The Greenest Airlines: Who’s The Most Fuel-Efficient, And Why?

A new study by Brighter Planet has analyzed data from sources such as the United States Bureau of Transportation Services, the US Federal Aviation Administration, and the European Environmental Agency to reveal which major airlines are operating the most fuel-efficient and environmentally-friendly flights. The study found that fuel efficiency varies greatly among airlines and aircrafts, a conclusion drawn by analyzing five influential factors.

The study reviewed a decade’s worth of data, 130 million flight departures and 9.7 billion passenger boardings from the world’s 20 largest airlines by passenger volume, considering fuel efficiency, passenger load, seat density, freight share, and distance.


European budget carrier Ryanair came out on top, while American Airlines’ offshoot airline, American Eagle, ranked last. Hong Kong-based Cathay Pacific came in second, with European no-frills airline easyJet  close behind. Continental and United, which are scheduled to merge later this year, were ranked third and fourth and were the top American carriers. Domestic travel was found to be less efficient than international travel, but these results are skewed by the fact that domestic flights are often short and operated by regional carriers with small aircrafts, two characteristics that negatively affect efficiency. 

In the study, Brighter Planet divided the total amount of fuel consumed by the number of passengers on each flight to calculate the cost of fuel per passenger, which determines the overall efficiency. These calculations rely on all five efficiency drivers, which come together to form a complete and detailed picture of carbon emissions in the airline industry.

Fuel efficiency is tied to the aircraft model, as larger airplanes require more fuel than smaller models. Larger aircrafts burn more fuel, presumably making them less efficient. However, passenger load significantly affects fuel efficiency, as a large plane with a full passenger load will be more fuel-efficient than a small plane with few passengers, as the cost of fuel per person rises if there are less people on the flight.

Seating density is also tied to each particular aircraft, as airplanes with more seats use less fuel per passenger and are thus more efficient. Although all aircrafts of a certain model – e.g., a Boeing 747-800 – are manufactured to be the same size, airlines can choose how many seats to fit on each plane, altering the seat density of each vehicle. An aircraft on top-ranking Ryanair and easyJet often will accommodate more passengers with a higher seat density than the same model on another airline that chooses to outfit its aircraft with a low seating density, such as British Airways, making Ryanair and easyJet more efficient. Seat density declines in aircrafts with a large first class section, as first class allows more leg room and less seats.

Freight share refers to the extra freight – besides airline equipment, passengers and luggage – that airplanes carry. Seventy-eight percent of commercial flights load mail and other cargo onto the plane, increasing efficiency by carrying cargo that would otherwise consume more fuel if flown separately. Most flights, though, only carry up to 5% of freight share, making this factor arguably the least significant.

Distance has the greatest effect on how efficient a flight is, as it impacts how economically the fuel is used. With the exception of the longest overseas flights, short flights are less efficient than long flights, because takeoff and landing require more fuel than cruising at altitude. Two short flights consume more fuel than one long flight, as the takeoff and landing is doubled – e.g., a nonstop flight from Los Angeles to New York City will consume less fuel than the same flight with a layover in Dallas, as it is necessary to land the plane in Dallas and take off again, two fuel-guzzling moves.

Airline fuel efficiency has increased by 20 percent over the last decade, largely due to airline competition and the rising cost of fuel on a global scale. There is no evidence to show that ticket price is related to efficiency, a good sign indicating that more efficient flights aren’t charged a premium. Air travel is estimated to contribute about 2 percent of global carbon emissions, and 3 percent of both European and American carbon emissions. The industry consumes 75 billion gallons of fuel every year, releasing 3 trillion pounds of CO2e into the air.

Brighter Planet CEO Patti Prairie stresses that air travel can be an efficient means of transportation, and says that the findings demonstrate that “businesses and individuals don’t necessarily have to cut out air travel or spend more time and money to be more environmentally sensitive, they just need better carbon intelligence.” Passengers can decrease their carbon footprint while traveling by choosing full flights or peak dates, large aircrafts, and nonstop flights, and by flying economy class.

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