section_path: Operations/Regulation
section_name: Regulation
paragraph_text: Regulation
  
  Until it was required to sell Gatwick and Stansted Airports, Heathrow Airport Holdings, owned mostly by FGP and Qatar Investment Authority and CDPQ held a dominant position in the London aviation market and has been heavily regulated by the Civil Aviation Authority (CAA) as to how much it can charge airlines to land. The annual increase in landing charge per passenger was capped at inflation minus 3% until 1 April 2003. From 2003 to 2007 charges increased by inflation plus 6.5% per year, taking the fee to £9.28 per passenger in 2007. In March 2008, the CAA announced that the charge would be allowed to increase by 23.5% to £12.80 from 1 April 2008 and by inflation plus 7.5% for each of the following four years. In April 2013, the CAA announced a proposal for Heathrow to charge fees calculated by inflation minus 1.3%, continuing until 2019. Whilst the charges for landing at Heathrow are determined by the CAA and Heathrow Airport Holdings, the allocation of landing slots to airlines is carried out by Airport Co-ordination Limited (ACL).
  
  Until 2008, air traffic between Heathrow and the United States was strictly governed by the countries' bilateral Bermuda II treaty. The treaty originally allowed only British Airways, Pan Am and TWA to fly from Heathrow to designated gateways in the US. In 1991, Pan Am and TWA sold their rights to United Airlines and American Airlines respectively, while Virgin Atlantic was added to the list of airlines allowed to operate on these routes. The Bermuda II Air Service Agreement was superseded by a new " open skies " agreement that was signed by the United States and the European Union on 30 April 2007 and came into effect on 30 March 2008. Shortly afterwards, additional US airlines, including Northwest Airlines, Continental Airlines, US Airways and Delta Air Lines started services to Heathrow after previously having to use Gatwick Airport. Following Brexit, the US and UK signed a new US-UK Air Transport Agreement in November 2020 incorporating the essential elements of Open Skies, which came into effect in March 2021.
  
  The airport was criticised in 2007 for overcrowding and delays; according to Heathrow Airport Holdings, Heathrow's facilities were originally designed to accommodate 55 million passengers annually. The number of passengers using the airport reached a record 70 million in 2012. In 2007 the airport was voted the world's least favourite, alongside Chicago O'Hare, in a TripAdvisor survey. However, the opening of Terminal 5 in 2008 has relieved some pressure on terminal facilities, increasing the airport's terminal capacity to 90 million passengers per year. A tie-up is also in place with McLaren Applied Technologies to optimise the general procedure, reducing delays and pollution.
  
  With only two runways operating at over 98% of their capacity, Heathrow has little room for more flights, although the use of larger aircraft such as the Airbus A380 has allowed some increase in passenger numbers. It is difficult for existing airlines to obtain landing slots to enable them to increase their services from the airport, or for new airlines to start operations. To increase the number of flights, Heathrow Airport Holdings has proposed using the existing two runways in 'mixed mode' whereby aircraft would be allowed to take off and land on the same runway. This would increase the airport's capacity from its current 480,000 movements per year to as many as 550,000 according to former British Airways CEO Willie Walsh. Heathrow Airport Holdings has also proposed building a third runway to the north of the airport, which would significantly increase traffic capacity.