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If you’re looking for a way to make your flying more environmentally friendly, the easiest option is to buy carbon offsets. By doing that, you’re donating to organizations that work to lessen the impact of carbon emissions — which airplanes produce in vast amounts — on the atmosphere. That’s why we’ve recently covered the basics of carbon offsetting as well as airlines that offer carbon offsetting options to passengers.

Another way is to fly airlines that are carbon-efficient. This week, in the third article in a four-part series on carbon offsetting and environmentally friendly travel, we’re looking at the world’s most and least carbon-efficient airlines, using the 2017 Atmosfair Airline Index. We’ll discuss how to use this index and other information to choose carbon-efficient flights.

In This Post

Airline Index

The Atmosfair Airline Index ranks airlines based on how their flights perform when compared with the technically achievable optimum. The most recent index (PDF document), published in November 2017, uses the latest available data (from 2015) on worldwide aviation, covering 92% of routes worldwide.

Atmosfair ranks each airline on short-haul (less than 497 miles), medium-haul (497 to 2,361 miles) and long-haul routes (more than 2,361 miles). In order to find the most carbon efficient flight, you should calculate your flight distance and then select the airline with the best performance ranking for that distance that operates a direct flight on that route. Granted, an airline with a high index could operate an inefficient aircraft on your specific route, but the index provides a general understanding of which airlines are more and less carbon efficient.

The CO2 emissions calculation (PDF document) considers aircraft types, engine types, use of fuel-saving winglets, seating capacity, freight capacity and occupancy for each airline on each route. The airline with the worst emissions on a route gets a performance score of zero for that route. Then, the technically achievable optimum is calculated and the performance scores for all of the other airlines on that route are linearly interpolated. Each airline’s overall score is a weighted average across all of its routes.

How to Choose Flights

Many flyers choose flights based solely on price, airline or schedule. However, if you have some flexibility, you can choose options that are more carbon efficient.

  1. Fly direct. Flying direct, even on less efficient aircraft, is more carbon efficient than taking multiple connecting flights on efficient aircraft.
  2. Fly on carbon efficient aircraft. Atmosfair’s 2017 Airline Index press release (PDF document) suggests travelers choose flights on efficient aircraft such as 787-9s, A350-900s and A319s with sharklets. Otherwise, use Atmosfair’s calculator to compare various aircraft on your specific route.
  3. Fly on efficient airlines. If you don’t want to bother determining the actual aircraft type on your route, or most of the aircraft serving your route have similar carbon efficiency, do as Atmosfair suggests and use its rankings to pick the best ranking airline for your flight distance.

That said, here is a look at who was good and who was bad when it comes to carbon emissions.

The Best and Worst US Carriers

The world’s top 50 most efficient airlines in the 2017 Airline Index include 16 airlines from Europe, 10 from China and three from the US. Atmosfair’s report (PDF document) shows the complete results but for ease we’ve listed the performances indexes for US mainline carriers and their regional partners below. The best-performing US carrier, Alaska Airlines, is only number 14 worldwide.

Airline US Rank Worldwide Rank Overall Short-Haul Medium-Haul Long-Haul
Alaska 1 14 67.6 35.4 66.9 70.3
Delta 2 41 59.7 57.0 63.4 53.7
United 3 41 59.7 60.4 66.1 53.0
Hawaiian 4 56 57.0 51.9 58.0
American 5 66 55.1 49.8 62.4 40.1
Horizon (Alaska) 6 87 48.9 47.4 51.2
Ohana (Hawaiian) 7 113 38.8 38.8
Envoy (American) 8 119 32.8 30.9 34.0
United Express 9 120 32.0 32.2 31.9
Delta Connection 10 122 29.5 25.9 31.0

Alaska performed best among the US carriers due to dense seating and high occupancy levels across a fleet consisting mostly of efficient aircraft. (The more people sit on a plane, the lower the emissions per capita.) Inefficient 737-400s — which Alaska recently retired — are the main component that damaged Alaska’s performance index.

Delta’s performance index reflects a fleet consisting partially of efficient aircraft and partially of inefficient aircraft like MD-80s. Although Delta generally has high occupancy levels, it lost points since much of its fleet features less dense seating than average.

United earned points for a fleet consisting mostly of efficient aircraft and high occupancy on medium-haul flights. However, United lost points due to average density seating on medium-haul flights and below average density seating with only average occupancy on long-haul flights.

American’s fleet consists mostly of efficient aircraft, but American still has many inefficient MD-80s serving medium-haul flights. Its medium-haul aircraft usually feature average density seating, but seating density is below average on most long-haul aircraft. American earns points due to high occupancy on medium-haul flights but loses points due to only average occupancy on long-haul flights.

Except for Horizon on short-haul routes, the regional carriers perform significantly worse than the mainline carriers.

The Best and Worst Non-US Carriers

The top three carriers worldwide will be unfamiliar to most US-based flyers. TUI Airways from the UK, the world’s biggest charter airline, came in first overall. TUI performed very well because it flies efficient Boeing 737-800 and 787 aircraft, puts lots of seats inside them, and flies often full. China’s West Air came in second overall. West Air only flies efficient aircraft with very dense seating and maintains very high occupancy. TUIfly from Germany, also a member of the TUI Group, came in third overall.

Below we include a table summarizing the performance of top carriers and more well-known carriers in the 2017 Airline Index report (PDF document).

To find the first big international carrier, you have to scroll down to number 13, where Dutch KLM placed thanks to a fleet of mostly efficient aircraft. The large world-spanning airlines tend to have much larger fleets, and therefore often tend to have older airplanes, which depress their ranking. That’s why its next-door rival Lufthansa, the biggest airline in Europe, placed only 65th — its fleet consists partly of older, inefficient aircraft, which it is in the process of retiring. That’s also why many US airlines rank so poorly, as their enormous fleets (and few orders for new aircraft following the early-2000s slowdown) result in long timelines for replacement of older planes.

The biggest airline in the world by international passengers carried, Emirates, operates a fleet with mostly modern aircraft. However, it placed only 111th because its aircraft have below average seating density and suffered from low occupancy when the study was conducted.

Airline Worldwide Rank Overall Short-Haul Medium-Haul Long-Haul
TUI Airways 1 78.9 59.8 79.5 77.7
China West Air 2 78.6 77.6 78.7
TUIfly 3 78.2 75.6 78.4 73.1
LATAM 11 72.3 69.5 75.9 64.7
KLM 13 68.1 62.1 67.5 68.9
EVA 29 62.1 62.8 69.5 57.1
Lufthansa 65 55.2 56.5 66.5 49.1
Etihad 82 49.8 58.1 56.3 47.2
ANA 89 48.1 62.7 61.7 27.1
Qatar 94 46.1 47.2 54.3 43.4
Emirates 111 39.6 34.8 43.8 38.7
Singapore 116 35.1 30.8 44.1 33.1

Low-Cost Airlines

Atmosfair believes low-cost airlines create a separate market in which ticket prices are often artificially low and hence create travel that wouldn’t otherwise occur. As such, the Airline Index assigns low-cost carrier letters related to their efficiency class but doesn’t provide performance indexes.

No low-cost carriers earned an “A” rating and only Scoot earned a “B” ranking. Most low-cost carriers received “C” ratings, including AirAsia, AirAsiaX, Frontier, Norwegian, Southwest and Spirit. A few low-cost carriers received “D” ratings, including Allegiant, JetBlue, Virgin America and WestJet. Just one low-cost carrier, Interjet, received an “E” rating.

Bottom Line

Atmosfair concludes that airlines with the best carbon efficiency use modern, efficient aircraft with high seating density and high rates of passenger occupancy.

One must keep in mind that the world’s best business and first class seats take up a lot of space and resources and often fly with low occupancy. Although taking a shower, having a suite with a real bed and lounge chair or visiting a lounge with a bar during a flight is appealing, all of these features significantly decrease seating density and increase aircraft weight.

In economy, most passengers salivate over flights with low occupancy so they can grab an entire row for themselves. Likewise, no one likes having to back into a miniature bathroom or squeeze into slimline seats with limited pitch on high-density planes. Although I don’t recommend purposefully booking flights with dense seating or almost full seat maps, I do recommend flying direct and/or on carbon efficient aircraft when possible, and using Atmosfair’s Airline Index as a secondary guideline.

If you want to read more about Atmosfair’s Airline Index, check out the website, 2017 press release PDF, 2017 report PDF and calculation method PDF.

Featured image by Justin Case/Getty Images

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