The airline is grounding its fleet of Boeing 747s four years ahead of schedule because the pandemic has depressed demand for air travel.

“It is sadly another difficult but necessary step as we prepare for a very different future,” British Airways Chairman and CEO Alex Cruz said in a statement Friday.

The airline said it had already started phasing out the 747s and planned to retire the last of them in 2024. They eat up a lot of fuel and were 23 years old on average, British Airways said, far older than the average age of about 13 years among major US carriers.

But COVID-19 accelerated that timeline. The pandemic has devastated airlines with travel restrictions and lockdown measures, and British Airways doesn’t expect the industry to recover until 2023 or 2024.

BOAC, which later became British Airways, started flying the double-decker jet known as the “Queen of the Skies” from London to New York in 1971. British Airways added the modern 747-400 model to its fleet in 1989 and still owns 31 of them as of this year, making it the world’s largest operator of that plane.

British Airways said it plans to run more flights on “modern, fuel-efficient aircraft,” such as the Airbus A350 and Boeing’s 787, in its quest to achieve “net zero carbon emissions” by 2050. But Cruz called the decision to retire the storied 747s “heart-breaking” and said they will “always hold a special place in our hearts at British Airways.”

“So many people, including many thousands of our colleagues past and present, have spent countless hours on and with these wonderful planes — they have been at the center of so many memories, including my very first long-haul flight,” he said.