Drone Height Restrictions on Construction Sites UK 2026

The 120-Metre Rule and How It Applies on Site

The Civil Aviation Authority (CAA) sets a blanket maximum altitude of 120 metres above ground level for all unmanned aircraft operating in the Open Category. This rule, detailed in CAP 722, applies regardless of whether you are flying on a construction site, over open farmland, or in an urban area.

On construction sites, the 120-metre ceiling is measured from the surface where the drone takes off, not from the top of any building under construction. If you are standing at ground level beside a 90-metre tower block, your drone may legally reach 120 metres above the ground, placing it only 30 metres above the roof of the structure.

For inspections that require the drone to fly above the highest point of a structure taller than 120 metres, you will need to move beyond the Open Category and obtain an Operational Authorisation (OA) from the CAA under the Specific Category.

Open Category Subcategories on Construction Sites

The Open Category is divided into three subcategories, each with different proximity and weight rules. On a construction site, the most relevant distinctions are:

• A1: Flight over uninvolved people is permitted only with sub-250g drones bearing a class mark (C0). Construction workers are considered uninvolved persons unless they have given informed consent and fall under your operational control.
• A2: Drones with a C2 class mark may fly within 30 metres of uninvolved people (reducible to 5 metres in low-speed mode). This subcategory requires an A2 Certificate of Competency (A2 CofC).
• A3: Flight must remain well clear of any uninvolved persons, making this subcategory the most restrictive but also the easiest to comply with on cordoned-off sites.

If your construction site is fully fenced and only authorised personnel are present, those personnel can be briefed and considered part of the operation. This may allow you to operate under A1 or A2 conditions more readily, though a written risk assessment is strongly recommended.

When You Need a Specific Category Authorisation

Several construction scenarios push drone operations beyond the Open Category limits:

• Inspecting structures that exceed 120 metres in height, such as high-rise buildings, wind turbines, or transmission towers.
• Flying within congested areas where the site borders a densely populated zone and you cannot maintain the required separation distances.
• Operating drones weighing more than 25 kg, which are excluded from the Open Category entirely.
• Night-time operations where visibility conditions fall below the Visual Line of Sight (VLOS) requirements.

To obtain an OA, you must submit a safety case or use a Predefined Risk Assessment (PDRA) recognised by the CAA. The PDRA-S01 (VLOS over a controlled ground area) is commonly used for construction inspections. Processing times vary, so apply well before your planned flight dates.

Temporary Danger Areas and NOTAMs

Large construction projects, particularly those involving cranes or located near aerodromes, may trigger Temporary Danger Areas (TDAs) or Notices to Airmen (NOTAMs). Before flying on any construction site, check the current NOTAMs via the National Air Traffic Services (NATS) Drone Assist app or the NATS AIS website.

If the construction site sits within a Flight Restriction Zone (FRZ) — the protected airspace surrounding airports and aerodromes — you must obtain explicit permission from the relevant air traffic control unit before launching. FRZs typically extend to a radius of 2.5 nautical miles from the aerodrome reference point, with a ceiling of 2,000 feet.

Practical Height Management on Site

Modern commercial drones include built-in altitude limiters, typically set to 120 metres by default. For construction work, consider these practical steps:

• Set a conservative altitude cap: If the tallest crane on site reaches 80 metres, set your drone's altitude limit to 75 metres unless you specifically need to inspect above that height.
• Use Return-to-Home altitude wisely: Programme the Return-to-Home (RTH) altitude above the tallest obstacle on site to avoid collisions during an automatic return.
• Account for wind: Higher altitudes expose your drone to stronger winds. Construction sites with tall structures create unpredictable wind shear and turbulence around building edges.
• Log every flight: Record take-off location, maximum altitude reached, and flight duration. This data supports your operational records and any future CAA audits.

Registration and Insurance Requirements

All commercial drone operators on construction sites must hold a valid Operator ID (£10.33 per year) and each remote pilot must have a Flyer ID (free, obtained by passing a 20-question online test). Both are issued through the CAA's registration service.

Third-party liability insurance is not legally mandated for all drone flights in the UK, but virtually all construction clients and principal contractors require proof of drone insurance as a condition of site access. The minimum cover typically requested is £1 million, though many Tier 1 contractors specify £5 million or £10 million.

Beyond insurance, you should ensure your operations manual, risk assessments, and emergency procedures are documented and available for inspection. The CAA may request these at any time, and construction site managers increasingly demand them as part of their health and safety compliance frameworks.