US major, Delta Air Lines, has followed United Airlines in boosting its transcontinental offering with the introduction of an enhanced and upgraded offering on two of the busiest routes in the United States domestic market before the end of this year.

The airline has held a strong position in the market between New York and both Los Angeles International Airport and San Francisco International Airport, especially at John F Kennedy International Airport where it is the largest carrier by capacity, but has fallen behind its competitors as they have enhanced their offerings over recent years, most notably American Airlines and JetBlue with their new onboard premium service.

As of November 2015, Delta will increase service between New York-JFK and Los Angeles International Airport from nine to ten daily peak-day flights. Four flights will be operated with Boeing 767 widebody aircraft and six flights will use Boeing 757 aircraft featuring new interior modifications that have been completely refurbished from nose to tail.

Delta will also be upgrading three of its eight daily flights between New York-JFK and San Francisco to Boeing 767 widebody aircraft, making the airline the only carrier to operate widebody service on both routes. This network expansion means Delta will offer the most seats of any airline between New York JFK and Los Angeles and San Francisco this winter.

"New York JFK to Los Angeles and San Francisco are essential domestic markets from New York City, and Delta is committed to offering our customers a superior schedule and product on these routes," said Gail Grimmett, senior vice president New York, Delta Air Lines. "We're excited to expand operations at our New York JFK hub, where our nearly $2 billion investment in New York City airports has significantly benefited customers and employees over the past six years."

Delta’s growth is linked to a deal with United Airlines for the two US majors to reinforce their presence at respective New York airports. It has entered into two separate transactions with United for its US rival to acquire Delta’s slots at Newark Liberty International Airport and for it to purchase slots from United at JFK. Each transaction is subject to regulatory approval.

As part of this arrangement United revealed earlier this month that it would pull some of the Boeing 757-200s currently allocated to its transatlantic schedule and reconfigure them for its p.s. premium domestic services with flat-bed seats in the United BusinessFirst cabin and a premium in-flight service.

Our analysis of OAG Schedules Analyser data highlights the largest carriers in the Transcontinental market from New York to Los Angeles and San Francisco by available annual seat capacity. The statistics show that available One-Way seats in this market grew 47.7 per cent between 2005 and 2014, an average annual rise of 5.3 per cent. This figure will increase to over five million seats in each direction this year, based on already published schedules.