 Attempts to quantify the economic impact of growth in the air transport sector generate results which depend on assumptions made , and therefore the viewpoint of the organisation making the analysis . The OEF study has produced a figure of £ 2 @.@ 5 billion per annum of additional GDP by 2015 for Heathrow , or £ 7 billion per annum by 2030 if a third runway is built there . Full implementation of the White Paper runway proposals resulted in a forecast yield of an additional £ 13 billion per annum in GDP by 2030 . Calculations done for the AEF , based on a new runway at Stansted , and which assume increased taxation of the industry , result in a negative economic benefit . 
