Tweaking routes to achieve the most efficient and profitable network is a never-ending task for airlines. Questions like whether or not to fly three-times a day between Chicago and Omaha on a Boeing 737 or six-times a day on a Bombardier CRJ200 are common.

This constant tweaking is behind many of the largest changes in domestic US capacity from September 2013 to this September. Looking at absolute changes and percentage changes in available seat miles (ASMs) two different pictures of US capacity emerge – the former dominated by larger markets where mainline carriers and those who compete with them continue to define their place in the national market and the latter by smaller markets where smaller carriers or changes in capacity make big differences.

US capacity absolute Sep13v14

Los Angeles touched four of the five routes with the largest absolute capacity increases in September. On a high level, these are attributable to the jockeying by almost every major carrier in the USA, including Alaska Airlines, American Airlines, Delta Air Lines, Southwest Airlines, United Airlines and Virgin America, for a sizeable portion of the market.

Routes to Honolulu and Boston from Los Angeles saw capacity changes among existing carriers. Increases on Hawaiian Airlines and Delta outweighed decreases on American and United on the former, and American and Delta increased capacity while other carriers remained flat on the latter compared to a year earlier, Innovata Flightmaps Analytics data shows.

Kahului and Minneapolis/St. Paul both saw new service from Los Angeles. Hawaiian launched a nonstop on the Kahului route with an Airbus A330-200 in May, and United began twice-daily service on the Minneapolis/St. Paul route in April and Spirit Airlines once daily in November 2013.

JetBlue Airways and United both increased capacity on the Boston-San Francisco route, outweighing a slight decrease by Virgin America, in September.

The largest decreases in capacity are mostly attributable to larger network changes. Delta will end its seasonal Anchorage-Salt Lake City flight in September this year, the airline confirms. This is likely due to the growth of its new hub at Seattle/Tacoma International airport where it can more efficiently flow passengers from Anchorage into the lower 48 states.

United discontinued its Los Angeles-Pittsburgh flight in August, which comes five months after its codeshare with US Airways ended following the latter’s merger with American. US Airways operated a hub in Pittsburgh until 2008 and retains a large presence in the city.

JetBlue discontinued its daily flight between Portland (Oregon) and Boston during the year as it focuses growth in the Caribbean and Latin America, and at Washington National airport. Capacity on Alaska was flat in September.

Capacity adjustments impacted the Houston Intercontinental-San Francisco and New York-Tampa routes. United decreased capacity on the former, which is between two of its largest hubs, while American discontinued its service and Delta, JetBlue Airways and United cut capacity on the latter.

US capacity percent Sep13v14

Leisure routes and smaller markets saw the largest percentage changes in capacity in September, Innovata data shows. Frequency and aircraft changes drove the increases on the five routes that saw significant jumps.

Allegiant Air added frequency on both the Chattanooga-St. Petersburg and Niagara Falls-St. Petersburg routes, and Delta increased monthly frequency on the Jackson Hole-Atlanta route, Innovata shows. Southwest operated the Nashville-Pittsburgh route for the full month this year after launching the route at the end of September 2013.

Southwest operated flights on the Columbus-Fort Myers route with a Boeing 737 all month compared to on an AirTran Airways Boeing 717-200 a year earlier. A 737-300 with Southwest’s new Evolve interior has 26 more seats than a 717.

Seasonal schedule adjustments and network changes drove most of the capacity decreases. Delta ended its seasonal Anchorage-Salt Lake City service earlier this year than in 2013, and Southwest made adjustments in its seasonal Baltimore/Washington-Panama City (Florida) schedule this September.

Southwest discontinued service on both the Branson-Houston Hobby and Branson-Chicago Midway routes in June 2014. Buzz Airways replaced them in both markets but with 30-seat BAe Jetstream 41s instead of 737s.

Delta shifted its existing Minneapolis/St. Paul-Birmingham (Alabama) flight to a 50-seat Bombardier CRJ200 from a larger aircraft between September 2013 and this September, resulting in the capacity decrease in that market.

Source: Cirium Dashboard