Few human activities are entirely risk free but, when deciding whether to authorise potentially hazardous developments, planning professionals have to keep the worst-case scenario well in mind. In a case on point, the High Court opened the way for construction of a commercial heliport despite fears that its proximity to huge fuel storage depots would present a risk of catastrophe.

The heliport was proposed for a site in the docklands area of a major city. Within a few hundred metres of the site, two companies operate depots with a joint capacity of over 100 million litres of highly inflammable distilled fuel. Both depots are sites regulated under the Control of Major Accident Hazards (COMAH) Regulations 2015. They also take on petroleum products from ships that dock at a nearby wharf, which typically contain 12-13,000 tonnes of fuel.

In challenging the local authority's decision to grant planning consent for the heliport, the companies argued that inadequate consideration had been given to the risk of a helicopter crash triggering a disaster of catastrophic proportions. The council, they asserted, had acted irrationally in abdicating responsibility for analysing the public dangers created by the proposed development.

Rejecting the companies' arguments, however, the Court found that members of the council's planning committee, and the planning officer who advised in favour of the heliport, had recognised that the risks posed to the COMAH sites were a principal issue in their consideration of the planning application.

In giving extensive consideration to that issue, the committee considered that the site's current ad hoc and ancillary use as a private helipad and hangar was less safe than a commercial heliport, which would be under the regulatory control of the Civil Aviation Authority. Use of the facility would be restricted to high-performance helicopters, flown by professional pilots. Flight paths, which would be mainly over water, would be strictly controlled.

The Court acknowledged that the planning officer erred in stating to the committee that the risk of a catastrophic helicopter failure was one in 9 billion, rather than one in 1 billion. The risk was, however, correctly recorded in the officer's written report. The report, and the debate before the committee, should not be subjected to hypercritical analysis and it was ultimately a matter of planning judgment whether the risks and mitigation measures were acceptable.