Unmanned aerial vehicles have become extremely useful in recent years. The many popular applications include agricultural surveillance, mail delivery, photographing and coastal surveillance. However, a major limitation remains operations beyond visual line of sight (BVLOS).
In these few paragraphs, we’ll look at the matter with flying BVLOS.
What is BVLOS?
Beyond Visual Line of Sight (BVLOS) is a legal requirement by many authorities which restricts the pilot from flying a drone when not physically able to see it. Some authorities, e.g. Europe, even additionally limit the LOS (Line of Sight) distance to 500m and its height to 400’.
Well, why not fly beyond LOS limitations?
There are several risks associated with flying when the pilot is no longer able to see his drone:
Risk # 1: Airborne collision. The risk with the most severe possible consequences is an airborne collision with manned air traffic. It can easily be envisaged that a 10kg device colliding with an airliner traveling at 300km/h, may cause serious damage and threaten the safety of the souls on board. Authorities seem to think that as long as a drone pilot keeps his craft in sight, there would be an added level of safety in that the drone can be maneuvered clear of an oncoming manned aircraft. Take the Gatwick case study as an example: On 19 and 20 December 2018, Gatwick airport in the UK was closed on and off when drones were spotted over the runways. This caused a major disruption but the authorities had no choice due to the risk pf airborne collision. (By the time of writing this article, the culprits have not been nailed yet).
Parallel to the above, large flight distances also harbor an increased risk of infringement of restricted airspace.
Risk # 2: Public/ drone interaction. Considering the risk of personal injury, it is highly desirable that the public does not interact with drones. This is a major issue for those involved with drone delivery projects- when delivering BVLOS, the pilot is not present to keep a watchful eye over the release if the package. Several solutions are employed, including to hoist the package down from a safe height which ensures separation between the drone and the public.
Risk # 3: Loss of connection. Control units are limited in effective ranges which might vary between a few meters and several kilometers. If control is lost, a drone crash might ensue causing injuries and damage. For this reason, drones are often equipped with a return-to-launch function that kicks in as soon as certain preset parameters, including loss of contact with the control unit, is exceeded.
So, how does that influence my flying on the local school football field?
Well, the short answer is that BVLOS is a firm rule that may not ever be transgressed, except with regulatory permission- and such permission is rarely attained. Over the past year or so, 99% of the applications to the FAA to operate BVLOS have failed.
In addition, many authorities have defined BVLOS even further. For example, in Europe, the limits are set at 500m and 400’.
It is worth mentioning the concept of “First Person View” (FPV) here. Drones fitted with cameras may transmit the image seen to a screen or 3-D goggles – an exhilarating experience! However, the regulation expressly excludes FPV as a replacement for the pilot’s eyes in terms of complying with the BVLOS rule.
System Design for BVLOS
Authorities will only consider approving BVLOS applications if the system is designed to fully alleviate the above mentioned risks. The design should provide for:
- Effective GNSS navigation and track monitoring on screen.
- Return-to-Launch (RTL) function, to that can be manually activated, or automatically if preset requirements are no longer satisfied. For example, a particular block of airspace may be pre-programmed into the system, and if the drone finds itself outside of the limitations, it would return to the point of launch (or to a suitable predefined way point).
- FPV streaming via on-board camera.
- A suitable on-board collision avoidance system, such as TCAS (manned aircraft are normally so equipped as well).
- Lastly, working in conjunction with TCAS, an All-Weather Sense and Avoid System (AWSAS) based on Automatic Dependent Surveillance Broadcast (ADS-B) technology is needed.
It can easily be appreciated that many links on different frequencies are required to enable all the above mentioned functions in addition to the regular control function!
Will the Last Frontier eventually be crossed?
Without a doubt, yes, it will. This might take some time, though. Although the technology has been developed already, the regulators are generally slow to generate the parameters within which BVLOS will become common.