Ministry of Defence safeguarding and consultation zones

A Ministry of Defence safeguarding zone around an aerodrome, a technical site or an explosives storage area means the local planning authority must consult the MoD before deciding certain applications, and the consultation is not a formality. The ministry of defence safeguarding zone planning regime works through directions and safeguarding maps supplied to councils, and an objection from the Defence Infrastructure Organisation carries the weight of a statutory consultee response.

It is also quiet. Most applicants find out they are inside a zone when the case officer forwards an objection in week six.

The categories and what each protects

Defence safeguarding is not one thing. The zones protect different operational interests and ask different questions of a proposal.

Aerodrome safeguarding protects military airfields from obstruction and from hazards to flight. Its concerns are the height of structures on approach and climb-out surfaces, lighting that could be confused with runway lighting or that dazzles crews, reflective materials, and anything that attracts birds in numbers, such as open water, landfill or extensive flat roofs with standing water.

Technical site safeguarding protects radar, navigation aids, communications and meteorological installations from physical obstruction and from electromagnetic interference. A building, a wind turbine, a solar array or even a run of metal cladding can degrade a radar picture.

Explosives safeguarding protects people from the consequences of an incident at a military explosives storage area. The zones work outwards from the storage in bands, and the question asked of a proposal is about the number of people it would introduce and how they would be housed, rather than about its height or appearance.

Then there is the wider interest in training areas, danger areas and low flying, which is handled through consultation rather than through mapped safeguarding.

Checking whether a site falls in a zone

Safeguarding maps are issued to local planning authorities, so the council holds the definitive answer for its area. Ask the duty planning officer, or search the council's constraints layer where it publishes one.

Three practical checks before you commission anything:

1. Ask the council to confirm in writing which safeguarding zones, if any, affect the site, and which consultee they will notify.
2. Look at the national designation datasets on planning.data.gov.uk for the mapped constraints the council has published.
3. Where the scheme involves a tall structure, a turbine or a solar array, approach the Defence Infrastructure Organisation directly before submission rather than waiting for consultation.

Pre-submission contact is the single most useful step. An objection raised informally at concept stage can usually be designed out. The same objection at week six costs a redesign and an extension of time.

Height, turbines and radar

For tall buildings, cranes and masts near a military aerodrome, the question is geometric. Does the structure penetrate a safeguarded surface, and does it do so by an amount the ministry can accept with lighting or without.

Wind turbines are the most contested category. A turbine is tall, it moves, and the rotating blades return a signal that can clutter a primary radar display. Objections are rarely about a single turbine's visual effect and usually about the radar picture, which is why they are hard to negotiate away with landscaping.

Where radar is the issue, the possible resolutions are technical: relocating within the site, reducing tip height, blanking a radar sector, or in some cases a mitigation scheme agreed with the ministry and secured by condition or obligation. All of them need the ministry's engagement, and none of them is quick.

Solar development raises glint and glare near aerodromes. An assessment of reflected light on approach paths and on the control tower is the standard evidence, prepared by someone who models it properly.

Cranes are worth a separate thought. A building that sits comfortably below a safeguarded surface may need a tower crane that does not, and the ministry will ask about the crane before it comments on the building. Agree an operating envelope and a notification procedure for the construction period and put it in the submission, because discovering it after permission means a separate application or a condition you cannot comply with on programme.

Explosives safeguarding and how many people a scheme brings

Inside an explosives safeguarding area the test turns on population. A single dwelling replacing another may be acceptable where 40 flats would not, and a building occupied in daytime only is treated differently from one where people sleep.

Set out plainly in your Planning Statement the number of units, the expected occupancy, the hours the building is used and the building's construction. The ministry's response will be proportionate to those figures, so getting them into the submission early saves a round of questions.

Where a scheme is refused on this basis, the planning balance is the argument rather than the facts. Councils give substantial weight to defence safeguarding, and the Planning Inspectorate has treated public safety objections from statutory consultees seriously.

Densification is the pressure point. A site inside an explosives safeguarding area that was acceptable for four houses ten years ago does not automatically take twelve flats now, and the allocation of the site in a local plan does not resolve the point either. Where the plan allocated the land without resolving the safeguarding question, the applicant inherits the problem at application stage.

How objections get framed and what resolves them

A defence objection usually names the safeguarded asset, the surface or zone engaged, the effect, and whether mitigation is possible. It will often offer a holding objection pending further information, which is the most useful outcome because it tells you what the ministry needs.

What resolves them, in rough order of frequency:

• a reduction in height or a relocation within the site
• a lighting specification controlling intensity, colour and direction
• a bird hazard management plan where open water or a green roof is proposed
• a materials condition limiting reflective finishes
• a crane operating agreement for the construction period
• a radar mitigation scheme, where the ministry will accept one

Conditions are the usual mechanism. Expect them to be precise, because a vague condition is no protection to an operational airfield. Our note on the weight local plan site allocations carry is worth reading alongside this, because an allocated site inside a safeguarding zone still has to satisfy the consultee.

Where safeguarding sits among other constraints

Defence safeguarding is separate from civil aviation safeguarding, which is operated by aerodrome licence holders and the Civil Aviation Authority for civil airports, and from the aerodrome-related provisions in the Town and Country Planning (Development Management Procedure) (England) Order 2015. A site can sit in both regimes, and the two consultees ask different questions about the same structure.

It is also separate from the lighting assessment a council's environmental health team wants for amenity reasons, though one Lighting Assessment can often serve both audiences if it is scoped to cover obtrusive light and the aerodrome's requirements.

The practical sequence for a site inside a zone: confirm the zone, talk to the ministry, design to the constraint, then submit with the safeguarding matters addressed in the planning statement rather than left for the consultation stage. Applications that do that are decided on time. Those that do not spend two months in correspondence.

Where a scheme involves a tall structure, test the geometry before the architecture. It is much easier to lose two storeys on a sketch than on a planning committee agenda.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.

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