AAI refers to the minimum time gap required between two aircraft that are arriving at an airport. This interval is critical to ensure safe separation between aircraft, allowing them to land safely without any risk of collisions or wake turbulence.

The AAI is usually calculated based on various factors, including:

1. Aircraft type and performance characteristics
2. Air traffic control procedures and separation standards
3. Weather conditions, such as wind, visibility, and turbulence
4. Airport layout and runway configuration
5. Air traffic volume and demand

The typical AAI values range from 2 to 5 minutes, depending on the airport and the specific arrival procedure. For example:

• For a small, general aviation airport, the AAI might be 2-3 minutes.
• For a busy commercial airport, the AAI might be 3-5 minutes.
• For a specialized airport, such as a military base or a helicopter landing area, the AAI might be shorter or longer, depending on the specific requirements.

Air traffic controllers use AAI to manage the flow of arriving aircraft, ensuring that each plane has a safe and adequate interval to land without interfering with other aircraft.