The LX7000 in NETTO-mode is trying to compute what the air around you is doing.

Since your ship's (Computerized)polar tells the LX that it it should be sinking at 1.8 kt and the Vario information tells the computer that is is at zero sink, it tells you that the "airmass" around the ship is moving up at 1.8k.

Note that once you have some airspeed (above the point where the polar-curve makes sense), the LX will take the sink at that speed from the polar and compare that sink to the Vario-indicated sink to compute air vertical motion.


Heinz