IAG chief Willie Walsh has highlighted the conflict between operational, economic and environmental considerations arising from the policy of tankering fuel.
Tankering involves transporting more fuel than required for a flight, for various operational considerations.
Speaking during a capital-markets briefing on 8 November, Walsh said that IAG undertook tankering to avoid "sporadic" fuel uplift at some airports, or to meet timelines for turnaround.
He adds that IAG also tankers fuel for cost reasons, notably to offset the differential in fuel prices between airports – mentioning that fuel at Glasgow is 25% more expensive than at London Heathrow.
IAG declared in October that it would commit to achieving net-zero carbon emissions by 2050, the first airline group to make such a pledge. But Walsh points out that operational and environmental targets are often contradictory.
He cites a Eurocontrol analysis from June this year which examined the impact of tankering at the level of the 44 member states of the European Civil Aviation Conference.
In the ECAC area about 16.5% of flights are able to perform full fuel tankering and 4.5% partial tankering.
This results in the burning of an additional 286,000t of fuel annually and, as a result, the generation of 901,000t of "unnecessary" additional carbon dioxide emissions, says the analysis – the equivalent of 2,800 round trips between Paris and New York.
But Walsh also points out that this tankering represents a net saving to airlines of €265 million ($290 million) per year.
IAG accounts for around 2% of the 901,000t of additional carbon dioxide produced through tankering, he says.
The Eurocontrol analysis says tankering "could offset" the benefit of initiatives to save fuel and reduce carbon dioxide emissions, and adds that the practice of tankering is "questionable".
Walsh says IAG is having to consider such issues in its operational strategy, and looking at whether the company "should be pricing in environmental impact", admitting that some routes which make "commercial sense" do not necessarily make "environmental sense".
He underlines IAG's efforts to integrate environmental considerations into its business strategy. The company, he adds, is assessing the value of incentivising management, to make sure it is "not incentivising the wrong behaviour".
"We don't dispute the science [of climate change]," he stresses, adding that IAG intends to increase its transparency in relation to its environmental practices, through measuring, monitoring and auditing. "We're going to be completely open about what we do."