Second Century

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The word “autonomous” is increasingly making it's way into aviation vocabulary. Often in relation to drones or (e)VTOL aircraft with the capability to fly without a pilot on board. Thereby lowering the costs of operating these aircraft.

While lowering the operational costs is a popular argument for autonomous flying, it is not the one this article will discuss. When it comes to operational flexibility and the accessibility of airports in relation to Regional Air Mobility (RAM), autonomous technologies have other benefits as well.

Flying to smaller airports

As stated in another article, RAM will have to compete with cars, trains and busses. This is because it will be focused on connecting smaller regional airports and communities over relatively shorts distances. To and from places that people usually visit using ground transportation. NASA calculated that only 1,6% of the trips between 50 and 500 miles in the U.S. are executed by plane. They also calculated that 70% of the American air passengers travel via only 30 airports, while the U.S. has over 5.000 airports. RAM's business case is based on connecting people via these thousands of other airports.

The downside of operating from these smallers airports is that they often are not that well equipped when it comes to navigation beacons. They lack the accessibility that larger airports have during Instrumental Meteorological Conditions (IMC). Or simple put, during bad weather or at night these airports are not accessible. Not being able to land with low visibility or heavy rain is not acceptable when you want to operate profitable RAM-services.

Information autonomy

Autonomous technology will make it possible for RAM-operators to cope with the limitations of the smaller airports. And I don't mean autonomy in the sense that an aircraft needs to be able to land all by itself, like the Garmin Autoland system can. What I do mean is a more basic (but very important first step) form of autonomy: the aircraft, and the person operating the aircraft, being autonomous in the acquiring the right information to execute the flight.

During a VFR-flight (based on Visual Flight Rules) the pilot already has this information autonomy. He or she doesn't need any guidance from ground-based systems or people to safely execute the flight. Based on looking outside and crosschecking what they see with the information on charts and maps (digital or analog), they have all the information they need. No radio beacons, instrument landing systems or ATC required. ATC is often contacted, but this is usually for additional information, not because it is a necessity.

To perform an IFR-flight (based on Instrument Flight Rules and required to operate an economically viable airline) pilots have to depend on ground-based systems. Radio beacons such as VOR's and DME's for navigation purposes, an Instrument Landing System (ILS) for landing and ATC for separation from other aircraft.

Global Navigation Satellite Systems (GNSS) like GPS, Glonass and Galileo are important in making the aircraft operate independently from ground based systems. By using a GNSS the pilot can see the aircraft's location on a map, together with the location of airports. It is able to navigate to those airports and land (Garmin's cockpit systems have the ability to create a virtual ILS). All without using ground equipment. It is no surprise that Garmin, a manufacturer of products that all have GPS-functionality at its core, introduced an autoland system.

You could argue that relying on satellite systems is not being fully autonomous. It is often not precise enough and the GNSS-signal can be manipulated. Even tough I agree, for making RAM-operations possible at small airports it is an important piece of equipment.

Vision-based landing

Fortunately, more technology is being developed to assist future aircraft with autonomous flying. One important technology that is currently under development is Xwing's vision-based landing system. It is specifically developed to improve the accessibility of small airports. The company states that “fewer than 60 airports in the U.S. have a CAT III approach, and less than 20% of U.S. airports have an ILS approach at all”. So 80% of the American airports don't have a precision landing system, limiting the possibilities of landing during IMC using current technology.

While using a GNSS-system still depends on an external source, the satellites, the on-board vision-based system is truly independent. To be able to land in IMC you need more than front-facing camera to create the vision. You need something that can look through the fog and clouds. To do that, Xwing installs sensor pods on both wings of their Cessna Caravan aircraft. The pods scan the area around the aircraft to create enhanced situational awareness for the operator of the aircraft.

At the moment, the operator of the aircraft is still a person. Xwing uses their Cessna Caravans to fly short haul cargo flights while testing their equipment at the same time. They operate around 400 flights a week and use the acquired data to improve their technology. Working their way towards a system that is certified to operate fully autonomously.

Fully autonomous flying

Xwing's vision-based landing system is part of their larger Superpilot autonomy stack. This technology aims to make full autonomous flying possible. So without the input of any person. The video below was recorded during a fully autonomous flight from Xwing's Cessna Caravan. It shows that Xwing is already quite far along on their journey to make autonomous flying an everyday reality.

Video: Xwing demonstration flight

Xwing's technology will unlock the commercial potential of thousands of airports worldwide without governments having to invest in airport equipment. Thereby unlocking RAM's potential at the same time.

Aviation is more than one aircraft

Even though Xwing is making ground-breaking progress on the development of autonomous flying on an aircraft level, there is still more to be done to facilitate autonomous flying on a larger scale. To make sure several autonomously flying aircraft can safely operate in a single airspace, ATC-services have to develop as well.

Providing separation during IFR-flights is currently to a large extend based on voice communication. Yes, air traffic controllers have sophisticated radar systems to see where the traffic is. However, the communication with the operator of the aircraft is done vocally. Pilots also hear other pilots talk with ATC which is often also relevant to their own flight. It improves their situational awareness.

When it is a computer system operating the flight, as is the case with autonomous flying, these voice commands by controllers won't suffice. How does the controller know that the computer system in the aircraft has understood the message? A text message via a data link will work better. But what if the controller makes a typing error?

And, circling back to RAM-operations at small airports, what if the airport does not provide any ATC-services at all? How can you guarantee safe separation from other aircraft?

There is a lot to discuss about how ATC needs to change to facilitate autonomous flying and RAM. There are interesting developments going on in that field. However, that will be the topic of another article.