+ &FGInterface::get_V_down, &FGInterface::set_V_down, false);
+
+ fgTie("/velocities/north-relground-fps", this,
+ &FGInterface::get_V_north_rel_ground);
+ fgTie("/velocities/east-relground-fps", this,
+ &FGInterface::get_V_east_rel_ground);
+ fgTie("/velocities/down-relground-fps", this,
+ &FGInterface::get_V_down_rel_ground);
+