diff --git a/central-manager/lib/header.h b/central-manager/lib/header.h
index f3ec03c..55c16cb 100644
--- a/central-manager/lib/header.h
+++ b/central-manager/lib/header.h
@@ -56,8 +56,10 @@
 
 
         struct context_unit{
-            int          socket; // socket associée à un avion
-            struct plane data;   // données d'un avion
+            int             socket; // socket associée à un avion
+            struct plane    data;   // données d'un avion
+            pthread_mutex_t mutex;  // socket mutual exclusion
+            char            token;  // if want to have mutex
         };
 
         struct context{
diff --git a/central-manager/lib/local/handler.c b/central-manager/lib/local/handler.c
index ae96e0b..fea6c7e 100644
--- a/central-manager/lib/local/handler.c
+++ b/central-manager/lib/local/handler.c
@@ -65,30 +65,17 @@ void* managePlane(void* THREADABLE_ARGS){
 
 	while( 1 ){
 
+
+
 		/* (2) Récupération de la requête
 		---------------------------------------------------------*/
-		/* (1) Premier byte pour savoir si la réponse est pour nous
-		---------------------------------------------------------*/
+
 		/* 1. On lit sur la socket */
-		read = recv(SOCKET, buffer, 1, 0);
-
-		/* 2. Si erreur reception (-1:erreur, 0:fermeture client propre) */
-		if( read <= 0 ){
-			if( DEBUGMOD&BUF ) printf("{tcp_com}(%d)             read: %d -> must exit thread\n", index, read);
-			break;
-		}
-
-		/* 3. Si pas pour nous -> on attends puis on reboucle */
-		if( buffer[0] == 0x55 ){ // '01010101'(2) '55'(16)
-			if( DEBUGMOD&BUF ) printf("{tcp_com}(%d)             Let request to update routine\n", index);
-			sleep(0.5);
-			continue;
-		}
-
-		/* (2) Données
-		---------------------------------------------------------*/
-		/* 1. On lit sur la socket */
-		read = recv(SOCKET, buffer+1, MAX_BUF_LEN-1, 0);
+		if( pindex > -1 && arg->sgca->unit[pindex].token != 0 )
+			sleep(1);
+		if( pindex > -1 ) pthread_mutex_lock(&arg->sgca->unit[pindex].mutex);
+		read = recv(SOCKET, buffer, MAX_BUF_LEN, 0);
+		if( pindex > -1 ) pthread_mutex_unlock(&arg->sgca->unit[pindex].mutex);
 
 		/* 2.1. Si erreur reception (-1:erreur, 0:fermeture client propre) */
 		if( read <= 0 ){
@@ -97,8 +84,8 @@ void* managePlane(void* THREADABLE_ARGS){
 		}
 
 		/* 2.2. Si message trop court */
-		if( read != PLANE_LEN-1 ){
-			if( DEBUGMOD&BUF ) printf("{tcp_com}(%d)             read: %d (expected: %d)\n", index, read+1, (int) PLANE_LEN);
+		if( read != PLANE_LEN ){
+			if( DEBUGMOD&BUF ) printf("{tcp_com}(%d)             read: %d (expected: %d)\n", index, read, (int) PLANE_LEN);
 			continue;
 		}
 
@@ -147,6 +134,8 @@ void* managePlane(void* THREADABLE_ARGS){
 			arg->sgca->n++;
 			arg->sgca->unit                = (struct context_unit*) realloc(arg->sgca->unit,   sizeof(struct context_unit)*arg->sgca->n + 1);
 			arg->sgca->unit[pindex].socket = SOCKET;
+			arg->sgca->unit[pindex].token  = 0;
+			pthread_mutex_init(&arg->sgca->unit[pindex].mutex, NULL);
 			printf("{tcp_com}(%d)             plane '%s' (#%d) created\n", index, data.code, pindex);
 
 		}
@@ -433,6 +422,10 @@ void* manageCtrlTerm(void* THREADABLE_ARGS){
 			count += last; last = sizeof(int);  memcpy(buffer+count, &request.update.spd, last );
 			count += last;
 
+			// utilisation socket
+			arg->sgca->unit[pindex].token = 1;
+			pthread_mutex_lock(&arg->sgca->unit[pindex].mutex);
+
 			/* 3. On envoie la requête à l'avion */
 			if( send(arg->sgca->unit[pindex].socket, buffer, count/sizeof(char), 0) <= 0 ){
 				printf("{udp_cterm}{com}(%d)      Cannot send request to plane\n", index);
@@ -445,6 +438,9 @@ void* manageCtrlTerm(void* THREADABLE_ARGS){
 			/* 1. Réception de la réponse */
 			count = recv(arg->sgca->unit[pindex].socket, buffer, sizeof(char), 0);
 
+			// libération socket
+			pthread_mutex_unlock(&arg->sgca->unit[pindex].mutex);
+
 			if( count != sizeof(char) ){
 				printf("{udp_cterm}{com}(%d)      Cannot get response from plane %d (%d)\n", index, count, (int) PLANE_LEN);
 				break;
diff --git a/plane/plane.c b/plane/plane.c
index d7c195a..2220bc5 100644
--- a/plane/plane.c
+++ b/plane/plane.c
@@ -337,12 +337,11 @@ void update(){
       /* [3] Gestion de la réponse
       =========================================================*/
       /* 1. On prépare la réponse */
-      buffer[0] = 0x55;
-      buffer[1] = request.flags;
+      buffer[0] = request.flags;
       printf("Response flags : %d\n", request.flags);
 
       /* 2. Envoi de la réponse */
-      if( send(commu_socket, buffer, sizeof(char)*2, 0) <= 0 ){
+      if( send(commu_socket, buffer, sizeof(char), 0) <= 0 ){
           printf("Cannot send response\n");
       }