Copter: mode_land sends dt to sqrt controller

ArduCopter/mode_land.cpp

@@ -184,7 +184,7 @@ void Copter::land_run_vertical_control(bool pause_descent)
         max_land_descent_velocity = MIN(max_land_descent_velocity, -abs(g.land_speed));
 
         // Compute a vertical velocity demand such that the vehicle approaches LAND_START_ALT. Without the below constraint, this would cause the vehicle to hover at LAND_START_ALT.
-        cmb_rate = AC_AttitudeControl::sqrt_controller(LAND_START_ALT-alt_above_ground, g.p_alt_hold.kP(), pos_control->get_accel_z());
+        cmb_rate = AC_AttitudeControl::sqrt_controller(LAND_START_ALT-alt_above_ground, g.p_alt_hold.kP(), pos_control->get_accel_z(), G_Dt);
 
         // Constrain the demanded vertical velocity so that it is between the configured maximum descent speed and the configured minimum descent speed.
         cmb_rate = constrain_float(cmb_rate, max_land_descent_velocity, -abs(g.land_speed));