An at least temporarily unmanned aircraft or spacecraft which travels through a controlled airspace in accordance with a previously cleared flight plan, in which aircraft or spacecraft a C2 link, via which the aircraft or spacecraft can be or is controlled, is least temporarily unavailable, and which aircraft or spacecraft is provided with a sensor device which is configured to identify a situation being at least one of dangerous or an emergency, which makes it necessary to deviate from the cleared flight plan, wherein the aircraft or spacecraft has a control device which is configured to independently use a wireless data link to a supervisory authority in order to agree to a changed flight plan containing at least one change.