Question to the Department for Transport:

To ask the Secretary of State for Transport, pursuant to the oral statement on Airport Capacity of 25 October 2016, Official Report, column 163, on what evidential basis the figure of £61 billion was calculated for the economic benefit to the UK of expanding that airport; and what the reasons are for the difference between that figure and the £211 billion estimated by the Airports Commission.

The estimate of £61 billion includes the benefits to passengers and the wider economy of a new northwest runway at Heathrow, and was derived using established government appraisal techniques. The Airports Commission’s equivalent figure for the Heathrow Northwest runway scheme was £69 billion. The difference between the Commission’s and the DfT’s estimates reflects the DfT’s further consideration of wider economic impacts included in these figures.

Additionally, the Airports Commission used innovative modelling to estimate how airport expansion could impact on the growth in UK annual gross domestic product (GDP). The £211 billion figure represents the Commission’s estimate of the GDP impact in one of their five scenarios (“global growth”), which assumed higher global GDP growth than their central scenario. GDP and economic benefit measures are not comparable in their approach or purpose.