Often, low-cost carriers fly to smaller, less congested secondary airports and/or fly to airports during off-peak hours to avoid air traffic delays and take advantage of lower landing fees. This is why Ryanair flies to Gatwick Airport, Luton Airport, and Stansted Airport in the London area and how easyJet is able to fly to Paris-Charles de Gaulle, and Amsterdam. In London's case however, low-cost carriers would not be able to use Heathrow anyway as the airport is running at near capacity, so there is no room to build a base. The airlines tend to offload, service and re-load the aircraft (turnaround) in shorter time periods and don't wait for late passengers, allowing maximum utilization of aircraft.