diff --git a/sw/airborne/firmwares/fixedwing/ap_downlink.h b/sw/airborne/firmwares/fixedwing/ap_downlink.h
index d1b25251ed..30dee8aec7 100644
--- a/sw/airborne/firmwares/fixedwing/ap_downlink.h
+++ b/sw/airborne/firmwares/fixedwing/ap_downlink.h
@@ -96,7 +96,7 @@ extern uint8_t telemetry_mode_Ap_DefaultChannel;
       DOWNLINK_SEND_ATTITUDE(_trans, _dev, &estimator_phi, &estimator_psi, &estimator_theta); \
 })
 
-#define PERIODIC_SEND_PPRZ_MODE(_trans, _dev) DOWNLINK_SEND_PPRZ_MODE(_trans, _dev, &pprz_mode, &v_ctl_mode, &lateral_mode, &horizontal_mode, &rc_settings_mode, &mcu1_status);
+
 #define PERIODIC_SEND_DESIRED(_trans, _dev) DOWNLINK_SEND_DESIRED(_trans, _dev, &h_ctl_roll_setpoint, &h_ctl_pitch_loop_setpoint, &h_ctl_course_setpoint, &desired_x, &desired_y, &v_ctl_altitude_setpoint, &v_ctl_climb_setpoint);
 
 #if USE_INFRARED
@@ -123,9 +123,15 @@ extern uint8_t telemetry_mode_Ap_DefaultChannel;
   DownlinkSendWp(_trans, _dev, i);	    \
 }
 
-#ifdef RADIO_CONTROL_SETTINGS
+#if defined RADIO_CALIB && defined RADIO_CONTROL_SETTINGS
+#include "rc_settings.h"
+#define PERIODIC_SEND_PPRZ_MODE(_trans, _dev) DOWNLINK_SEND_PPRZ_MODE(_trans, _dev, &pprz_mode, &v_ctl_mode, &lateral_mode, &horizontal_mode, &rc_settings_mode, &mcu1_status);
 #define PERIODIC_SEND_SETTINGS(_trans, _dev) if (!RcSettingsOff()) DOWNLINK_SEND_SETTINGS(_trans, _dev, &slider_1_val, &slider_2_val);
 #else
+#define PERIODIC_SEND_PPRZ_MODE(_trans, _dev) {                         \
+    uint8_t rc_settings_mode_none = 0;                                  \
+    DOWNLINK_SEND_PPRZ_MODE(_trans, _dev, &pprz_mode, &v_ctl_mode, &lateral_mode, &horizontal_mode, &rc_settings_mode_none, &mcu1_status); \
+  }
 #define PERIODIC_SEND_SETTINGS(_trans, _dev) {}
 #endif
 
diff --git a/sw/airborne/firmwares/fixedwing/autopilot.h b/sw/airborne/firmwares/fixedwing/autopilot.h
index d1d55a814a..1f122a3690 100644
--- a/sw/airborne/firmwares/fixedwing/autopilot.h
+++ b/sw/airborne/firmwares/fixedwing/autopilot.h
@@ -67,16 +67,12 @@ extern bool_t kill_throttle;
 
 #define FLOAT_OF_PPRZ(pprz, center, travel) ((float)pprz / (float)MAX_PPRZ * travel + center)
 
-extern uint8_t fatal_error_nb;
-
 #define THROTTLE_THRESHOLD_TAKEOFF (pprz_t)(MAX_PPRZ * 0.9)
 
 extern uint8_t lateral_mode;
 extern uint8_t vsupply;
 extern float energy;
 
-extern float slider_1_val, slider_2_val;
-
 extern bool_t launch;
 
 extern uint8_t light_mode;
@@ -91,8 +87,6 @@ extern bool_t sum_err_reset;
   (_mode != new_mode ? _mode = new_mode, TRUE : FALSE); \
 })
 
-void periodic_task( void );
-//void telecommand_task(void);
 
 #ifdef RADIO_CONTROL
 #include "subsystems/radio_control.h"
@@ -117,10 +111,4 @@ extern bool_t power_switch;
 }
 
 
-/* For backward compatibility with old airframe files */
-#include "generated/airframe.h"
-#ifndef CONTROL_RATE
-#define CONTROL_RATE 20
-#endif
-
 #endif /* AUTOPILOT_H */
diff --git a/sw/airborne/firmwares/fixedwing/main_ap.c b/sw/airborne/firmwares/fixedwing/main_ap.c
index c59dece80d..dfdf0f0a8a 100644
--- a/sw/airborne/firmwares/fixedwing/main_ap.c
+++ b/sw/airborne/firmwares/fixedwing/main_ap.c
@@ -98,17 +98,9 @@ static inline void on_gps_solution( void );
 #endif
 
 
-#define LOW_BATTERY_DECIVOLT (CATASTROPHIC_BAT_LEVEL*10)
-
-
-/** FIXME: should be in rc_settings but required by telemetry (ap_downlink.h)*/
-uint8_t rc_settings_mode = 0;
-
-/** Define minimal speed for takeoff in m/s */
-#define MIN_SPEED_FOR_TAKEOFF 5.
-
 bool_t power_switch;
-uint8_t fatal_error_nb = 0;
+
+// what version is this ????
 static const uint16_t version = 1;
 
 uint8_t pprz_mode = PPRZ_MODE_AUTO2;
@@ -122,14 +114,23 @@ static uint8_t  mcu1_ppm_cpt;
 
 bool_t kill_throttle = FALSE;
 
-float slider_1_val, slider_2_val;
-
 bool_t launch = FALSE;
 
-uint8_t vsupply;	// deciVolt
+
+/** Supply voltage in deciVolt.
+ * This the ap copy of the measurement from fbw
+ */
+uint8_t vsupply;
+
+/** Supply current in milliAmpere.
+ * This the ap copy of the measurement from fbw
+ */
 static int32_t current;	// milliAmpere
 
-float energy;       // Fuel consumption (mAh)
+/** Fuel consumption (mAh)
+ * TODO: move to electrical subsystem
+ */
+float energy;
 
 bool_t gps_lost = FALSE;
 
@@ -381,11 +382,6 @@ static inline void telecommand_task( void ) {
 
 /**************************** Periodic tasks ***********************************/
 
-/** Define number of message at initialisation */
-#define INIT_MSG_NB 2
-
-uint8_t ac_ident = AC_ID;
-
 /**
  * Send a series of initialisation messages followed by a stream of periodic ones.
  * Called at 60Hz.
@@ -535,6 +531,9 @@ void sensors_task( void ) {
 #endif // USE_IMU
 }
 
+
+
+
 /** Maximum time allowed for low battery level before going into kill mode */
 #define LOW_BATTERY_DELAY 5
 
@@ -543,6 +542,9 @@ void sensors_task( void ) {
 #define KILL_MODE_DISTANCE (1.5*MAX_DIST_FROM_HOME)
 #endif
 
+/** Define minimal speed for takeoff in m/s */
+#define MIN_SPEED_FOR_TAKEOFF 5.
+
 /** monitor stuff run at 1Hz */
 void monitor_task( void ) {
   if (estimator_flight_time)
@@ -552,7 +554,7 @@ void monitor_task( void ) {
 #endif
 
   static uint8_t t = 0;
-  if (vsupply < LOW_BATTERY_DECIVOLT)
+  if (vsupply < CATASTROPHIC_BAT_LEVEL*10)
     t++;
   else
     t = 0;
diff --git a/sw/airborne/rc_settings.c b/sw/airborne/rc_settings.c
index d64857a4b4..15573d398a 100644
--- a/sw/airborne/rc_settings.c
+++ b/sw/airborne/rc_settings.c
@@ -34,6 +34,8 @@
 #include "inter_mcu.h"
 #include "firmwares/fixedwing/stabilization/stabilization_attitude.h"
 
+uint8_t rc_settings_mode = 0;
+float slider_1_val, slider_2_val;
 
 #define ParamValInt16(param_init_val, param_travel, cur_pulse, init_pulse) \
 (param_init_val + (int16_t)(((float)(cur_pulse - init_pulse)) * param_travel / (float)MAX_PPRZ))
diff --git a/sw/airborne/rc_settings.h b/sw/airborne/rc_settings.h
index 2fd8677e25..796a881e15 100644
--- a/sw/airborne/rc_settings.h
+++ b/sw/airborne/rc_settings.h
@@ -23,8 +23,9 @@
  */
 
 
-/** \file rc_settings.h
- *  \brief Variable setting though the radio control
+/**
+ * @file rc_settings.h
+ * Variable setting though the radio control
  *
  * The 'rc_control' section of a XML flight plan allows the user to change the
  * value of an autopilot internal variable through the rc transmitter.
@@ -33,6 +34,7 @@
  */
 
 #ifndef RC_SETTINGS_H
+#define RC_SETTINGS_H
 
 #if defined RADIO_CALIB && defined RADIO_CONTROL_SETTINGS
 
@@ -43,8 +45,16 @@
 #define RC_SETTINGS_MODE_DOWN      1
 #define RC_SETTINGS_MODE_UP        2
 
+/** rc settings mode
+ *  can be either
+ *  - #RC_SETTINGS_MODE_NONE
+ *  - #RC_SETTINGS_MODE_DOWN
+ *  - #RC_SETTINGS_MODE_UP
+ */
 extern uint8_t rc_settings_mode;
 
+extern float slider_1_val, slider_2_val;
+
 void rc_settings(bool_t mode_changed);
 
 #define RcSettingsOff() (rc_settings_mode==RC_SETTINGS_MODE_NONE)