WestJet announced a "new state-of-the-art money saving feature" aboard its flights. It was introducing "air mixed with helium in the ventilation system to lighten the weight of the aircraft."
Helium is approximately 85 per cent lighter than nitrogen, which accounts for 80 per cent of the air we breathe. With a maximum takeoff weight of more than 150,000 pounds, adding helium to the air mix will provide fuel savings of approximately three to four per cent on board WestJet’s Boeing Next-Generation 737s. This will, in turn, allow WestJet to pass the savings on to its guests.