User manual

XCSoar User Manual
Above Below
The final glide bar has been modified to show the effect of Mac-
Cready setting on the altitude difference to complete the task. The
display shows in an arrow outline the altitude difference calculated
at zero MacCready, as well as the usual filled arrow that displays
the altitude difference calculated at the current MacCready setting.
The number shown in the box next to the final glide bar still shows
the altitude difference at the current MacCready setting.
Examples of the appearance in various configurations is shown
below:
Above final glide at Mc= M and Mc= 0 : Here the display shows that at the current Mac-
Cready setting, the aircraft is above final glide (filled arrow).
The hollow arrow shows the additional excess height.
Below final glide at Mc= M, and above at Mc= 0 : Here the display shows that at the current
MacCready setting, the aircraft is below final glide (filled
red arrow). The hollow green arrow shows that at Mc= 0,
the aircraft is above final glide.
In this situation, if the glider is climbing, the pilot can as-
sess whether to leave the thermal early and commence a final
glide descent at a reduced MacCready setting; or continue to
climb. It is useful to switch on the auto MacCready setting
as this will automatically adjust the MacCready value to the
optimal value — and then it is simple for the pilot to com-
pare the achieved lift rate with the MacCready value. When
the achieved lift rate drops below the MacCready value, the
thermal should be left.
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