The Difference Between BVLOS, VLOS, and EVLOS
March 23, 2023
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The Difference Between BVLOS, VLOS, and EVLOS

To stay safe when using unmanned aerial vehicles (UAVs), the acronyms BVLOS, VLOS, and EVLOS are essential.

BVLOS stands for Beyond Visual Line of Sight, VLOS for Visual Line of Sight, and EVLOS for Extended Visual Line of Sight.

BVLOS means you (the operator) are flying your drone out of sight range.

With VLOS and EVLOS, you can see your drone as you fly. But EVLOS requires a trained observer to help you.

Each line of sight has specific regulations you must follow when operating a drone.

If not, it could land you in trouble with the authorities.

So, to help you mitigate risk and understand the correct procedures for each line of sight, here are their differences.

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Differences Between VLOS, EVLOS, and BVLOS

This is how these mission types differ: 

VLOS( Visual Line of Sight)

You can always see the UAV when flying with your unaided eyesight. Unaided vision entails using your natural vision, prescription glasses, or sunglasses, but not binoculars or telescopes.

With VLOS, you can control the drone to avoid colliding with people, aircraft, or trees. However, there are restrictions as you should never fly behind obstructions like trees or buildings.

For example, you may use VLOS to fly a drone in a park or to take aerial images or movies.

EVLOS (Extended Visual Line of Sight)

You can operate the drone beyond your visual range for this mission type. 

But you’ll need the help of trained visual observers.

The trained observers keep a continual line of sight on the drone and relay its location to you via a radio, or other 2 way communication.

This assists you in maintaining a safe distance from other aircraft, UAVs, buildings, trees, or people using DAA (Detect and Avoid).

For example, you can use EVLOS to fly a drone while doing search and rescue in undiscovered terrains such as mountains or forests, with an observer stationed at a higher level, like from a helicopter.

BVLOS (Beyond Visual Line of Sight)

BVLOS, also known as Beyond Line of Sight (BLOS), allows you to operate the UAV while it is not in your line of sight and there is no visual observer.

To control the drone securely, you rely on communication and sensing tools and technology such as the Remote Pilot Station (RPS) or Ground Control Station (GCS).

For example, you can use BVLOS to fly a drone and conduct inspections or aerial surveys of land or bodies of water.

But, you must obtain A Special Flight Operations Certificate (SFOC) from Transport Canada.  on a case-by-case basis.

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Advantages and Disadvantages of VLOS, EVLOS and BVLOS

Mission type




Easy to operate, as you can see the drone while you fly it, and the operation can be conducted by a single pilot.

Limited range of operation since you must have the drone in sight at all times, even on hazy, misty, or snowy days.


Has greater flexibility in flight patterns. You can operate the UAV further away from the person at the controls as you have an observer to adjust the drone’s flight path

Requires more manpower. You need a trained observer to always have the drone in their line of vision, which can increase operational costs and logistics.


You can operate the drone over a higher altitude than VLOS and EVLOS, as you rely on technology to fly it safely.

Requires specialized training for the pilot to ensure they can use the technology available safely.

You must have special permission from your respective Aviation Authority before operating the UAV.

Future of BVLOS

Mordor Intelligence projects that the BVLOS drone market will grow by more than 10% by 2027.

BVLOS allows more efficient and effective operations such as long-distance parcel delivery, agricultural monitoring, surveying, and search and rescue.

However, for this to happen, several of the cutting-edge technologies detailed below will be helpful in future BVLOS operations:

  • High bandwidth communications like satellite-based systems 5G. It will help transmit commands and data faster between the drone and the ground station.
  • Advancements in DAA technology. BVLOS requires no professional observers and instead depends on technology to detect and avoid obstructions. The disadvantage is that an operator cannot avoid these barriers in real time. But, if DAA technology advances, BVLOS may be able to recognize and avoid obstacles in real time in the future.
  • Integration with more advanced technologies. BVLOS works efficiently by integrating various technologies like AI, sensors, and systems. As these technologies continue to advance, the potential for BVLOS will increase.
  • Clear regulations by the Aviation Authority. As aviation standardizes regulations on how to use BVLOS, more commercial and industrial applications may adopt it.

Overall, the future of BVLOS in UAVs is very exciting, and we can expect to see many advancements and new applications in the coming years.

However, it is important to note that safety and regulatory compliance will remain critical factors in developing and adopting this technology.

At Coastal Drone, we have the expertise to ensure you are capable of operating your drone in any visual line, contact us for professional and detailed drone pilot training.

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