Flytec 4010 * - Manual (Page 8)

Operating Instructions FLYTEC 4010 7
When switched on, the instrument settings correspond to those valid when the instrument was
last switched off.
When first switched on, the instrument displays the approximate charging status of the batte-
ries in the vario bar display. If the display shows approximately 50% of the maximum display
in the green sector, the batteries are still half full. If the display is in the red sector, the batte-
ries must be changed. If the batteries are low on charge during a flight, PO will light up briefly
in the digital vario display and, at the same time, the charging status of the batteries is shown
in the bar display.
The battery life of the instrument using alkaline batteries is 160 hours. Rechargeable batteries
can also be used. However, operating time is substantially shorter with these (total operating
time is approximately 40 - 50 hours).
Alkaline batteries can also be recharged several times using the appropriate charging unit (no
fast chargers!).
The altimeter
General remarks
How does an altimeter work?
An altimeter is really a barometer because it does not measure altitude directly but pressure.
The altitude is then calculated from the pressure. For the purpose of calculating absolute alti-
tude (according to the international formula for altitude), the pressure at sea-level is assumed
as being zero-point pressure.
Why does pressure change with altitude? The air pressure at a point on Earth is produced by
the weight of the atmospheric air above it. This is why air pressure decreases with altitude -
there is less air above your head! At 500 meters above sea-level, a pressure change of 1 mbar
corresponds to a difference in altitude of about 8 meters.
In practice, however, it is not quite that simple as other factors also have an influence on air
pressure. Pressure also depends on temperature and, of course, weather. On a stable day,
there can be air pressure fluctuations of 1 mbar caused by temperatures and this corresponds
to a difference in altitude of ± 10 meters. Depending on the weather, air pressure at sea-level
(QNH) can be between 950 mbar and 1050 mbar. In order to eliminate this weather effect, an
altimeter needs continual recalibration. This means that the altimeter must be set at a known
altitude to display that same altitude.