New Report: Fly Slower, Higher, Only Long Haul For Environment

A new report has a solution to reduce emissions by air travel: fly slower at higher altitudes and eliminate short haul flying. This should totally work. 

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The “Future” of Sustainable Aviation

Cambridge University released a report that envisions the future of aviation in a sustainable environment.

But not really of course, it simply explores ways to reduce carbon emissions but not eliminate them. Aviation is one of the world’s most carbon-intensive industries, but responsible for a less significant share of global emissions than most imagine (about 8% of consumption.) As the sector continues to grow, the challenge of reducing its environmental impact becomes increasingly pressing. The University of Cambridge study highlights several strategies to make aviation more sustainable, including flying at slower speeds, introducing newer planes, adjusting flight altitudes, and preparing for rising ticket prices.

The real struggle is matching obtainable environmental objectives without killing the industry, and damaging global economies.

Slower Planes: Cutting Fuel Burn at the Cost of Time

One of the most attention-grabbing suggestions in the study is to reduce flight speeds by about 15%. The report claims this could lower fuel consumption by 5 to 7%, contributing significantly to the industry’s sustainability goals. However, this change would come with a cost—longer flight times. For instance, domestic transatlantic flights could be extended by as much as 50 minutes.

The introduction of slower planes would require new designs and a “whole systems process change,” meaning airports, airlines, and manufacturers would need to collaborate extensively. While this solution promises environmental benefits, the practical implications—such as managing longer flight times and maintaining productivity—present a logistical challenge. Although the study suggests that reduced airport waiting times could offset longer flight durations, it doesn’t specify how such efficiencies would be realized.

A 15% increase in flight time would have additional effects across the system that are not accounted for in the study. For example, departures and arrivals would have to stretch even earlier in the morning to even later at night. For most of the US, a connection is involved, so increases in travel time would be doubled to account for that connection time.  Ultimately, to implement this airlines would require more planes and fuller flights when they already operate at near capacity. If we examine one nonstop flight that only takes a little bit longer, it doesn’t seem that bad, but when that spills to an entire additional jet that needs to be added to the schedule and an already congested airspace, does that continue to help? Unlikely.

For what it’s worth, increased labor costs would be further exacerbated by longer flights. That means more staff members will have to be hired adding training costs and labor costs to the longer flight model. An increase of 15% longer flight times when the study was performed doesn’t accurately reflect labor contracts that are 30%+ higher than just a couple of years ago, then add the additional hours of work.

Newer Planes

In addition to slower planes, the study emphasizes the need for newer aircraft. Replacing older planes with more fuel-efficient models could reduce fuel consumption by 11 to 14%. However, achieving this would require halving the average fleet age from 30 years to 15 by 2050, which demands a significant increase in aircraft production.

Boeing and Airbus, the industry’s leading manufacturers, already plan to double production by 2050. Still, the study suggests that a third manufacturer might be necessary to meet the demand. While the scale of this task may seem daunting, the report notes that aircraft production during World War II demonstrated the industry’s capability to rapidly scale up in a time of crisis.

What the study, again, neglects to consider are the current struggles in delivery of aircraft. Airbus has an engine issue slowing deliveries, Boeing has a litany of trouble with certifications for both the 737-MAX and 777-X airframes. The delivery schedule is close to a decade out for some new orders as it is now. And the study fails to acknowledge that additional manufacturers already have a position in the market with Embraer for example, but COMAC could also help deliver airframes sooner, probably much faster than European and American builders. The existence of alternatives is not the issue (though in wide-bodies it remains a two-horse race), the market has spoken.

Avoiding Contrails

Contrails—those white streaks left behind by airplanes—contribute to climate change, with a warming effect that could rival aviation’s CO2 emissions. The study proposes an initiative called “Operation Blue Skies,” which recommends adjusting flight paths to avoid regions known as Ice Supersaturated Regions (ISSRs), where contrails form. By tweaking altitudes, airlines can minimize the formation of contrails, thus reducing their environmental impact.

While these altitude shifts may go unnoticed by passengers, the associated costs might not. The study estimates that airlines would need to increase ticket prices by about 1% to cover the additional fuel and air traffic control costs required to avoid contrail-heavy areas. However, the environmental payoff—lower climate impact from contrails—far outweighs the minor fuel burn increase from these adjustments.

Rising Ticket Prices: The Cost of Sustainable Aviation Fuels

The transition to Sustainable Aviation Fuels (SAF), hydrogen-powered aircraft, and other eco-friendly alternatives is another key element in aviation’s path to net-zero emissions. However, these greener fuels come with a price. The study suggests that by 2050, ticket prices could increase by 33 to 34% for hydrogen-powered and Biomass-to-Liquid (BtL) SAF flights. More complex but efficient fuel options could push prices up by as much as 81%. This does not account for the increased labor costs outlined elsewhere in this post.

Currently, SAF accounts for a mere 0.2% of all jet fuel used in the industry, making it a critical area for development. The UK government has mandated that airlines increase SAF usage to 10% by the end of the decade, but the aviation industry warns that production levels are far from sufficient. Virgin Atlantic’s Holly Boyd-Boland notes that SAF production would need to be scaled up by 80 to 100 times the current levels to meet future demand. Government action and investment will be crucial to achieving this ambitious target.

Domestic Flight Bans: Reducing Short-Haul Emissions

Another potential solution to reducing aviation’s environmental impact is limiting the demand for flights, especially domestic routes. France has already banned domestic flights on routes where rail alternatives exist that take less than 2.5 hours. This approach cuts emissions by up to 95% per passenger per kilometer. However, domestic flights account for just 7% of global aviation emissions, with most occurring in the United States. Outside of the northeast, trains are not a practical alternative. If a short haul ban was mandated in the US as it is in France and Germany, many would resort to driving which is far worse for the environment than a train. Either a short haul ban doesn’t do what the study thinks it will do, or they didn’t consider the practicality of solving the matter.

While domestic flight bans may not provide a significant reduction in global emissions, they demonstrate a shift in how governments and regulators are thinking about sustainable travel. Encouraging the use of alternative transportation methods, like high-speed trains, could play a role in reducing aviation’s environmental footprint, especially on short-haul routes.

Conclusion

The extensive study remains short sighted and, frankly, mostly unfamiliar with the cause and effect of these policies. It assumes that world governments will back (in the hundreds of billions if not trillions of dollars) the deep infrastructure changes required to implement these fixes. It makes flying impractical for millions if not billions of people worldwide and would ultimately collapse the market costing millions of jobs globally. Travel also provides much needed GDP growth, foreign spending, and support to local small businesses in the tourism trade.

If changes are going to be made, they have to be practical, scalable, without disenfranchising the public footing the bill both in taxes and much higher fares. It’s a good thing this report was produced digitally, because if not, the waste alone would outweigh any actual beneficial outcome. And it makes for terrible toilet paper, though that’s its most practical service.

What do you think?