diff --git a/sw/airborne/subsystems/ins/ins_int.c b/sw/airborne/subsystems/ins/ins_int.c
index 4e10c36e24..a1334f3874 100644
--- a/sw/airborne/subsystems/ins/ins_int.c
+++ b/sw/airborne/subsystems/ins/ins_int.c
@@ -191,7 +191,7 @@ static void baro_cb(uint8_t __attribute__((unused)) sender_id, const float *pres
     ins_ltp_pos.z   = POS_BFP_OF_REAL(vff_z);
   }
   else {
-    ins_baro_alt = pprz_isa_height_of_pressure(*pressure, ins_qfe);
+    ins_baro_alt = -pprz_isa_height_of_pressure(*pressure, ins_qfe);
     vff_update(ins_baro_alt);
   }
   INS_NED_TO_STATE();
diff --git a/sw/airborne/subsystems/ins/ins_int.h b/sw/airborne/subsystems/ins/ins_int.h
index c9a861be8b..9de003ca96 100644
--- a/sw/airborne/subsystems/ins/ins_int.h
+++ b/sw/airborne/subsystems/ins/ins_int.h
@@ -50,7 +50,7 @@ extern struct NedCoor_i ins_gps_speed_cm_s_ned;
 
 /* barometer                   */
 #if USE_VFF
-extern float ins_baro_alt;  ///< altitude calculated from baro in meters
+extern float ins_baro_alt;  ///< altitude calculated from baro in meters (z-down)
 extern float ins_qfe;
 extern bool_t  ins_baro_initialised;
 #endif
diff --git a/sw/airborne/subsystems/ins/ins_int_extended.c b/sw/airborne/subsystems/ins/ins_int_extended.c
index 9c6677bd12..3470095461 100644
--- a/sw/airborne/subsystems/ins/ins_int_extended.c
+++ b/sw/airborne/subsystems/ins/ins_int_extended.c
@@ -214,7 +214,7 @@ static void baro_cb(uint8_t __attribute__((unused)) sender_id, const float *pres
     ins_ltp_pos.z   = POS_BFP_OF_REAL(vff_z);
   }
   else {
-    ins_baro_alt = pprz_isa_height_of_pressure(*pressure, ins_qfe);
+    ins_baro_alt = -pprz_isa_height_of_pressure(*pressure, ins_qfe);
     vff_update_baro(ins_baro_alt);
   }
   INS_NED_TO_STATE();