In the context of aviation and aerospace, "Above Aerodrome Level" (AAL) is a term used to describe an altitude or height measurement that is referenced to the elevation of a specific aerodrome (airport) or airfield.

Above Aerodrome Level (AAL) is defined as the height of an aircraft or object above the elevation of the aerodrome, typically measured in feet or meters. This measurement is used to determine the altitude of an aircraft or object in relation to the aerodrome, taking into account the aerodrome's elevation above sea level.

For example, if an airport has an elevation of 500 feet above sea level, and an aircraft is flying at an altitude of 2,000 feet AAL, its actual altitude above sea level would be 2,500 feet (2,000 feet AAL + 500 feet airport elevation).

Above Aerodrome Level is an important concept in aviation and aerospace, as it helps pilots, air traffic controllers, and other aviation professionals to communicate and navigate safely. It's used in various contexts, including:

1. Altitude clearances and instructions
2. Navigation and approach procedures
3. Weather reporting and forecasting
4. Air traffic control and management

It's worth noting that AAL is different from other altitude measurements, such as:

• Above Ground Level (AGL): measures height above the ground or terrain
• Above Mean Sea Level (AMSL): measures height above the average sea level
• Flight Level (FL): measures altitude in hundreds of feet, referenced to a standard atmospheric pressure

Each of these measurements has its own specific use case and context, and understanding the differences between them is crucial for safe and efficient aviation operations.