Modified Access Pricing (MAP) is a pricing mechanism used in the aviation industry to allocate airport slots and capacity to airlines. It's a modified version of the traditional first-come, first-served (FCFS) system, which can lead to inefficiencies and congestion at busy airports.

In a traditional FCFS system, airlines are allocated slots based on the order in which they request them. However, this can result in:

1. Inefficient use of airport capacity: Airlines may not always use their allocated slots efficiently, leading to wasted capacity and congestion.
2. Inequitable distribution of slots: Airlines with more resources and better connections may be able to secure more slots, while smaller airlines may struggle to get a fair share.

Modified Access Pricing addresses these issues by introducing a pricing mechanism that rewards airlines for using their allocated slots efficiently. Here's how it works:

1. Airlines are allocated slots based on their historical usage and efficiency.
2. Airlines are charged a fee for each slot they use, with the fee increasing for each additional slot they use.
3. Airlines are incentivized to use their allocated slots efficiently, as they'll be charged more for using additional slots.

The goal of MAP is to:

1. Encourage airlines to use their allocated slots efficiently, reducing congestion and increasing airport capacity.
2. Promote a more equitable distribution of slots, giving smaller airlines a better chance to secure slots and compete with larger airlines.
3. Generate revenue for airports, which can be used to invest in infrastructure and improve the overall passenger experience.

In summary, Modified Access Pricing is a pricing mechanism that aims to optimize the use of airport capacity, promote efficiency, and encourage a more equitable distribution of slots among airlines. It's an innovative approach to managing airport congestion and capacity, and it's being implemented at several airports around the world.