diff --git a/ROMFS/px4fmu_common/init.d-posix/rcS b/ROMFS/px4fmu_common/init.d-posix/rcS
index 2191d48e42..f7afafc143 100644
--- a/ROMFS/px4fmu_common/init.d-posix/rcS
+++ b/ROMFS/px4fmu_common/init.d-posix/rcS
@@ -65,7 +65,9 @@ fi
 
 
 # Use environment variable PX4_ESTIMATOR to choose estimator.
-if [ "$PX4_ESTIMATOR" = "ekf2" ]; then
+if [ "$PX4_ESTIMATOR" = "q" ]; then
+	param set SYS_MC_EST_GROUP 3
+elif [ "$PX4_ESTIMATOR" = "ekf2" ]; then
 	param set SYS_MC_EST_GROUP 2
 elif [ "$PX4_ESTIMATOR" = "lpe" ]; then
 	param set SYS_MC_EST_GROUP 1
diff --git a/ROMFS/px4fmu_common/init.d/rc.mc_apps b/ROMFS/px4fmu_common/init.d/rc.mc_apps
index 65329398ef..5c652e6a64 100644
--- a/ROMFS/px4fmu_common/init.d/rc.mc_apps
+++ b/ROMFS/px4fmu_common/init.d/rc.mc_apps
@@ -30,10 +30,18 @@ then
 	fi
 else
 	#
-	# EKF2
+	# Q estimator (attitude estimation only)
 	#
-	param set SYS_MC_EST_GROUP 2
-	ekf2 start
+	if param compare SYS_MC_EST_GROUP 3
+	then
+		attitude_estimator_q start
+	else
+		#
+		# EKF2
+		#
+		param set SYS_MC_EST_GROUP 2
+		ekf2 start
+	fi
 fi
 
 ###############################################################################
diff --git a/boards/omnibus/f4sd/init/rc.board_defaults b/boards/omnibus/f4sd/init/rc.board_defaults
index daae85b4cb..e26bffe55f 100644
--- a/boards/omnibus/f4sd/init/rc.board_defaults
+++ b/boards/omnibus/f4sd/init/rc.board_defaults
@@ -4,6 +4,12 @@
 #------------------------------------------------------------------------------
 
 
+# transition from LPE+Q to Q estimator (2019-06-05)
+if param compare SYS_MC_EST_GROUP 1
+then
+	param set SYS_MC_EST_GROUP 3
+fi
+
 
 if [ $AUTOCNF = yes ]
 then
@@ -11,7 +17,7 @@ then
 	param set CBRK_IO_SAFETY 22027
 
 	# use the Q attitude estimator, it works w/o mag or GPS.
-	param set SYS_MC_EST_GROUP 1
+	param set SYS_MC_EST_GROUP 3
 	param set ATT_ACC_COMP 0
 	param set ATT_W_ACC 0.4000
 	param set ATT_W_GYRO_BIAS 0.0000
diff --git a/src/lib/systemlib/system_params.c b/src/lib/systemlib/system_params.c
index f0041bef89..2b916f06e6 100644
--- a/src/lib/systemlib/system_params.c
+++ b/src/lib/systemlib/system_params.c
@@ -102,9 +102,8 @@ PARAM_DEFINE_INT32(SYS_RESTART_TYPE, 2);
  *
  * @value 1 local_position_estimator, attitude_estimator_q (unsupported)
  * @value 2 ekf2 (recommended)
+ * @value 3 Q attitude estimator (no position)
  *
- * @min 1
- * @max 2
  * @reboot_required true
  * @group System
  */