Tory MP for North Essex Bernard Jenkin is heading the group, which is likely to be announced in the next few weeks. Labour MP and former minister for London Nick Raynsford is said to be one of the first members.
The proposal was considered but rejected in the government's 2003 air transport white paper. However, London mayor Boris Johnson revived the idea in September, proposing it as an alternative to expansion at Heathrow (Planning, 26 September, p6).
Johnson confirmed this week that Crossrail chairman Douglas Oakervee will lead the Greater London Authority's preliminary feasibility study on the scheme and will advise the mayor on whether to proceed to a full-scale appraisal.
The mayor's transport director Kulveer Ranger said: "Oakervee's conclusion will be based on detailed analysis and it will be crucial in aiding a final decision on the feasibility of an airport in the Thames Estuary." The result is due early next year.