Looking Ahead to Flying Beyond Visual Line of Sight
What is BVLOS? BVLOS means Beyond Visual Line of Sight operations for drones. BVLOS is the natural progression for commercial drone operations, but before it can take off the FAA will need to make it safe, so until then everyone is in a holding pattern. The limitation to Visual Line of Sight (VLOS) or Extended Visual Line of Sight (EVLOS) is part of the reason multirotors dominate the market today; there’s little demand for long-range fixed wing drones without the FAA’s regulations for BVLOS. So, when BVLOS happens, the question is with what regulation, which technical leaps, and where upgrades need to occur to put your drone into the national airspace?
The answer is there are three core requirements before wide adoption of BVLOS operations can be adopted: detect-and-avoid technology, robust communication systems, and airworthiness certification.
Detect and Avoid
One of the core tenets of flight is being able to “see and avoid” other aircraft. Nobody wants a collision in mid-air. Pilots are trained to constantly scan the sky within line of sight even as they monitor their aircraft’s instruments. However, for drone operators, they’re physically removed from the unmanned aerial system (UAS) itself, adding an extra degree of difficulty and complexity in spotting other aircraft. If UAS are going to fly beyond visual line of sight, how can we ensure that they’ll be able to execute the basic practice of seeing and avoiding other aircraft?
Per codified FAA mandate, a remote pilot must always know the unmanned aircraft’s (UA) location, determine the UA’s attitude, altitude, and direction of flight, observe the airspace for other air traffic hazards, and determine that the UA does not endanger the life or property of another.
There are a number of solutions that are undergoing development to ensure detect-and-avoid capabilities of UAS. Methods include using a ground-based network of active sensors, utilizing onboard sensors, or subscribing to a traffic management platform. The key distinction is that aircraft in the national airspace (NAS) must achieve a ‘well clear’ status from other aircraft. The definition of ‘well clear’ quantitatively is not defined by the FAA, though NASA is currently working on defining this term in quantitative terms.
To maintain BVLOS flight for UAS, detect-and-avoid technology needs to be clearly defined and implemented within UAS. There must be a predictable outcome for when encounters between UAS and other entities in the NAS occur. With a predictable, automated outcome for these encounters, detect-and-avoid technology can be successfully implemented as drones move into the BVLOS realm and the NAS.
Robust Communication Systems
Technically, there are two major requirements for the communication systems of UAS going BVLOS. First, there must be absolutely reliable communication links between the operator and the drone. Loss of link can become exponentially more dangerous when the operator’s area of responsibility is beyond their actual line of sight. Second, UAS need to be able to communicate with other entities in the NAS—as a part of the detect-and-avoid requirement we talked about previously. Finally, beyond the technical components, communication systems will have to meet the minimum requirements for BVLOS communications as mandated by the FAA. To date, the FAA has not implemented regulations for communication systems, however RCTA SC-228 is currently working on the Minimum Operational Performance Standards to define those regulations.
To fulfill the technical requirements, there are three approaches to implementing communication systems. We can utilize satellite communications (SatCom), cellular communications (CellCom), or point to point RF. To assess these options, we establish its reliability, its cost, and its range.
SatComs are the choice for purely unlimited range. The go-to communication systems for BVLOS operations by the military, SatComs removes operational constraints with regards to distance. However, from a commercial standpoint, SatComs are also the most expensive option. Depending on the amount of data being transmitted back and forth, SatComs can scale up quickly into being unviable in regards to cost for the commercial sector. Reliable, unlimited range, but expensive.
CellComs utilize existing cellular phone networks to operate a UAS’ BVLOS communications on. This idea is becoming increasingly popular as the infrastructure already exists and data rates can quickly be adapted. Just like SatCom, you need to determine the bandwidth requirements and data rates. This quickly raises the effective cost of some operations such as real-time video streaming. Finally, CellComs are bound by the coverage area provided by the cellular infrastructure. If you don’t have bars on your phone, you probably won’t have communications for your drone.
Finally, point to point RF already represents the defacto method for controlling your drone. Essentially, to make drones BVLOS viable with point to point RF communication, you need to upgrade the radios for extended range and operation. The cost of which is expensive up front but does not incur any on-going data transmission charges. This allows for the most utility and flexible mission parameters as determining variables in communication are all on internal systems—not networks. This is Altavian’s preferred method of utilizing communications for BVLOS.
Perhaps the most daunting challenge to BVLOS operations is proving that your aircraft passes an airworthiness certification. Whether you’re piloting a 5-pound drone remotely or a Boeing 747, the FAA will regulate and certify airworthiness.
The FAA enforces airworthiness on two fronts: certifying the vehicle has an airworthiness certification and certifying that it is in airworthy condition. To certify an aircraft as airworthy, there are a number of certifications that must happen prior. First is Type Certification. Type Certification means that the aircraft is properly designed with regards to all its characteristics. Following the Type Certification is the Production Certification. This certification ensures that the manufacturer can competently produce all components of the aircraft to the specifications of the Type Certification. With a Production Certification, combined with Type Certification, any aircraft a manufacturer produces adhering to those parameters will be certified Airworthy.
The difficulty for BVLOS operations is that the FAA has not prescribed airworthiness in regulation for unmanned aircraft. They are tasked with either forcing this new category to comply with manned standards and regulations or creating a new set of standards from scratch. As development and progress continue by NASA, the FAA, and the UAS industry, hopefully these standards and regulations will become implemented to allow for regular BVLOS operations.