An increasing number of European airports have become capacity constrained due either to physical limitations on runway provision (e.g. Paris CDG, Munich, Barcelona) or environmental limitations on aircraft movements (e.g. Amsterdam Schiphol, Dusseldorf, Milan Linate). This paper draws upon the history of capacity limits in the London airport system which have been reached for many years at Heathrow and Gatwick as well as slot controlled airports in the US such as Washington Reagan National and New York La Guardia.
Congested airports and network carriers have developed strategies to make the best use of scarce capacity. This paper aims to review these and analyse the impact on air service provision.
Government policy is the first area considered. Heathrow and Gatwick charges are regulated by the CAA while in other respects airports compete under private ownership. A combination of market forces and grandfather rights has shaped the current airline networks. Slot trading has led to operations migrating to those airlines who value them most.
Commercial reactions to scarce capacity are evaluated. Aircraft size is shown to have increased in most cases although British Airways (BA) has replaced B757s at Heathrow with smaller A319s/A320s. The consequences of bmi British Midland being absorbed by BA are quantified in routes, frequencies and capacity operated. Minor routes are seen to be squeezed out while rival alliances have chosen to divert traffic through their hubs elsewhere. Gatwick has priced out small aircraft with fixed landing fees (not weight based) and a minimum number of passengers that must be paid for. This led to flybe exiting the airport and selling its slots to easyjet.
Thin routes are shown to be the most vulnerable with services such as Strasbourg, Bremen and Antwerp relocated to other London airports using larger aircraft but at reduced frequency. This has particular implications for business travel convenience and connections to long-haul flights. Secondary and regional airports have captured much of the growth, driven by LCCs operating on short-haul routes and passengers increasingly use their local airport for such journeys. It is noted however that the market at the major airports is more resilient in times of high fuel prices, economic recession or the current pandemic.
In the US, airlines have increased market concentration through slot swaps and substituted larger aircraft and busier destinations for thin local routes. These were inefficient users of scarce capacity but often important links for the communities concerned.
Congestion has increased journey times of flights at the major airports with negative cost and environmental implications, while secondary and regional airports are much more dependent on the private car as a means of surface access which brings different problems.
The implications of the reduction in demand during the covid-19 pandemic for use of slots at busy airports are considered and some of these are thought to be transitory although down gauging of aircraft fleets with retirement of the B747, A380 etc and the slower revival of long-haul travel are expected to have ongoing effects.
Conclusions are drawn which will have wider applicability for other airports and cities running into limits on number of flights.