During rapid altitude changes, the chosen “SEA” setting is not stable but shifts away and gives quite impossible values. Why does the sea pressure setting shift?
When the sea level pressure or the reference altitude is set, it is correct within a range which may include rounded values. The strange sea level pressure values measured with your Suunto wristop computer result from the following calculation principles. When vertical changes are included, the pressure change can be handled in two ways: In some models, the sea level pressure value is not fixed and it starts changing according to the absolute pressure change. So, when you’re moving in a vertical direction, both the altitude reading and the sea level pressure reading are changing equally to correspond to the change in absolute pressure. In other models, the sea level value is kept fixed as it was when the reference altitude was given and it is updated only when a new reference altitude or new sea level pressure is set. Both principles have their advantages and disadvantages: The fixed sea level value can never be unrealistic, but it will also be fixed when you stay at a constant altitud
