent values produced by an Altimeter Mode
measurement session during the example climb illustrated above are calculated as follows.
Cumulative Ascent:
q
q
(300 m) +
e
e
(620 m) = 920 m
Cumulative Descent:
w
w
(320 m) +
r
r
(500 m) = 820 m
• Entering the Altimeter Mode starts a new altitude auto measurement session, but it does not reset the
current
ASC
and
DSC
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 cumulative ascent value of the current session (920 meters in the above example) is added
to the session’s starting
ASC
value. Also, the cumulative descent value of the current auto
measurement session (
–
820 meters in the above example) is added to the session’s starting
DSC
value.
• Note that any change in elevation when ascending that is less than 15 meters (49 feet) is not added to
the cumulative 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
cumulative descent value for the current Altimeter Mode auto measurement session.
Note
• The high altitude, low altitude, cumulative ascent, and cumulative descent values are retained in
memory when you exit the Altimeter Mode. To clear values, perform the procedure under “To delete a
single altitude record” (page E-74) or “To delete all altitude records” (page E-74).
E-66
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 defi ne relationships between altitude, air pressure, and
temperature.
0 m
500 m
1000 m
1500 m
2000 m
2500 m
3000 m
3500 m
4000 m
899 hPa
795 hPa
701 hPa
616 hPa
8.5°C
2°C
–4.5°C
–11°C
15°C1013 hPa
About 6.5°C
per 1000 m
About 8 hPa per 100 m
About 9 hPa per 100 m
About 10 hPa per 100 m
About 11 hPa per 100 m
About 12 hPa per 100 m
Altitude Air Pressure Temperature
0 ft.
2000 ft.
4000 ft.
6000 ft.
8000 ft.
10000 ft.
12000 ft.
14000 ft.
25.84 inHg
22.23 inHg
19.03 inHg
44.7°F
30.5°F
16.2°F
59.0°F29.92 inHg
About 3.6°F
per 1000 ft.
About 0.15 inHg per 200 ft.
About 0.17 inHg per 200 ft.
About 0.192 inHg per 200 ft.
About 0.21 inHg per 200 ft.
Source: International Civil Aviation Organization
E-67
• Note that the following conditions will prevent you from obtaining accurate readings:
When air pressure fl uctuates 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
(relative altitude)
Rooftop at an altitude of
230 m above sea level
(absolute altitude)
Sea Level
E-68
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 the fl ight crew.
E-69
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
TOKYO
(
TYO
) 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 each of the following
steps occurs.
• Hold SET appears on the digital display. ➝ HT fl a s h e s. ➝ Second
hand points to the current Home City code.
2. Use
D
to cycle through the settings on the digital display until the unit
setting screen is shown.
• See step 3 under “To change the current time and date settings
manually” (page E-31) for information about how to scroll through
setting screens.
E-70
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 the settings are the way you want, press
E
to exit the setting screen.
E-71
Precautions Concerning Simultaneous Measurement of Altitude and Temperature
Though you can perform altitude and temperature measurements at the same time, you should remember
that each of these measurements requires different conditions for best results. With temperature
measurement, it is best to remove the watch from your wrist in order to eliminate the effects of body heat.
In the case of altitude measurement, on the other hand, it is better to leave the watch on your wrist,
because doing so keeps the watch at a constant temperature, which contributes to more accurate altitude
measurements.
• To give altitude measurement priority, leave the watch on your wrist or in any other location where the
temperature of the watch is kept constant.
• To give temperature measurement priority, remove the watch from your wrist and allow it to hang freely
from your bag or in another location where it is not exposed to direct sunlight. Note that removing the
watch from your wrist can affect pressure sensor readings momentarily.