Virgin Atlantic’s US partner Delta Air Lines lifted 2015 pre-tax profits by 29% to $5.9 billion with lower fuel costs expected to boost this year’s performance.

The year-on-year rise came as the airline revealed a 42% hike in fourth quarter profits to $1.45 billion.

This came despite a 2% or $145 million drop in operating revenue for the three months, blamed on “foreign currency pressures”.

Chief executive, Richard Anderson, said: “Our 2015 performance was a record for Delta on all fronts – with industry-leading operational performance, superior customer satisfaction, and a $5.9 billion adjusted pre-tax profit.

“These results show the commitment of the Delta people to running the best airline in the world every day.

It’s an honour to reward their performance with $1.5 billion in profit sharing for the year.

He added: “As we look ahead to 2016, we have a significant opportunity to improve our performance even further.

“With over $3 billion in potential savings from lower fuel prices and numerous commercial, operational and cost initiatives already in place, we expect to again perform in the top tier of the S&P Industrials on earnings growth, margins, and cash flows this year despite global economic challenges.”

The airline’s president, Ed Bastian, said: “The success of our network actions and commercial initiatives in 2015 allowed us to grow our top line and our unit revenue premium to the industry, while overcoming nearly $700 million of revenue pressure from foreign currency.

“Looking ahead, the overall demand environment remains solid. The breadth of our network scale allows us to focus our commercial efforts on those areas of the business with the best opportunity such as the domestic marketplace, while reducing our exposure in some weaker international regions.

“While we expect international volatility and currency pressures to result in unit revenue declines of 2.5% – 4.5% for the March quarter, we should see over 10 points of margin improvement given our capacity discipline in the face of a more than 50% decline in fuel prices.”

Chief financial officer, Paul Jacobson, said: “Rigorous cost discipline is a key part of the Delta culture, which was proven by our ability to keep non-fuel unit costs flat in 2015 while significantly investing in our people, products and service.

“The first half of 2016 will see the most pressure to non-fuel unit costs, and we expect performance will improve through the year as we lap last year’s employee wage increases.”