If you fly in the UK countryside, you will at some point cross into a conservation area. There are seven major designations, none of which name themselves clearly, all of which sound similar, and only some of which legally restrict drone operation. Here's the actual hierarchy.
Sites of Special Scientific Interest (SSSI)
The bedrock of UK conservation. Designated under the Wildlife and Countryside Act 1981 by Natural England, NatureScot, NRW, and DAERA across the four nations. There are over 6,500 SSSIs across the UK covering ~8% of land area.
Drone impact: It is a criminal offence to disturb the protected features of a SSSI, but overflight in itself is not automatically a disturbance. Low-altitude flight that flushes nesting birds, disturbs grazing deer, or causes seal pupping interruption can be prosecuted. Practical rule: stay above 100 ft AGL when overflying SSSIs during sensitive seasons (March–August for ground-nesting birds).
Special Areas of Conservation (SAC)
EU Habitats Directive designation, retained in UK law post-Brexit. Targets habitats rather than species — chalk grassland, blanket bog, salt marsh. Often overlap with SSSIs.
Drone impact: Similar to SSSI — overflight is not banned, but disturbance prosecutions are possible if the activity damages the protected habitat (e.g., low-altitude landing on chalk grassland during ground-orchid flowering season).
Special Protection Areas (SPA)
EU Birds Directive designation. Specifically protects breeding, wintering, and migratory bird populations. The most drone-relevant designation because birds are exactly what drones disturb.
Drone impact: Take this one seriously. Wildfowl and waders are easily flushed, and repeated disturbance can cause breeding failure. Several SPAs have explicit drone-flight restrictions in their byelaws (e.g., The Wash, Morecambe Bay, Solway Firth).
Ramsar Sites
International convention for wetlands of global importance. UK has 175 Ramsar sites. Often overlap with SPAs and SSSIs. Same drone considerations as SPAs — flushing wading birds is the main concern.
National Nature Reserves (NNR)
Selected SSSIs that are also actively managed for public access and education. Run by Natural England, NatureScot, NRW, and DAERA. Many NNRs have explicit drone byelaws — often a complete prohibition without ranger permission.
Areas of Outstanding Natural Beauty (AONB / National Landscape)
Renamed "National Landscapes" in November 2023. Landscape-scale designation focused on visual amenity. No automatic drone flight restriction from the AONB designation alone. Local byelaws (e.g., Surrey Hills, Cotswolds) sometimes apply on specific landholdings.
National Parks (England, Wales, Scotland)
The UK has 15 National Parks. Each has its own byelaws. Lake District, Snowdonia, and the Peak District all have site-specific drone restrictions on certain landholdings. The whole park is not blanket-banned, but specific car parks, viewpoints, and visitor centres frequently are.
The cumulative rule
Conservation designations stack. A coastal site can simultaneously be a SSSI, SAC, SPA, Ramsar, and inside an AONB. Disturbance liability stacks with it. If in doubt: stay above 100 ft AGL, avoid take-off and landing on the protected ground, and never approach concentrations of birds or mammals.
The legal teeth
The strongest enforcement is through Section 28P of the Wildlife and Countryside Act 1981 for SSSI damage (up to £20,000 fine on summary conviction; unlimited on indictment) and the Conservation of Habitats and Species Regulations 2017 for SAC and SPA disturbance (criminal offence, fines).
Realistically, prosecutions for drone overflight specifically are rare. Prosecutions for disturbance caused by drones — flushing nesting birds, causing seal pupping disruption, scaring deer over a cliff — happen regularly. The pattern is consistent: if your flight visibly affected wildlife, you have a problem. If it didn't, you typically don't.