British Airways Airbus A320neo aircraft landing in a blue sky summer day at Athens International Airport AIA LGAV / ATH in Greece, on 15 July 2019. Nicolas Economou/NurPhoto via Getty Images

Airlines are carrying tons of extra fuel on flights, a practice that lets them avoid paying for fuel in countries where it’s more expensive — at the cost of the environment.

The practice was revealed by the BBC’s „Panorama“ show, which received leaked documents showing the practice at British Airways. It is believed to be widespread in the industry.

It is bad for the environment because carrying unneeded fuel makes a plane heavier and therefore causes it to emit more carbon products.

Documents showed that British Airways planes were carrying tons of extra fuel for the sake of small savings — sometimes barely $50 on a whole plane’s worth of fuel.

The BBC estimates that the practice produced 18,000 metric tons of unnecessary carbon dioxide in 2018.

British Airways said in response that it would consider changing its process.

Visit Business Insider’s homepage for more stories.

Airlines are flying tons of unneeded fuel around the world to achieve often vanishingly small savings by not buying fuel in countries with higher prices, according to a BBC investigation.

The broadcaster detailed a process — known as fuel tankering — whereby planes carry much more fuel than they need for a trip.

Companies do this to avoid buying fuel in places where it costs more, according to the BBC.

But carrying more fuel makes a plane heavier, which increases the carbon emissions needed to fly it. The result is thousands of tons in carbon emissions that would otherwise be avoided if the plane refueled more frequently.

According to the BBC’s „Panorama“ program, which acquired leaked documents, extra fuel is carried even when the overall saving is very small — citing figures of as little as $52 saved on an entire plane’s worth of fuel.

The BBC investigation focused on British Airways, which it said produced an extra 18,000 metric tons of carbon dioxide in 2018 thanks to the practice. One metric ton is equal to about 1.1 tons.

The BBC said one flight to Italy carried almost 3 metric tons of extra fuel, adding 600 kilograms of carbon emissions to save the airline less than £40, or $51.

British Airways told the BBC that other airlines did the same thing. The BBC said it had evidence that easyJet also did. Business Insider has contacted easyJet over whether it used fuel tankering.

Eurocontrol, the body that coordinates air traffic control across Europe, estimated in a June report that airlines saved £229 million, or $293 million, a year through fuel tankering in Europe, at an environmental cost of 901,000 metric tons of carbon dioxide as a result.

In response to the BBC report, the CEO of British Airways‘ parent company, the International Airlines Group, announced a review.

The Guardian reported that the group’s CEO, Willie Walsh, said: „We continue to do tankering today. We’re challenging that, we’re asking ourselves whether this is sustainable, and whether we should be pricing in the environmental impact of that.

„Clearly the financial savings incentivize us to do tankering. But maybe that’s the wrong thing to do.“

Willie Walsh IAG CEO REUTERS/Clodagh Kilcoyne

British Airways told the BBC that it was a common practice for airlines and that it mainly did it on short-haul flights „where there are considerable price differences between European airports.“

The airline also told the BBC that the extra emissions generated by it were about 2% of the total extra emissions generated by all airlines that were using fuel tankering in Europe, based on research by Eurocontrol.