diff --git a/src/disaster_vehicle.h b/src/disaster_vehicle.h
--- a/src/disaster_vehicle.h
+++ b/src/disaster_vehicle.h
@@ -39,6 +39,7 @@ enum DisasterSubType {
 struct DisasterVehicle FINAL : public SpecializedVehicle<DisasterVehicle, VEH_DISASTER> {
 	SpriteID image_override;            ///< Override for the default disaster vehicle sprite.
 	VehicleID big_ufo_destroyer_target; ///< The big UFO that this destroyer is supposed to bomb.
+	byte flags;                         ///< Flags about the state of the vehicle, @see AirVehicleFlags
 
 	/** For use by saveload. */
 	DisasterVehicle() : SpecializedVehicleBase() {}