Airport take-off and landing slots are currently allocated to airlines on an arbitrary basis, even at the most congested airports such as Heathrow and Gatwick. The right to land or take off an aeroplane at congested airports is hugely valuable - perhaps worth billions of pounds to a major airline with established rights at an international airport. However, the ownership of such rights is unclear. For the most part, airlines are allowed to use the most valuable slots simply because they have used them in the past.
Authors Keith Boyfield, David Starkie, Tom Bass and Barry Humphreys in A Market in Airport Slots recognise that there are practical and political obstacles to meaningful reform. However, they argue that reform is essential. The current system impedes new entry into the air transport market, it prevents take-off and landing slots being used by airlines that value the