Analysis used in the Airports Commission’s final report backing a third runway at Heathrow has been criticised as “flawed” by rival Gatwick.

The airport is to write to prime minister David Cameron with its concerns covering some of the Commission’s data, analysis and findings.

This has resulted in an understatement of both Gatwick’s strengths and Heathrow’s challenges.

Gatwick claims the Commission has under-forecast future traffic at an expanded Gatwick; failed to consider the role Gatwick could play in the long haul sector; glossed over the noise impact of a third runway at Heathrow; and downplayed the “very considerable delivery risks and financial challenges” of expanding Heathrow.

Gatwick airport board chairman, Sir Roy McNulty, said: “Our view has always been that the assessments on which the commission’s conclusions are based must be thorough, balanced, fair and well evidenced.

“We believe that the Commission’s report falls short of this standard in a number of very important respects.

“As a result, the many strengths of Gatwick and the many challenges of Heathrow are underplayed, leading to a conclusion which we believe is flawed.

“The Airports Commission has made its recommendation and it is now for the government to decide.

“We are confident that when they do make their decision they will choose Gatwick as the best option for the economy and the environment, and – most importantly – after decades of delay the option that is actually deliverable.”