diff --git a/msg/vehicle_constraints.msg b/msg/vehicle_constraints.msg
index 9ba6390aa9..55f3a69117 100644
--- a/msg/vehicle_constraints.msg
+++ b/msg/vehicle_constraints.msg
@@ -6,6 +6,7 @@ float32 speed_xy	# in meters/sec
 float32 speed_up	# in meters/sec
 float32 speed_down	# in meters/sec
 float32 tilt    # in radians [0, PI]
+float32 min_distance_to_ground # in meters
 
 int8 GEAR_DOWN = -1
 int8 GEAR_UP = 1