Heathrow Airport has criticised Department for Transport forecasts on passenger demand and capacity needs in a submission to the Davies Commission.
The Heathrow submission says the DfT has incorrectly assumed that passengers who cannot be accommodated at Heathrow will fly from other UK airports.
The airport argues people who can’t fly from Heathrow are more likely to fly long haul via overseas hubs such as Dubai.
The Davies Commission was set up last year by the government to examine the demand for increased hub-airport capacity in the south east and suggest ways to meet it.
The Commission is due to report in full in 2015, but should publish an interim report late this year.
Heathrow has told the Commission, chaired by Sir Howard Davies, that: “DfT forecasts incorrectly assume that, with Heathrow constrained, long-haul demand and to an extent transfer demand will get picked up at other UK airports.
“In practice, network economics and the related airline business model make this highly unlikely. Instead, overseas hubs and economies are the beneficiaries.
“The issue is leading the government to underestimate the pressing nature of the hub capacity constraint and its damaging impact on UK intercontinental connectivity.”
Heathrow said the DfT must: “Take account of network or hub economics and . . . must properly account for transfer passengers.”