The Passenger Load Factor (PLF) is a key metric used in the airline industry to measure how efficiently an airline fills its seats. It is calculated by dividing the number of paying passengers by the total number of available seats, then multiplying by 100 to get a percentage. A higher PLF indicates better utilization of capacity, which can lead to increased profitability for airlines. Airlines aim for a high PLF because it reflects demand for their flights. For example, a PLF of 80% means that 80% of available seats are filled with paying passengers. This metric helps airlines make decisions about pricing, scheduling, and route planning to optimize their operations.