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Crowds in the air Graphing airfares and passenger load factors


Do you feel lucky if no one sits beside you on an airplane? Lucky might be the right word for it: According to data provided by the U.S. Bureau of Transportation Statistics (BTS), the chance of having an empty seat next to you has been getting slimmer over time.

Over the past two decades, passenger load factors in the U.S. have been rising as air travel has gotten more crowded. Roughly speaking, passenger load factor is the average percentage of airplane seats occupied across all flights. A load factor of 0 percent indicates an empty flight while a load factor of 100 percent indicates a full flight. Because each flight has different capacities and travel distances, the BTS adjusts the official load factor statistics by the size of the airplanes as well as the flight distances.

The top graph plots the load factor for U.S. domestic flights. The red line and blue line indicate the load factors before and after seasonal adjustment, respectively. The load factor increased gradually from about 70 percent in 2000 to about 85 percent in 2017. This trend implies that the airline industry has taken better advantage of the capacity of airplanes over time. In addition, the significant gaps between the lines reflect the seasonality of air travel, with summers being the most popular time to fly. However, these seasonal gaps seem to shrink over time. One possible explanation could be that the airline industry has improved its use of airplane capacity in the winter when traveling is less popular.

This 15-percentage-point increase in load factor, from 70 percent to 85 percent, likely makes a passenger’s flight feel significantly more crowded. Consider a single-aisle aircraft with three seats on each side of the aisle. If the load factor were 66 percent, which is not far from the 70 percent number in 2000, then ideally no one would have to sit in the middle seat and there would be an empty seat between each passenger. As the load factor increases from 66 percent to 85 percent, the percentage of passengers sitting next to an empty seat drops from 100 percent to 30 percent. This more-confined experience could make some passengers more willing to pay extra fees for preferred seats or seats with better legroom.

However, the higher load factors produce some benefits for consumers: The average airfare has been lower because airlines have been putting their capacity to better use. The bottom graph shows that airfares have decreased over the past several years.

How these graphs were created: For the top graph, search for “domestic load factor, scheduled passenger flights,” check the seasonally adjusted and not seasonally adjusted series, and click the “Add to Graph” button near the top of the search results. For the bottom graph, search for “consumer price index for all urban consumers: airline fare,” check the seasonally adjusted series, and click the “Add to Graph” button.

Suggested by YiLi Chien.

View on FRED, series used in this post: CUSR0000SETG01, LOADFACTORD, LOADFACTORDD11


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