Checking aerodrome safeguarding before designing tall structures

An aerodrome safeguarding map will tell you the maximum height you can build on a site before any planning policy does, and the map is sitting in your local planning authority's filing system. Ask for it at the point you take an interest in the land. On a site within an approach zone it can cap a scheme at a height no amount of design quality will overcome.

Safeguarding also catches things nobody expects. A balancing pond. A reedbed. A green roof. A crane. Solar panels on a warehouse roof. Each of those has stopped or reshaped schemes at the consultation stage, and each is cheaper to design around than to argue about.

Which aerodromes are officially safeguarded

Official safeguarding operates through a government direction requiring local planning authorities to consult on specified development within defined areas. Three categories are covered: aerodromes, technical sites such as radar installations and navigation aids, and military explosives storage areas.

The operator prepares safeguarding maps, which are deposited with the authority. The authority then has a duty to consult the operator on applications meeting the triggers shown. That duty is procedural: the operator's objection is a material consideration rather than a veto, but a holding objection from an aerodrome is very difficult to overcome.

Not every airfield is officially safeguarded. Smaller aerodromes may operate unofficial safeguarding arrangements, and some authorities consult them voluntarily. Where that is the case, the operator's views still carry weight, so identify airfields within range whether or not a map exists.

Military aerodromes and defence technical sites bring a separate consultee, and the safeguarding areas around explosives storage sites work differently again, constraining population density rather than height.

Reading a safeguarding map and its height contours

Request the maps in writing and ask for them at a usable scale, with a note of the datum used.

Safeguarding maps show a series of zones drawn from the runway geometry. They follow the obstacle limitation surfaces defined in the aviation licensing standards. Approach and take-off climb surfaces rise away from the runway ends. Transitional surfaces rise from the runway strip edges. An inner horizontal surface sits at a fixed height above aerodrome level, with a conical surface beyond it.

Two conversions cause most errors. Heights on the map are normally expressed against a datum such as aerodrome elevation or ordnance datum, while your architect is thinking in metres above finished floor level. And existing ground level has to come from a topographic survey rather than from spot heights on a mapping product, because a metre of error at ground level is a metre of error at roof level.

Work out three figures early: existing ground level at the highest point of the footprint, the proposed height of the tallest part including plant, lift overruns, parapets and lightning protection, and the safeguarding contour at that location. Then state all three in the application.

Consultation triggers by height and distance

The triggers come from the direction and from the deposited map, and they are aerodrome specific because the contours follow the runway.

Do not apply a remembered figure. Check the map, confirm the position with the authority, and record the date you checked. Where a scheme sits close to a threshold, ask the operator directly rather than relying on the map, because the operator holds the current surfaces.

Comparable decisions in the same area are informative too, and searching decision data across authorities will show how the operator has responded to similar heights nearby.

Birdstrike safeguarding and what attracts it

This is the trigger that catches schemes with no tall element at all.

Birdstrike safeguarding covers development likely to increase bird numbers or to change bird movements within a consultation zone around the aerodrome, commonly extending to 13 kilometres. The list of relevant development is broad: landfill and waste transfer, sewage treatment, reservoirs, attenuation basins and open water features, wetland and reedbed creation, nature reserves, large areas of amenity grassland, green and brown roofs, food waste handling, and some agricultural changes.

The tension with other policy requirements is real and it is not resolved anywhere. Drainage policy pushes towards open water. Biodiversity net gain pushes towards wetland habitat, which scores well on the statutory metric. Safeguarding pushes the other way.

Resolve it in the design rather than in the argument. Dry attenuation basins that hold water only in extreme events. Sub-surface storage. Habitat creation focused on species-rich grassland, scrub and woodland rather than open water. Planting regimes and management plans that discourage flocking species. Where open water cannot be avoided, a bird hazard management plan agreed with the operator is the usual route.

As an illustrative example, a 4 hectare logistics scheme 9 kilometres from a busy airport, with a large open attenuation basin and a wildflower and wetland biodiversity strategy, will attract a safeguarding objection. The same scheme with cellular storage under the yard, a dry swale system and grassland and scrub habitat will not.

Cranes and temporary structures

A tower crane stands well above the building it is putting up, so a scheme that clears the safeguarding contour on completion can breach it for eighteen months.

Deal with it during the application. Identify the likely crane type and maximum height, notify the aerodrome operator, and expect to agree an operating plan covering maximum jib height, slewing arrangements, out of hours positioning and obstacle lighting. Where the crane penetrates a surface, temporary procedures may be needed on the aerodrome side, which takes lead time.

Piling rigs, scaffolding, temporary masts and even a telehandler on a raised platform can matter on constrained sites. List everything above the finished parapet in the construction method statement, not just the crane.

Technical safeguarding for radar and navigation aids

Structures interfere with aviation systems in ways that are not intuitive from their height alone.

A building can reflect radar signals and produce clutter or false returns. It can shadow a radar, creating a gap in coverage. It can degrade an instrument landing system or a navigation aid. Metal cladding, curved facades and large flat surfaces all affect this, so the assessment depends on form and material rather than only on dimensions.

Reflected light is the other technical issue. Glint and glare from glazed elevations, metal roofs and solar photovoltaic arrays is assessed towards control towers and along approach paths, and operators object where the geometry is unfavourable. A glint and glare assessment needs the array layout and the facade specification to be reasonably settled, which is a reason not to leave it to the end.

Obstacle lighting runs against most local lighting policy, so where aviation lighting is required, the Lighting Assessment has to reconcile it with obtrusive light limits and any dark skies designation. Say in the document that the aviation requirement takes precedence and explain how spill has been minimised.

Engaging the operator early

One email, sent before the design is fixed, saves months.

Send the aerodrome safeguarding team the site coordinates, a location plan, the proposed maximum height with the datum stated, the footprint, and a description of any water features, habitat creation or reflective surfaces. Ask for a written position and an indication of what would change it.

Then keep the correspondence. Where an operator confirms no objection to a stated height, that letter is the document that stops the point being reopened at committee. Where an operator raises a concern, you have time to redesign rather than to negotiate under a determination deadline.

Three further habits. Check whether the air navigation service provider needs consulting separately. Check the Ministry of Defence position where a military aerodrome or technical site is within range. And make sure the height stated in the application, the height on the drawings and the height in the Townscape and Visual Impact Assessment are the same number, because a discrepancy invites the operator to assume the worst.

Aerodrome safeguarding sits alongside the other early screening exercises that shape a layout before the architect starts, and checking strategic noise maps before layout belongs in the same first week of work.

Enter your postcode on PlanScope to see which reports a tall or large scheme on your site is likely to need.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.