Understanding what Visual Line of Site (VLOS) is for use in drone surveys and inspection work.
The abbreviated term VLOS may only be four letters but it is of vital importance for the drone inspection work we provide for our customers. Much in the same way that VFR (Visual Flight Rules) is applied to manned aircraft, VLOS forms part of the regulations set out by the Civil Aviation Authority (CAA) for piloting an unmanned aerial vehicle (UAV) for drone inspection work.
By their nature, unmanned aerial vehicles do not have the pilot on board, rather they are controlled by remote control piloting. This means that a drone pilot/operator must always maintain visual line of sight on the drone during inspection flights. This line of sight must be unaided or enhanced using the likes of binoculars or thermal night vision goggles (for example).
VLOS is one of the most important rules in drone flight and is not reserved just for commercial drone services. VLOS rules apply for both commercial drone surveys and private/recreational drone use.
Potential Obstructions
Visual Line of Site is important and the pilot must keep constant observation on the drone mid flight, regardless of what obstacles may be in the flight path. This includes:
- Buildings
- Trees
- Hills
- Bridges
- Clouds
- Fog
Why is visual line of site so important?
There are four crucial considerations that require VLOS mid flight. It allows the pilot to monitor the drones location in relation to its surroundings, is used to help determine altitude and monitor for potential hazards such as trees, flock of birds, kites, powerlines etc. This is all to ensure that the drone does not pose a risk to property, pedestrians or vital workplace assets.
VLOS Distances
VLOS distances vary for a number of reasons. The larger the drone, the easier it is to see further away. A calm, clear day will allow you to see the drone for further than if it was a grey overcast afternoon. Even the drone pilots eyesight can vary the distance of VLOS. This is where pilot judgement is required to take into considerations the unique surroundings at the time.
