Drone Visual Line of Sight (VLOS) Rules in the UK

What Visual Line of Sight Means

Visual Line of Sight (VLOS) is a fundamental requirement for all drone operations in the UK Open category. Under the Air Navigation Order 2016 and retained EU regulation, the remote pilot must maintain continuous visual contact with the unmanned aircraft, without the aid of devices such as binoculars, monitors, or FPV goggles (unless a competent observer also maintains VLOS).

VLOS means you can see the drone clearly enough to:

• Monitor its flight path relative to other aircraft, people, vehicles, and structures
• Determine its orientation (which direction it is facing)
• Maintain separation from obstacles and hazards
• Take immediate corrective action if needed

Corrective lenses such as glasses or contact lenses are permitted. However, you cannot rely on binoculars, telescopes, or the drone's camera feed as your primary means of maintaining visual contact.

Practical Distance Limits

UK regulations do not specify a fixed maximum horizontal distance for VLOS. Instead, the limit is determined by the point at which you can no longer see your drone well enough to meet the requirements above. In practice, this distance depends on several factors:

• Drone size: A larger aircraft is visible at greater distances than a sub-250g micro drone
• Lighting conditions: Bright sunlight, overcast skies, and time of day all affect visibility
• Background contrast: A dark drone against a bright sky is easier to see than one against a dark tree line
• Pilot eyesight: Individual visual acuity varies

As a general guideline, most pilots can maintain VLOS of a medium-sized consumer drone (such as those in the 500g to 2kg range) at distances up to approximately 500 metres in good conditions. For smaller drones, this distance may be significantly less.

Weather and Environmental Factors

Weather conditions directly affect your ability to maintain VLOS. You should not fly if conditions reduce visibility to the point where you cannot reliably track your drone. Key considerations include:

• Fog, mist, or low cloud: These can obscure the drone at much shorter distances than usual
• Rain: Heavy rain reduces visibility and may also affect the drone's sensors and electronics
• Glare: Direct sunlight can make it difficult to see a drone, particularly when it is between you and the sun
• Wind: While not directly a visibility issue, strong wind can carry the drone further away faster than expected

The Role of Observers

A competent observer can assist the remote pilot by maintaining VLOS of the drone while the pilot uses a monitor or FPV goggles. The observer must be positioned so they can see the drone at all times and must have a reliable means of communicating with the pilot immediately. The observer does not need a formal qualification, but they must understand the requirements of the role and be briefed by the pilot before the flight.

Using an observer does not extend the maximum VLOS distance. The observer must still be able to see the drone clearly enough to monitor its flight path and identify hazards.

Beyond Visual Line of Sight (BVLOS)

If your operation requires flying beyond VLOS, you must apply for an Operational Authorisation from the CAA under the Specific category. BVLOS operations require a detailed risk assessment (typically using SORA), additional technical capabilities such as detect-and-avoid systems, and a higher level of pilot competence.

BVLOS authorisations are assessed on a case-by-case basis. The CAA will evaluate your ConOps, risk mitigations, equipment, and operational procedures before granting approval.