To ask the Secretary of State for Transport what estimate she has made of emissions of carbon dioxide resulting from stacking over London and the South East of aircraft destined for Heathrow Airport in the last year for which figures are available; and what estimate she has made of the likely amount if the proposals in the recent consultation document on possible expansion of (a) Heathrow Airport and (b) Stansted Airport are implemented. (192366)

[holding answer 7 March 2008]: Estimates of annual emissions of carbon dioxide attributable to stack-holding over London are not held centrally. No additional estimates were undertaken for the consultation on Adding Capacity at Heathrow Airport.

My right hon. Friend the Secretary of State wrote to the chief executive of NATS in September 2007 to encourage NATS to explore ways in which the performance of the air traffic control system can contribute to reducing aviation emissions.

NATS is currently consulting on the Terminal Control North airspace change proposal. This area of airspace is one of the most complex in the world, with routes in and out of major airports including Heathrow, Stansted, Luton and London City. The proposed changes are designed to reduce delay while maintaining safety and improving environmental performance. The proposal is not associated with, and does not assume, future development of Heathrow, Stansted or any other airport in the region. This consultation is a matter for NATS, and I suggest the hon. Member directs any inquiries to the chief executive.

To ask the Secretary of State for Transport what steps she is taking to minimise aircraft stacking over London; and what annual emissions of carbon dioxide she estimates arises from this practice. (188504)

[holding answer 22 February 2008]: The operation of air traffic control stacking procedures, when demand dictates or when services are affected by weather or other factors, is a matter for NATS, the air navigation services provider.

We look to NATS to operate air traffic control efficiently, including minimising stacking as far as possible, consistent with their overall objectives.

Estimates of annual emissions of carbon dioxide attributable to stack-holding over London are not held centrally.