diff --git a/msg/estimator_status.msg b/msg/estimator_status.msg
index 6bbcd59eb6..cda4844089 100644
--- a/msg/estimator_status.msg
+++ b/msg/estimator_status.msg
@@ -17,3 +17,18 @@ uint16 gps_check_fail_flags     # Bitmask to indicate status of GPS checks - see
 # 6 : maximum allowed vertical position drift fail
 # 7 : maximum allowed horizontal speed fail
 # 8 : maximum allowed vertical velocity discrepancy fail
+uint16 control_mode_flags	# Bitmask to indicate EKF logic state
+# 0 - true if the filter tilt alignment is complete
+# 1 - true if the filter yaw alignment is complete
+# 2 - true if GPS measurements are being fused
+# 3 - true if optical flow measurements are being fused
+# 4 - true if a simple magnetic yaw heading is being fused
+# 5 - true if the horizontal projection of magnetometer data is being fused
+# 6 - true if 3-axis magnetometer measurement are being fused
+# 7 - true if synthetic magnetic declination measurements are being fused
+# 8 - true when the vehicle is airborne
+# 9 - true when the vehicle motors are armed
+# 10 - true when wind velocity is being estimated
+# 11 - true when baro height is being fused as a primary height reference
+# 12 - true when range finder height is being fused as a primary height reference
+# 15 - true when range finder height is being fused as a primary height reference