diff --git a/conf/messages.xml b/conf/messages.xml
index bfc9a6ec82..00af2a2946 100644
--- a/conf/messages.xml
+++ b/conf/messages.xml
@@ -367,9 +367,9 @@
 
   <message name="INFRARED" id="18">
     <field name="ac_id" type="string"/>
-    <field name="gps_hybrid_mode" type="uint8" values="OFF|ON"/>
+    <field name="gps_hybrid_mode" type="string" values="OFF|ON"/>
     <field name="gps_hybrid_factor" type="float"/>
-    <field name="contrast_status" type="string" values="DEFAULT|WAITING|SET"/>
+    <field name="contrast_status" type="string" values="DEFAULT|WAITING|SET|SKIPPED"/>
     <field name="contrast_value" type="int16"/>
   </message>
 
diff --git a/sw/airborne/autopilot/main.c b/sw/airborne/autopilot/main.c
index 7d4da6ce88..d1a2cc918b 100644
--- a/sw/airborne/autopilot/main.c
+++ b/sw/airborne/autopilot/main.c
@@ -475,10 +475,13 @@ inline void periodic_task( void ) {
       DOWNLINK_SEND_CIRCLE(&circle_x, &circle_y, &circle_radius); }
     if (in_segment) {
       DOWNLINK_SEND_SEGMENT(&segment_x_1, &segment_y_1, &segment_x_2, &segment_y_2); }
-		if (calib_status == WAITING_CALIB_CONTRAST) {
-			DOWNLINK_SEND_CALIB_START(); }
-		if (calib_status == CALIB_DONE && !estimator_flight_time) {
-			DOWNLINK_SEND_CALIB_CONTRAST(&ir_contrast); }
+    if (!estimator_flight_time) {
+      if (calib_status == WAITING_CALIB_CONTRAST) {
+	DOWNLINK_SEND_CALIB_START();
+      } else if (calib_status == CALIB_DONE) {
+	DOWNLINK_SEND_CALIB_CONTRAST(&ir_contrast);
+      }
+    }
   }
   switch(_4Hz) {
   case 0:
diff --git a/sw/ground_segment/tmtc/receive.ml b/sw/ground_segment/tmtc/receive.ml
index f6b24cd2c4..01c4535a3f 100644
--- a/sw/ground_segment/tmtc/receive.ml
+++ b/sw/ground_segment/tmtc/receive.ml
@@ -54,6 +54,7 @@ let ap_modes = [|"MANUAL";"AUTO1";"AUTO2";"HOME"|]
 let gaz_modes = [|"MANUAL";"GAZ";"CLIMB";"ALT"|]
 let lat_modes = [|"MANUAL";"ROLL_RATE";"ROLL";"COURSE"|]
 let gps_modes = [|"NOFIX";"DRO";"2D";"3D";"GPSDRO"|]
+let gps_hybrid_modes = [|"OFF";"ON"|]
 let if_modes = [|"OFF";"DOWN";"UP"|]
 let horiz_modes = [|"WAYPOINT";"ROUTE";"CIRCLE"|]
 
@@ -263,7 +264,9 @@ let log_and_parse = fun log ac_name a msg values ->
 	a.rpm <- a.throttle *. 100.;
 	a.bat <- fvalue "voltage" /. 10.;
 	a.stage_time <- ivalue "stage_time";
-	a.block_time <- ivalue "block_time"
+	a.block_time <- ivalue "block_time";
+	if a.flight_time > 0 && a.infrared.contrast_status = "WAITING" then
+	  a.infrared.contrast_status <- "SKIPPED"
     | "PPRZ_MODE" ->
 	a.ap_mode <- check_index (ivalue "ap_mode") ap_modes "AP_MODE";
 	a.gaz_mode <- check_index (ivalue "ap_gaz") gaz_modes "AP_GAZ";
@@ -284,7 +287,7 @@ let log_and_parse = fun log ac_name a msg values ->
 	  else if mcu1_status land 0b100 > 0
 	  then "AUTO"
 	  else "MANUAL";
-	a.infrared.gps_hybrid_mode <- ivalue "lls_calib"
+	a.infrared.gps_hybrid_mode <- check_index (ivalue "lls_calib") gps_hybrid_modes "HYBRID MODE"
     | "CAM" ->
 	a.cam.phi <- (Deg>>Rad) (fvalue  "phi");
 	a.cam.theta <- (Deg>>Rad) (fvalue  "theta");
@@ -356,8 +359,9 @@ let send_fbw = fun a ->
   Ground_Pprz.message_send my_id "FLY_BY_WIRE"  values
 
 let send_infrared = fun a ->
+  let gps_hybrid_mode = get_indexed_value gps_hybrid_modes a.infrared.gps_hybrid_mode in
   let values = [ "ac_id", Pprz.String a.id;
-		 "gps_hybrid_mode", Pprz.Int a.infrared.gps_hybrid_mode;
+		 "gps_hybrid_mode", Pprz.String gps_hybrid_mode;
 		 "gps_hybrid_factor", Pprz.Float a.infrared.gps_hybrid_factor;
 		 "contrast_status", Pprz.String a.infrared.contrast_status;
 		 "contrast_value", Pprz.Int a.infrared.contrast_value
diff --git a/sw/lib/ocaml/pprz.ml b/sw/lib/ocaml/pprz.ml
index 5644aadaaa..801b4f7d18 100644
--- a/sw/lib/ocaml/pprz.ml
+++ b/sw/lib/ocaml/pprz.ml
@@ -120,17 +120,24 @@ let field_of_xml = fun xml ->
   let f = try Xml.attrib xml "format" with _ -> default_format t in
   (ExtXml.attrib xml "name", { _type = t; fformat = f })
 
+let string_of_values = fun vs ->
+  String.concat " " (List.map (fun (a,v) -> sprintf "%s=%s" a (string_of_value v)) vs)
+
+let assoc = fun a vs -> 
+  try List.assoc a vs with Not_found -> 
+    failwith (sprintf "Attribute '%s' not found in '%s'" a (string_of_values vs))
+
 let float_assoc = fun (a:string) vs -> 
-  match List.assoc a vs with
+  match assoc a vs with
     Float x -> x
   | _ -> invalid_arg "Pprz.float_assoc"
 
 let int_assoc = fun (a:string) vs -> 
-  match List.assoc a vs with
+  match assoc a vs with
     Int x -> x
   | _ -> invalid_arg "Pprz.int_assoc"
 
-let string_assoc = fun (a:string) (vs:values) -> string_of_value (List.assoc a vs)
+let string_assoc = fun (a:string) (vs:values) -> string_of_value (assoc a vs)
 
 
 
diff --git a/sw/simulator/sim.ml b/sw/simulator/sim.ml
index 82cfc29001..f3ef0a2e82 100644
--- a/sw/simulator/sim.ml
+++ b/sw/simulator/sim.ml
@@ -123,7 +123,7 @@ module Make(AircraftItl : AIRCRAFT_ITL) = struct
       gps_availability := Pprz.int_assoc "gps_availability" vs;
       wind_x := Pprz.float_assoc "wind_east" vs;      
       wind_y := Pprz.float_assoc "wind_north" vs;      
-      infrared_contrast := Pprz.float_assoc "ir_contrast" vs; (** FIXME *)
+      infrared_contrast := Pprz.float_assoc "ir_contrast" vs;
       time_scale#set_value (Pprz.float_assoc "time_scale" vs)
     in
 
diff --git a/sw/simulator/sim_ap.c b/sw/simulator/sim_ap.c
index 2a42254d18..b2b5fdab31 100644
--- a/sw/simulator/sim_ap.c
+++ b/sw/simulator/sim_ap.c
@@ -1,5 +1,5 @@
 /* Definitions and declarations required to compile autopilot code on a
-   i386 architecture. Binding for OCaml. */
+   i386 architecture. Bindings for OCaml. */
 
 #include <stdio.h>
 #include <sys/time.h>
diff --git a/sw/simulator/sim_ir.c b/sw/simulator/sim_ir.c
index 4c97e74251..eae0a6b04a 100644
--- a/sw/simulator/sim_ir.c
+++ b/sw/simulator/sim_ir.c
@@ -1,4 +1,9 @@
-/* Infrared soft simulation. OCaml binding. */
+/** \file sim_ir.c
+ *  \brief Regroup functions to simulate autopilot/infrared.c
+ *
+ * Infrared soft simulation. OCaml binding.
+ */
+
 
 #include <inttypes.h>
 #include "airframe.h"