This document defines and compares Visual Line of Sight (VLOS), Extended Visual Line of Sight (EVLOS), and Beyond Visual Line of Sight (BVLOS) drone operations. VLOS requires continuous unaided visual contact between the pilot and drone. EVLOS allows limited flight beyond the pilot's visual line using trained observers to assist. BVLOS has no visual line of sight requirement and is more difficult to obtain approval for due to greater risks without "see and avoid" capability.

1. Beyond Visual Line of
Sight (BVLOS)
60-60 Advance – Dr Karthigeyan

2. VLOS
• The terms Visual Line of Sight (VLOS), Extended Visual Line of Sight
(EVLOS) and Beyond Visual Line of Sight (BVLOS) are used regularly by
the drone industry, but what do they mean? And why do you need to
know these terms when considering a drone programme?
• It’s critical to know what these terms mean so that you can mitigate
the risks to the business or organisation, by anticipating and
addressing the correct procedures for each type of flight operation.

3. One of the most globally misunderstood rules in drone operations is the requirements to operate an Unmanned
Aircraft (also known as Unmanned Air Vehicle (UAV) or Remotely Piloted Aircraft (RPA) within VLOS.
Visual Line of Sight (‘VLOS’) operations are a type of UAS operation in which the remote pilot maintains
continuous, unaided visual contact with the unmanned aircraft. In its simplest term, the aircraft must always be
visible to the pilot.
This allows the remote pilot to control the flight path of the unmanned aircraft in relation to other aircraft,
people, and obstacles for the purpose of avoiding collisions. The aircraft may not be flown behind trees,
buildings, or other obstacles.
Unaided visual contact means natural eyesight, with prescription glasses or sunglasses; however, binoculars,
telescopes etc are not a permitted method for VLOS flights.
The Regulations in the UK and Europe create an offence to operate an Unmanned Aircraft outside of permitted
rules and procedures; a breach of the rule carries significant penalties.

5. • What is EVLOS (Extended Visual Line of Sight)?
• Extended Visual Line of Sight operations ('EVLOS') allows flight Beyond
Visual Line of Sight of the Remote Pilot by using ‘trained
observers’. Trained observers are used to comply with the separation and
collision avoidance responsibilities of the operator.
• Fundamentally, EVLOS is an operational method where a pilot is always
present on a location with one or more external observers keeping the UAV
in their line of sight.
• At the same time, these observers communicate critical flight information
through radio to assist the pilot in maintaining a safe distance from other
air users, both manned and unmanned, as well as structures, terrain and
other hazards.

6. • EVLOS operations require special permission from your respective Aviation
Authority. Permission for EVLOS operations can usually be obtained
through a straightforward approval process in most countries.
• EVLOS is not location-specific, unlike BVLOS, with observers who can be
trained in-house or through a professional training organisation as required.

7. • What is BVLOS (Beyond Visual Line of Sight)?
• BVLOS (sometimes also called BLOS), means ‘Beyond Visual Line of Sight'
operations. This is where the flying of a drone is without
a pilot maintaining visual line of sight on the aircraft at all times. Instead,
the pilot operates the UAV using Remote Pilot Station (RPS) /
Ground Control Station (GCS) instruments.
• An unmanned aircraft being operated BVLOS no longer has the protection of
the pilot or observer to avoid terrain, obstacles or other aircraft (called ‘See
and Avoid’ or ‘Detect and Avoid’ (DAA)). BVLOS operations require
extremely careful planning by operators with a framework process in place
with most Aviation Authorities, in which to justify and explain the
procedures to be followed during the flight.

8. • While operations outside of a pilot’s line of sight have been available for
some time under BVLOS provisions, the pilot training requirements are
generally arduous, and approvals are issued on a location-by-location,
case-by-case basis.
• Obtaining an approval to fly BVLOS, while hugely valuable, is a challenging
task.
• In May 2020, with the world in the grips of the global COVID 19
pandemic, a team worked in partnership with drone deliveries
provider Skyports, on a ground-breaking, first of a kind, BVLOS medical
drone delivery trial.