Foster and Partners, Richard Rogers, Grimshaw and Reid Architecture have all been asked to submit designs for the vast project.
The airport authority has also drawn up a list of structural engineers to work on the scheme. They are: Arup, Buro Happold, Halcrow, Whitbybird and
While all will surely be unable to resist submitting designs, there will be concern among some that the scheme could risk mirroring Terminal 5, which suffered a planning process of nearly 15 years.
Mike Forster, BAA business strategy director, said: 'The Heathrow East Terminal proposal is at a very early stage. We are currently in active discussion with airlines and other stakeholders, assessing the viability of the project.
'As these discussions take place we need to prepare for the commencement of early design and development work and this is why we have approached the above organisations.
'This early work is critical as it will help us understand the key elements of the potential project,' Forster added.
BAA has also drawn up a list of four building services companies to look at the scheme. They are Amec, Arup, Hoare Lea and WSP.