AAD Vigil Cuatro, User Manual

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3.4. Information regarding the Activation Altitude
Please be aware that the Vigil
®
Cuatro functions are based on measured air pressure. This parameter permits the
calculation of the exact altitude, in function of the registered air pressure, as well as the vertical speed related to a
pressure variation in a certain period of time.
For information : The Vigil
®
Cuatro is able to register pressure differences of 0,1 hPa which is equivalent
to an altitude difference of only ± 2,6 ft (or 0,8 meter)!
Important note: The registered pressure by the sensor will vary, according to the body position of the
skydiver (face to earth or back to earth) up to 10 hPa (=mbar) which is equivalent to +-260 ft (+- 79 m)!
Example: Let’s consider two skydivers in free fall, at exactly the same altitude but one is falling back to earth
and the second one is falling face to earth.
(I)
back to earth
Depression zone (burble)
No influence
Pressure sensor location
Pressure = X hPa
Vigil
®
Cuatro will register a pressure of X hPa
The stated or real altitude

y ft (or m)
( II ) Face to earth
AAD or pressure sensor
located in depression zone
(burble)
Pressure = X hPa – 10 hPa
Vigil
®
Cuatro in depression zone will register an up to 10 hPa
lower pressure, notwithstanding they are at the same level
The stated altitude

Y +( ± 260 ft) or +( ± 79 m)
Both at the same altitude Y
The influence of their falling position on their respective AAD reading is as follows:
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VIGIL Cuatro