Which airline is the first in the World to use sun-to-liquid fuel?

Sun-to-liquid (solar) fuel is a synthetic kerosene made by using concentrated solar heat to split carbon dioxide and water into syngas, which is then converted through Fischer-Tropsch synthesis into a liquid hydrocarbon fuel chemically identical to conventional jet fuel - a carbon-neutral, drop-in replacement that needs no change to aircraft engines or airport fuel infrastructure.

The Swiss company Synhelion pioneered and commercialised this solar-fuel process. Swiss International Air Lines (SWISS) partnered with Synhelion and became the first airline in the world to integrate Synhelion's solar kerosene into an actual flight operation, marking the debut of sun-to-liquid fuel in commercial aviation.

Contrast with the other carriers named:

• Singapore Airlines' sustainability push centres on sustainable aviation fuel (SAF) refined from used cooking oil and waste fats, not on solar-thermal kerosene.

• Japan Airlines has trialled SAF blends made from conventional bio-feedstocks, a different pathway from concentrating solar heat to synthesise kerosene.

• Qantas Airways sources SAF from feedstocks such as tallow and agricultural residue, not from capturing solar heat to manufacture kerosene.

So the carrier that first integrated sun-to-liquid (solar) kerosene into flight operations is Swiss International Air Lines (SWISS).