The government decision on the third runway is expected to be announced before Christmas. According to the Evening Standard, BAA fears environmental and financial concerns might see ministers back away from expansion and opt for allowing more flights from the existing runways.
The Conservatives have already come out against a third runway. Instead, they support a high-speed rail link so Heathrow passengers can easily reach other parts of the country.
BAA says that improving rail services without adding a new runway would prove a "false and dangerous" decision which would leave Britain at a severe disadvantage.
BAA urged the rail industry to work with the aviation sector to generate a "once-in-a- generation opportunity to create a world-leading air and transport hub at Heathrow". BAA said its aim is for a "third runway built within strict environmental limits and a high-speed rail network that will connect the UK's hub airport with every major centre of population across the country".
Stuart Condie, BAA's director of planning and surface access, said: "Our vision is simple; it is one where, in the next decade, a three-runway Heathrow airport strengthens the UK's connections with global markets, particularly those in China and India."
Separately, it has been reported that Construction Director Andrew Wolstenholme, the man responsible for the on-time construction of T5, is to move to become Managing Director of a division of Balfour Beatty.