diff --git a/mav_msgs/CMakeLists.txt b/mav_msgs/CMakeLists.txt
index 7783849..66f3520 100644
--- a/mav_msgs/CMakeLists.txt
+++ b/mav_msgs/CMakeLists.txt
@@ -8,6 +8,7 @@ find_package(Eigen REQUIRED)
 include_directories(${EIGEN_INCLUDE_DIRS})
 
 add_message_files(
+  DIRECTORY msg
   FILES
   CommandAttitudeThrust.msg
   CommandMotorSpeed.msg
@@ -18,6 +19,12 @@ add_message_files(
   MotorSpeed.msg
 )
 
+add_service_files(
+  DIRECTORY srv
+  FILES
+  SetFlightMode.srv
+)
+
 generate_messages(DEPENDENCIES std_msgs geometry_msgs)
 
 catkin_package(
diff --git a/mav_msgs/srv/SetFlightMode.srv b/mav_msgs/srv/SetFlightMode.srv
new file mode 100644
index 0000000..e1d48b0
--- /dev/null
+++ b/mav_msgs/srv/SetFlightMode.srv
@@ -0,0 +1,19 @@
+# This service is used to switch the flight mode.
+
+uint8 MODE_INACTIVE=0
+uint8 MODE_PREARM=1
+uint8 MODE_MANUAL=2
+uint8 MODE_ATTITUDE=3
+uint8 MODE AUTO=4
+uint8 MODE_RTL=5
+
+uint8 request_mode
+
+---
+
+uint8 FAILURE_UNDEFINED=0
+uint8 FAILURE_LOCALIZATION_NOT_AVAILABLE=1
+# ... TODO fill the failure modes in
+
+uint8 resultant_mode
+uint8[] failure_reasons # A list of reasons why the mode change failed.