Unmanned Freight Operations

"Controlling freight aircraft from the ground has several benefits," explained Annette Temme from the DLR Institute of Flight Guidance. "For example, crews can be deployed more flexibly on the ground, as they do not need to actually travel on long-haul flights, but can operate the aircraft from a single location." This allows extended flight times and a more balanced distribution of workload.

In Project UFO, the DLR Institutes of Flight Guidance, Flight Systems, DLR Institute of Communications and Navigation and DLR Institute of Aerospace Medicine, together with the DLR Institute of Air Transportation Systems, accepted one of the key challenges for the operation of unmanned freight aircraft: to integrate these into the existing, conventional air transport system. To do this, they devised specific solutions for the airspace managed by air traffic control. This resulted in three different scenarios for which researchers then developed and validated new support systems, procedures and technologies for air traffic controllers and pilots.

The scenarios

The three application scenarios that were developed include freight transport between two manufacturing sites, long-haul freight transport and the transport of relief goods. These three examples primarily differ in terms of the size of aircraft used and the distances covered. Temme explains the selection: "The chosen scenarios cover a wide range of different airspace integration issues."

In addition to the technical challenges of communication, navigation and surveillance, as well as monitoring the condition of the unmanned aerial vehicle, the investigation also considered the human factor and developed ideas to help pilots and air traffic controllers. "During a workshop with Deutsche Flugsicherung, we discovered that the surveillance tasks of a pilot on the ground generally resemble the current remit of an air traffic controller," said Temme, reporting on the other results.

Integration into airspace

The three scenarios have different requirements in terms of airspace integration. For the transport of relief goods scenario, one surveillance possibility is to separate the airspace by means of special corridors, similar to those for manned relief missions. The aircraft are guided along fixed routes, separated from the surrounding air traffic. When transporting factory goods, both certification and authorisation for a special transport task (EASA SORA SPECIFIC) need to be considered, as well as integration into the air transport system. Long-haul freight transport, however, can only be integrated into conventional air transport system. In this case, sector-less guidance would be conceivable, whereby an air traffic controller monitors unmanned aircraft over a longer stretch of the route. Specially trained air traffic controllers could supervise the unmanned aircraft. These would be in contact with a pilot on the ground, who would carry out the air traffic controllers' instructions accordingly.

Airport integration

When approaching the airport, unmanned aircraft are integrated into the arrival and departure sequence, taking account of their specific requirements. At busy airports, in particular, conventional air traffic should not be adversely affected by unmanned freight aircraft. Researchers therefore enhanced and tested the air traffic control support systems so that air traffic controllers can recognise the characteristics of unmanned aircraft. In one example, they used established towing procedures. As with a normal commercial aircraft, the unmanned freight aircraft is handed over to the tractor driver by the ground control station, towed from the runway, unloaded and reloaded and towed back to the runway, where it is handed over to the pilot.