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Urban Air Mobility Glossary

Our UAM Glossary is a collaborative effort from many industry experts.

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Beyond Visual Line of Sight (BVLOS)

Beyond Visual Line of Sight (BVLOS) denotes the ability to conduct unmanned aerial vehicle (UAV) operations without the need for pilots to maintain constant visual proximity to the UAVs at all times. The current BVLOS Unmanned Aerial Systems (UAS) operations are being trialled within controlled segregated environments such as construction, infrastructure, oil and gas industries, to mitigate risks associated with not flying under visual flight rules (VFR).  


BVLOS operations

Under BVLOS, the pilots are able to control drones and other future flight aircraft from ground stations and through onboard visual devices. This provides the pilot with the ability to monitor the surroundings of the drones for approaching air traffic to avoid mid-air collisions. 


Various information such as speed, direction of flight, attitude (orientation relative to the Earth's horizon) and altitude (vertical height) are relayed to the pilot through telemetry links. In order to fly drones BVLOS, pilots have to undergo extra training where they cover concepts of flight performance and planning, navigation of unmanned flights and meteorology.


Flying BVLOS enables drone operations to be conducted more efficiently gaining access to a greater range of distance. Drones used for surveillance or search and rescue operations can be deployed for a longer amount of time in comparison to flying in visual line of sight (VLOS). It can also allow for the operator to be in an off-site location.


There are several occasions where accidents or incidents occur in regions with dangerous terrains that can land humans in hazardous situations. With search and rescue for example, it can become time-consuming in locating missing people or an accident site.

The ability to fly drones BVLOS opens up an additional pathway to increase efficiency, time savings and successful life-saving operations. It is also anticipated that with the ability to fly BVLOS, UAV operations can possibly replace traditional satellites and manned aircraft for aerial data collection. As drones can fly at low altitudes, they are at an advantage for high resolution data collection and imagery.

Developments in BVLOS

The current developments in BVLOS will allow for increased UAS operations within restricted/controlled airspace. 


To illustrate, the Civil Aviation Authority (CAA) within the United Kingdom (UK) has outlined a development pathway for UAV trials with BVLOS to be initially conducted within segregated airspace (i.e. reserved for specific users; may include unmanned aviation). Further trials will also be conducted within non-segregated representative environments and non-segregated target environments (built-up areas). 


The developments in BVLOS will prove to be advantageous for UAS operations within Advanced Air Mobility (AAM), including Urban Air Mobility (UAM) for the delivery of parcels and cargo for example. 

Sources and suggested reading 


  1. EU Regulations Updates -  Drone rules 

  2. What is visual line of sight as defined by CAA (in real world terms)? -Drone Training 

  3. Beyond Visual Line of Sight (BVLOS): An Introductory Guide - Iris Automation

  4. Setting the path to drone deliveries and remote inspections: Making beyond visual line of sight drone operations commonplace - CAA

  5. Non-Segregated BVLOS -CAA

  6. What is BVLOS, and why is it important for drone industry? –  Geospatial World. 

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