Operation Manual

LX90xx system Version 4.0 February 2014
Page 33 of 151
6.1.1.2 Safety Altitude
This setting is the altitude reserve or safety altitude and is the height that the instrument
adds to the final glide altitude required so that the glider arrives over the final glide
destination at the selected safety altitude. Once the safety altitude has been specified, the
pilot has to keep the final glide indicator on 0 to arrive at the safety altitude.
6.1.1.3 Altitude source
The system has two pressure altitude sensors. One is built into the main display unit and is
used for the IGC recorder and the second one is built into the vario unit and is connected to
the glider pitot-static system. Changing the altitude source defines which sensor is used for
pressure altitude used in program.
6.1.1.4 Magnetic Variation
The main display unit has a built-in Earth magnetic field model. If Auto variation is checked
the magnetic variation is derived from this model, otherwise the user can enter a custom
value.
6.1.1.5 ETA/ETE Calculation
In changing this value you may choose from four different methods to calculate the
estimated time of arrival to the navigational point. Calculation is always divided into straight
flight and climb time calculations.
 MacCready uses the Polar data and MacCready setting to calculate speed to fly and
climb rate.
 Vario uses the last four thermals average to compute climb rate and uses this value to
calculate speed to fly.
 Avg.Speed & Vario uses the average ground speed over the last 5 minutes for
distance and Vario statistics for climb rate.
 Avg.Speed & MC uses the average ground speed over the last 5 minutes for distance
and MacCready.
All four methods of calculating ETA and ETE (Estimate Time of Arrival & Estimate Time
Elapsed) take into account glider altitude, wind and safety (arrival) altitude thus ensuring
that the calculation made is the best possible.
Suggested methods for competition pilots are Avg.Speed & Vario or
Avg.Speed & Mc.
6.1.1.6 Soaring Start*
Soaring start is the time when the glider starts soaring (released from tow, engine switched
off). A soaring start time is needed to start the flight optimization.