Temporary Danger Areas

What a Temporary Danger Area is, and why BVLOS operators use one

The CAA's policy on special use airspace (SARG Policy 133, February 2024) defines a danger area as airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times. Permanent danger areas are listed in the en-route (ENR) section of the UK Aeronautical Information Publication (AIP). A temporary one exists only for a limited period and is published instead in an AIP Supplement or an Aeronautical Information Circular (AIC).

The CAA's additional guidance for BVLOS airspace changes (CAP 2989) explains why drone operators need this. Remotely piloted aircraft flown BVLOS cannot currently operate in line with the rules of the air, so they are flown in special use airspace to reduce the risk of a mid-air collision. Because operators often fly in different places, or in one place for a short time, that airspace is usually requested through the temporary or trial airspace change process rather than made permanent.

The policy also sets design principles. The structure should be as small as practicable, with simple boundaries, and its vertical limits and activation times should be the minimum the activity needs. Outside prohibited and restricted areas, special use airspace should only be active when the activity is taking place.

A TDA covers the airspace only, and the flight needs its own permission. CAP 2989 states that the airspace change and the operator's application are separate but depend on each other, that a BVLOS airspace change needs an operational authorization to be issued as well, and that no flying is permitted until the operator has received that authorization.

How the temporary airspace change process works

CAP 1616 version 6, the CAA's airspace change process, came into effect on 1 October 2026, and new proposals submitted after that date follow it. Non-permanent proposals use CAP 1616k (first edition, September 2026), which replaces CAP 1616g for proposals covered by the Air Navigation Guidance 2026. The CAA says some earlier proposals may continue under previous versions, so confirm which applies to yours.

CAP 1616k covers two types of non-permanent change. A temporary change to airspace design lasts for a fixed period, normally no more than 180 consecutive days from first activation unless the CAA decides otherwise. An airspace trial tests or gathers evidence on a design or procedure, or supports bringing new airspace users into UK airspace, and normally lasts no more than three years. Your statement of need lets the CAA decide which type fits. Older CAA guidance, including the 2024 special use airspace policy, gives 90 consecutive days as the usual maximum for temporary structures, so check the period at your briefing meeting. Approval creates no presumption that the change will become permanent.

CAP 1616k sets out five steps:

• Step 1, initiate: submit a statement of need on form ARF 1916 and brief the CAA at a briefing and guidance meeting. The CAA then publishes a Step 2 assessment scope plan that sets the work you must complete.
• Step 2, design, assess and engage: develop the design, carry out the assessments the scope plan asks for (such as safety and policy, operational impact and planning, plus noise, protected areas and European sites where required) and engage aviation stakeholders.
• Step 3, update and submit: consider the feedback, finalise the design and submit the final proposal using the CAA's template, publishing it on the airspace change portal.
• Step 4, CAA decision: the CAA normally aims to decide within 28 days of receiving a completed proposal and may attach conditions or modifications.
• Step 5, implement: meet any conditions, publish the aeronautical information and tell airspace users about the change.

Sponsor duties, engagement and publication

The sponsor is the organization that originates and progresses the airspace change. CAP 2989 describes the sponsor and the drone operator as separate roles: one organization can hold both, or two can share them. Where they differ, CAP 1616k says the sponsor must make sure the parallel activities, such as a UK SORA-based application for an operational authorization, are coordinated and that any dependencies are managed. The CAA can take evidence from those activities into account to avoid duplicated work.

Where the scope plan requires engagement, the sponsor must identify aviation stakeholders likely to be affected and engage them to test whether the proposal is safe and operationally viable. CAP 1616k gives examples such as local airspace users, air navigation service providers, aerodromes, Defense Airspace and Air Traffic Management (DAATM) and members of the National Air Traffic Management Advisory Committee (NATMAC). It does not set a fixed length. The period must be proportionate to the scale and impacts of the change, and the final submission must give the start and end dates, the reason for that length and records of the engagement. Under the earlier CAP 1616G process, CAP 2989 set a minimum of four weeks for BVLOS proposals.

Procedures for running a danger area should sit in a letter of agreement between the activity sponsor, the relevant air traffic control units and other stakeholders. CAP 2989 adds that temporary operating instructions may also be needed where air navigation service providers or aerodromes are involved.

The CAA publishes no fixed lead time for a TDA. CAP 1616k says the length of the process depends on the proposal's complexity and the sponsor's own work, and that sponsors should allow time for implementation, safety assurance and airspace notification. After approval, the aeronautical information is normally a NOTAM, an AIC, an AIP Supplement or a combination. If the sponsor is not an air navigation service provider or a licensed or certificated aerodrome, the CAA submits the change request to the UK Aeronautical Information Service on the sponsor's behalf.

Where special use airspace is activated by NOTAM, the policy says the NOTAM should be published at least 24 hours before the activity starts, or at least 7 days ahead over the high seas, unless the CAA agrees otherwise. To extend an approved change, apply before the approval expires. The CAA normally needs at least 28 days to assess an extension request.

Alternatives the CAA is developing

An atypical air environment (AAE) is airspace the CAA agrees is rarely or never used by other aviation. It is not a separate class of airspace, and operators propose one as part of their operational authorization application. Typical examples are within 30 m (100 ft) of a building or structure, within 15 m (50 ft) of a permanent above-ground linear structure such as a railway, road or power line, and up to 15 m (50 ft) high inside private property boundaries. Example conditions include filing a NOTAM, coordinating with local airspace users, carrying ADS-B on 978 MHz (UAT), fitting high-intensity anti-collision lighting and using a containment solution.

For wider BVLOS operations, the CAA's policy concept CAP 2533 uses Temporary Reserved Areas (TRAs) together with procedures and technology to integrate BVLOS flights with other airspace users. A TRA keeps the classification of the airspace it sits in and is managed by an air navigation service provider under an agreed ruleset while active. Setting up a danger area, Temporary Segregated Area or TRA still needs an airspace change under CAP 1616. The CAA considers electronic conspicuity very likely to be an essential enabler for detect and avoid, and so likely to be essential inside BVLOS TRAs.

The CAA's Future of Flight BVLOS Roadmap (CAP 3182, October 2025) treats segregated airspace as an interim step towards integration. It aims to enable routine BVLOS operations for key government priority uses, delivered in stages up to 2027, and plans less reliance on temporary airspace structures as detect and avoid and other technology mature. The CAA says these dates depend on technical progress, industry progress and legislative change, and that it will update the document each year, so check the current version before you plan.

What a consultant does, and what to ask before hiring

A consultant can help you decide whether a TDA is the right option, scope the airspace volume, draft the statement of need, run stakeholder engagement, prepare the final proposal and keep it consistent with your operational authorization application. They cannot approve an airspace change or promise an outcome: the CAA decides. Operators can compare vetted consultants on DOC, where regulator experience is shown as verified only where it has been evidenced.

• How many temporary or trial airspace change proposals have you worked on, and under which version of CAP 1616?
• Who will act as sponsor, and who will own each document?
• How will you keep the airspace change proposal, our operations manual and any letters of agreement consistent?
• Which stakeholders do you expect us to engage for this location, and for how long?
• Have you checked whether an atypical air environment would meet our needs without new airspace?

Common mistakes

Several problems can be avoided by planning the airspace and the authorization together from the start:

• Treating the TDA as permission to fly and leaving the operational authorization until late
• Letting the airspace change proposal, operations manual and letters of agreement drift apart when the sponsor and operator are different organizations
• Asking for more airspace, height or activation time than the operation needs
• Giving stakeholders too little time to respond, or not recording the engagement dates and the reason for them
• Planning around the 28-day decision aim without allowing for further questions and publication deadlines
• Assuming the older CAP 1616G steps still apply to a new proposal