diff --git a/conf/airframes/examples/Twinstar_energyadaptive.xml b/conf/airframes/examples/Twinstar_energyadaptive.xml
index d0f83f5147..972093d111 100644
--- a/conf/airframes/examples/Twinstar_energyadaptive.xml
+++ b/conf/airframes/examples/Twinstar_energyadaptive.xml
@@ -54,6 +54,7 @@ twog_1.0 + aspirin + ETS baro + ETS speed
       <define name="BARO_ETS_ALT_SCALE" value="0.3"/>
       <define name="BARO_ETS_SYNC_SEND"/>
     </load>
+    <load name="baro_sim.xml"/>
     <load name="digital_cam.xml">
       <define name="DC_SHUTTER_LED" value="5"/><!-- led4:aux led5:camsw-->
     </load>
diff --git a/conf/firmwares/subsystems/shared/baro_board.makefile b/conf/firmwares/subsystems/shared/baro_board.makefile
index 012f3326b8..7bea12cf0b 100644
--- a/conf/firmwares/subsystems/shared/baro_board.makefile
+++ b/conf/firmwares/subsystems/shared/baro_board.makefile
@@ -125,8 +125,9 @@ endif
 #
 # add it for simulators
 #
-sim.srcs += $(SRC_BOARD)/baro_board.c
-jsbsim.srcs += $(SRC_BOARD)/baro_board.c
+# only NPS for now...
+#sim.srcs += $(SRC_BOARD)/baro_board.c
+#jsbsim.srcs += $(SRC_BOARD)/baro_board.c
 nps.srcs += $(SRC_BOARD)/baro_board.c
 
 
diff --git a/conf/modules/baro_sim.xml b/conf/modules/baro_sim.xml
new file mode 100644
index 0000000000..ca694bb582
--- /dev/null
+++ b/conf/modules/baro_sim.xml
@@ -0,0 +1,22 @@
+<!DOCTYPE module SYSTEM "module.dtd">
+
+<module name="baro_sim" dir="sensors">
+  <doc>
+    <description>
+      Simulated barometer.
+      Sends the BARO_ABS ABI message with gps.hmsl converted to absolute pressure.
+    </description>
+  </doc>
+
+  <header>
+    <file name="baro_sim.h"/>
+  </header>
+  <init fun="baro_sim_init()"/>
+  <periodic fun="baro_sim_periodic()" freq="10."/>
+
+  <makefile target="sim|jsbsim">
+    <file name="baro_sim.c"/>
+    <define name="USE_BARO_BOARD" value="FALSE"/>
+  </makefile>
+
+</module>
diff --git a/sw/airborne/boards/pc_sim.h b/sw/airborne/boards/pc_sim.h
index c15970eb21..c3583ebabd 100644
--- a/sw/airborne/boards/pc_sim.h
+++ b/sw/airborne/boards/pc_sim.h
@@ -11,7 +11,8 @@
 
 #define DefaultVoltageOfAdc(adc) (1.0*adc)
 
-
+#ifndef USE_BARO_BOARD
 #define USE_BARO_BOARD 1
+#endif
 
 #endif /* CONFIG_PC_SIM_H */
diff --git a/sw/airborne/modules/sensors/baro_sim.c b/sw/airborne/modules/sensors/baro_sim.c
new file mode 100644
index 0000000000..0b58664a2d
--- /dev/null
+++ b/sw/airborne/modules/sensors/baro_sim.c
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2013 Felix Ruess <felix.ruess@gmail.com>
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/**
+ * @file baro_sim.c
+ *
+ * Simulate barometer pressure measurement using gps.hmsl
+ */
+
+#include "math/pprz_isa.h"
+#include "subsystems/gps.h"
+#include "subsystems/abi.h"
+
+#ifndef BARO_SIM_SENDER_ID
+#define BARO_SIM_SENDER_ID 1
+#endif
+PRINT_CONFIG_VAR(BARO_SIM_SENDER_ID)
+
+void baro_sim_init(void) {
+
+}
+
+void baro_sim_periodic(void) {
+  float pressure = pprz_isa_pressure_of_altitude(gps.hmsl / 1000.0);
+  AbiSendMsgBARO_ABS(BARO_SIM_SENDER_ID, &pressure);
+}
diff --git a/sw/airborne/modules/sensors/baro_sim.h b/sw/airborne/modules/sensors/baro_sim.h
new file mode 100644
index 0000000000..a78d3218fa
--- /dev/null
+++ b/sw/airborne/modules/sensors/baro_sim.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2013 Felix Ruess <felix.ruess@gmail.com>
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/**
+ * @file baro_sim.h
+ *
+ * Simulate barometer pressure measurement using gps.hmsl
+ */
+
+#ifndef BARO_SIM_H
+#define BARO_SIM_H
+
+/// new measurement every baro_sim_periodic
+#define BARO_SIM_DT BARO_SIM_PERIODIC_PERIOD
+
+extern void baro_sim_init(void);
+extern void baro_sim_periodic(void);
+
+#endif
diff --git a/sw/airborne/subsystems/ins/ins_alt_float.c b/sw/airborne/subsystems/ins/ins_alt_float.c
index b12c50b66f..6e0afeb916 100644
--- a/sw/airborne/subsystems/ins/ins_alt_float.c
+++ b/sw/airborne/subsystems/ins/ins_alt_float.c
@@ -193,7 +193,11 @@ void alt_kalman(float z_meas) {
   float SIGMA2;
 
 #if USE_BAROMETER
-#if USE_BARO_MS5534A
+#ifdef SITL
+  DT = BARO_SIM_DT;
+  R = 0.5;
+  SIGMA2 = 0.1;
+#elif USE_BARO_MS5534A
   if (alt_baro_enabled) {
     DT = BARO_DT;
     R = baro_MS5534A_r;