Does it matter to your carbon footprint whether you’re flying across the Atlantic or the Pacific?

In 2015, the ICCT released a white paper comparing the fuel efficiency of 20 major airlines operating in the transatlantic market-specifically, nonstop passenger flights between North America and Europe. Earlier this year, we expanded on this previous work and released a similar study of the transpacific market.

A few revealing comparisons between the two can be drawn. Over 155,000 flights were used to quantify the fuel efficiency of the 20 airlines operating transpacific flights, less than half the number of flights analyzed for the transatlantic ranking. The average length of a transpacific flight was 10,738 km, which was 62% longer than the average transatlantic flight. Comparing capacity, the Pacific market had 35% fewer available seat kilometers than for the Atlantic market, but larger aircraft. The average aircraft utilized between the US and East Asia and Oceania had 295 seats, compared to 263 seats for the average aircraft between North America and Europe. This is unsurprising; longer flight distance correlates with larger aircraft.

Figure 1 shows both the 2014 transatlantic and 2016 transpacific airline fuel-efficiency rankings. Across the Atlantic, Norwegian ranked first, with an average fuel efficiency of 40 pax-km/L. British Airways was least efficient, burning 51% more fuel per passenger kilometer, on average, than Norwegian. Across the Pacific, Hainan Airlines and All Nippon Airways (ANA) tied for the top with an average fuel efficiency of 36 pax-km/L, while Qantas Airways ranked least-efficient at 22 pax-km/L.

Figure 1

The 64% fuel-efficiency gap between Hainan and ANA and bottom-ranked Qantas on transpacific operations in 2016 was wider than was observed on transatlantic routes in 2014. One main driver of this was freight carriage, which explained almost half of the variation in transpacific fuel efficiency compared with just 9% for transatlantic flights, as shown in Figure 2. Increasing the total payload, between both passengers and freight, increase the fuel efficiency of an aircraft per unit mass because the aircraft is used closer to its maximum capacity. The effect of freight on transpacific fuel efficiency is demonstrated by ANA, which tied for first in the ranking despite having the most premium seating, the lowest seating density, and one of the lowest passenger load factors.

Part, but not all, of this can be explained by the fact that the average freight share of total tonne-km for transpacific operations was 25%, higher than the 18% average for transatlantic flights.  But a difference in methodologies suggests that the transatlantic ranking may have underestimated belly freight as a driver of the fuel-efficiency gap across airlines.  For the transpacific ranking, reported freight carriage from the U.S. Department of Transportation’s Bureau of Transportation Statistics (BTS) T-100 database was used to estimate fuel efficiency, while for the transatlantic calculations, freight carriage was estimated for all carriers based on BTS T-100 data for only the U.S. carriers. This was done to integrate flights to and from Canada, which do not report data to BTS, into the rankings.

Figure 2

In both rankings, seating configuration, or seating density, also influenced airline fuel efficiency. The seating densities on transatlantic operations were generally higher than for transpacific operations, with a higher share of premium seats-first class and business class-for transpacific flights. Given that premium seats are, on average, three times as carbon-intensive as economy seats, this could be one explanation for why average fuel efficiency for transpacific operations, at 31 pax-km/L, was lower than for transatlantic operations, at 32 pax-km/L. Comparing two airlines that topped their respective rankings, both Norwegian and Hainan flew a majority of their flights to and from the U.S. on Boeing 787 Dreamliners. However, the number of passengers transported differed. Norwegian filled 86% of its seats (of a maximum 292 or 344, depending on aircraft variant) compared to 81% seats for Hainan (of a maximum of 213 or 289).

On average, the three U.S. carriers-American, Delta, and United-were more fuel-efficient on transpacific flights compared to transatlantic operations. This may be attributable to higher freight carriage across the Pacific, as well as aircraft choice. While these airlines used the same aircraft in both markets, Boeing 777s and 787 Dreamliners prevailed on the transpacific routes, while the older and smaller Boeing 767s were more widely used on transatlantic routes. It would be interesting to see additional study of how airline fuel efficiencies compare between aircraft types in different geographic markets.

The transatlantic market has changed since 2014. Then, top-ranked Norwegian Air Shuttle served only 4 U.S. airports. Now, that number has risen to 13, with the low-cost carrier adding 2 more airports later this month. Both Delta and United retired their fuel-inefficient Boeing 747s in 2017 in favor of more efficient aircraft. The use of fuel-efficient Boeing 787 aircraft has increased. In 2014, 5 airlines completed nearly 3,000 U.S. arrivals and departures with the Dreamliner. Norwegian alone flew nearly that many flights with the 787 in 2016. The Icelandic low-cost carrier WOW air entered the North American market in 2015, and currently serves 10 airports in the U.S. and Canada; it plans to expand to15 airports by the end of May. And finally, American and US Airways merged, which will lead to changes like the optimization of aircraft on some routes.

With the changes in the transatlantic market, it seems that it may be time for an update of the transatlantic fuel efficiency rankings to see if increased competition by low-cost carriers and the delivery of more fuel-efficient aircraft have made a positive impact.