Well, not exactly. In case of an engine failure, the system still has power from the batteries to control the actuator and glide the plane (in fact, it will automatically switch to flying at the best glide speed to extend it's range) to a safe landing, whether it's at an airport or in a field. But if you are over some trees, mountains, or somewhere else where a landing is impossible (which is a problem in today's planes too) the parachute is a final backup. the parachute is also the backup in case of a complete system failure