diff --git a/ArduCopter/mode.cpp b/ArduCopter/mode.cpp
index b0dc674e426..7fda97e79cf 100644
--- a/ArduCopter/mode.cpp
+++ b/ArduCopter/mode.cpp
@@ -989,12 +989,12 @@ float Mode::get_pilot_desired_yaw_rate_rads() const
 // pass-through functions to reduce code churn on conversion;
 // these are candidates for moving into the Mode base
 // class.
-float Mode::get_pilot_desired_climb_rate_cms()
+float Mode::get_pilot_desired_climb_rate_cms() const
 {
     return copter.get_pilot_desired_climb_rate_cms();
 }
 
-float Mode::get_non_takeoff_throttle()
+float Mode::get_non_takeoff_throttle() const
 {
     return copter.get_non_takeoff_throttle();
 }
@@ -1013,22 +1013,22 @@ void Mode::set_land_complete(bool b)
     return copter.set_land_complete(b);
 }
 
-GCS_Copter &Mode::gcs()
+GCS_Copter &Mode::gcs() const
 {
     return copter.gcs();
 }
 
-float Mode::get_pilot_speed_up_ms()
+float Mode::get_pilot_speed_up_ms() const
 {
     return g.pilot_speed_up * 0.01;
 }
 
-float Mode::get_pilot_speed_dn_ms()
+float Mode::get_pilot_speed_dn_ms() const
 {
     return copter.get_pilot_speed_dn() * 0.01;
 }
 
-float Mode::get_pilot_accel_mss()
+float Mode::get_pilot_accel_U_mss() const
 {
     return g.pilot_accel_z * 0.01;
 }
diff --git a/ArduCopter/mode.h b/ArduCopter/mode.h
index 94b6c3a5049..b4b613ef289 100644
--- a/ArduCopter/mode.h
+++ b/ArduCopter/mode.h
@@ -393,15 +393,15 @@ public:
     // pass-through functions to reduce code churn on conversion;
     // these are candidates for moving into the Mode base
     // class.
-    float get_pilot_desired_climb_rate_cms();
-    float get_non_takeoff_throttle(void);
-    void update_simple_mode(void);
+    float get_pilot_desired_climb_rate_cms() const;
+    float get_non_takeoff_throttle() const;
+    void update_simple_mode();
     bool set_mode(Mode::Number mode, ModeReason reason);
     void set_land_complete(bool b);
-    GCS_Copter &gcs();
-    float get_pilot_speed_up_ms(void);
-    float get_pilot_speed_dn_ms(void);
-    float get_pilot_accel_mss(void);
+    GCS_Copter &gcs() const;
+    float get_pilot_speed_up_ms() const;
+    float get_pilot_speed_dn_ms() const;
+    float get_pilot_accel_U_mss() const;
     // end pass-through functions
 };
 
diff --git a/ArduCopter/mode_althold.cpp b/ArduCopter/mode_althold.cpp
index 567b14556ab..81fcc43d684 100644
--- a/ArduCopter/mode_althold.cpp
+++ b/ArduCopter/mode_althold.cpp
@@ -15,8 +15,8 @@ bool ModeAltHold::init(bool ignore_checks)
     }
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     return true;
 }
@@ -26,7 +26,7 @@ bool ModeAltHold::init(bool ignore_checks)
 void ModeAltHold::run()
 {
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // apply SIMPLE mode transform to pilot inputs
     update_simple_mode();
diff --git a/ArduCopter/mode_autotune.cpp b/ArduCopter/mode_autotune.cpp
index c25f48f1a60..c9e0a0d4b9d 100644
--- a/ArduCopter/mode_autotune.cpp
+++ b/ArduCopter/mode_autotune.cpp
@@ -82,8 +82,8 @@ void AutoTune::get_pilot_desired_rp_yrate_rad(float &des_roll_rad, float &des_pi
 void AutoTune::init_z_limits()
 {
     // set vertical speed and acceleration limits
-    copter.pos_control->set_max_speed_accel_U_m(-copter.flightmode->get_pilot_speed_dn_ms(), copter.flightmode->get_pilot_speed_up_ms(), copter.flightmode->get_pilot_accel_mss());
-    copter.pos_control->set_correction_speed_accel_U_m(-copter.flightmode->get_pilot_speed_dn_ms(), copter.flightmode->get_pilot_speed_up_ms(), copter.flightmode->get_pilot_accel_mss());
+    copter.pos_control->set_max_speed_accel_U_m(-copter.flightmode->get_pilot_speed_dn_ms(), copter.flightmode->get_pilot_speed_up_ms(), copter.flightmode->get_pilot_accel_U_mss());
+    copter.pos_control->set_correction_speed_accel_U_m(-copter.flightmode->get_pilot_speed_dn_ms(), copter.flightmode->get_pilot_speed_up_ms(), copter.flightmode->get_pilot_accel_U_mss());
 }
 
 #if HAL_LOGGING_ENABLED
diff --git a/ArduCopter/mode_circle.cpp b/ArduCopter/mode_circle.cpp
index d3e5d055b67..3ad6dd2990c 100644
--- a/ArduCopter/mode_circle.cpp
+++ b/ArduCopter/mode_circle.cpp
@@ -15,8 +15,8 @@ bool ModeCircle::init(bool ignore_checks)
     // set speed and acceleration limits
     pos_control->set_max_speed_accel_NE_m(wp_nav->get_default_speed_NE_ms(), wp_nav->get_wp_acceleration_mss());
     pos_control->set_correction_speed_accel_NE_m(wp_nav->get_default_speed_NE_ms(), wp_nav->get_wp_acceleration_mss());
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // initialise circle controller including setting the circle center based on vehicle speed
     copter.circle_nav->init();
@@ -48,7 +48,7 @@ void ModeCircle::run()
 {
     // set speed and acceleration limits
     pos_control->set_max_speed_accel_NE_m(wp_nav->get_default_speed_NE_ms(), wp_nav->get_wp_acceleration_mss());
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // Check for any change in params and update in real time
     copter.circle_nav->check_param_change();
diff --git a/ArduCopter/mode_flowhold.cpp b/ArduCopter/mode_flowhold.cpp
index c33c9682cb9..66da2687439 100644
--- a/ArduCopter/mode_flowhold.cpp
+++ b/ArduCopter/mode_flowhold.cpp
@@ -89,8 +89,8 @@ bool ModeFlowHold::init(bool ignore_checks)
     }
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // initialise the vertical position controller
     if (!copter.pos_control->is_active_U()) {
@@ -233,7 +233,7 @@ void ModeFlowHold::run()
     update_height_estimate();
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // apply SIMPLE mode transform to pilot inputs
     update_simple_mode();
diff --git a/ArduCopter/mode_loiter.cpp b/ArduCopter/mode_loiter.cpp
index 4df2dbd37b7..d50c20d52d2 100644
--- a/ArduCopter/mode_loiter.cpp
+++ b/ArduCopter/mode_loiter.cpp
@@ -27,8 +27,8 @@ bool ModeLoiter::init(bool ignore_checks)
     }
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
 #if AC_PRECLAND_ENABLED
     _precision_loiter_active = false;
@@ -84,7 +84,7 @@ void ModeLoiter::run()
     float target_climb_rate_cms = 0.0f;
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // apply SIMPLE mode transform to pilot inputs
     update_simple_mode();
diff --git a/ArduCopter/mode_poshold.cpp b/ArduCopter/mode_poshold.cpp
index 4dadff8064e..07a2df0fa0f 100644
--- a/ArduCopter/mode_poshold.cpp
+++ b/ArduCopter/mode_poshold.cpp
@@ -25,8 +25,8 @@
 bool ModePosHold::init(bool ignore_checks)
 {
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // initialise the vertical position controller
     if (!pos_control->is_active_U()) {
@@ -75,7 +75,7 @@ void ModePosHold::run()
     }
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
     loiter_nav->clear_pilot_desired_acceleration();
 
     // apply SIMPLE mode transform to pilot inputs
diff --git a/ArduCopter/mode_sport.cpp b/ArduCopter/mode_sport.cpp
index 50e900de4f3..8f79bedc91b 100644
--- a/ArduCopter/mode_sport.cpp
+++ b/ArduCopter/mode_sport.cpp
@@ -10,8 +10,8 @@
 bool ModeSport::init(bool ignore_checks)
 {
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // initialise the vertical position controller
     if (!pos_control->is_active_U()) {
@@ -26,7 +26,7 @@ bool ModeSport::init(bool ignore_checks)
 void ModeSport::run()
 {
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // apply SIMPLE mode transform
     update_simple_mode();
diff --git a/ArduCopter/mode_zigzag.cpp b/ArduCopter/mode_zigzag.cpp
index 4a19b7148ad..7233c574cc6 100644
--- a/ArduCopter/mode_zigzag.cpp
+++ b/ArduCopter/mode_zigzag.cpp
@@ -80,8 +80,8 @@ bool ModeZigZag::init(bool ignore_checks)
     loiter_nav->init_target();
 
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
-    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
+    pos_control->set_correction_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // initialise the vertical position controller
     if (!pos_control->is_active_U()) {
@@ -111,7 +111,7 @@ void ModeZigZag::exit()
 void ModeZigZag::run()
 {
     // set vertical speed and acceleration limits
-    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_mss());
+    pos_control->set_max_speed_accel_U_m(-get_pilot_speed_dn_ms(), get_pilot_speed_up_ms(), get_pilot_accel_U_mss());
 
     // set the direction and the total number of lines
     zigzag_direction = (Direction)constrain_int16(_direction, 0, 3);