Airline Fuel Efficiency

Fuel is still one of largest variables in the airline cost base. The fuel bill is usually one of the largest items in the airline budget, if not the largest. Airline fuel efficiency is still an area where many improvements can be made. Practitioners of this art usually target 2-5%. Usually a 1% improvement on the fuel bill can justify the people who work on it. Sometimes, it can be the difference between profit and loss for the airline.

Almost every airline has done its homework to try and manage this cost. You will see many initiatives in those airlines aimed at managing fuel. From removing excess weight on an aircraft, to controlling extra fuel taken at the discretion of the crew. However, with the recent introduction of new technological tools, there has been many things that can and are being done to improve such efforts.


Purdue University published a comparison in 2014 that was very insightful, and showed Ryanair and Southwest had a lead in Airline Fuel Efficiency in short-to-medium haul operations. It is no surprise that they were also profitable.

The introduction of low-cost long haul showed that there is a significant advantage to be had in flying the efficient way. The International Council on Clean Transport (ICCT) showed that some transatlantic flying is being done with around 25% more fuel efficiency. Norwegian and WOW air led the way, more about that below

However, while being better than the competition is always a good thing. This doesn’t necessarily mean you are good. You could be equally bad, for example, just a little less. You could be helped or hindered by factors outside your control. Samoans, for example, are 10-15 kilograms heavier than average Americans, which are 10-15 kilograms heavier than Europeans.


When we talk Fuel Efficiency metrics, I always mention the mandatory bottle of water in some restaurants, you know the one. That same bottle is split two-ways or four-ways depending on your dinner party. While the cost of the bottle is the same, the cost per diner varies. Similarly, we use the same with fuel efficiency. Now imagine paying per glass from that same mandatory bottle. This is what we try to do.

We need to look beyond fuel consumption, at fuel consumed per unit of revenue generation. The airline makes money by carrying passengers, baggage, cargo and mail for a fee. It would be pointless to tell you that airline is burning 3 Liters of fuel per passenger. A passenger from London to New York should not weigh equally as passenger flying from Providence, RI, an hour away by air.

Airline Fuel Efficiency Metrics

So we include distance as well and we arrive at fuel per Revenue Passenger Mile (RPM) Revenue Passenger Kilometer (RPK) in the parts of the world that use that unit. An example would be Kg/RTK. Another way to represent it is Gallons per RPM which is popular in the USA. Pax-KM/Liter is also becoming common

Then, think about an aircraft that is carrying 100 passengers but no little luggage. Say, a business destination. Compare that with an airplane carrying 100 passengers in families on a vacation destination, maybe even with some cargo. The second example is definitely heavier and therefore burns more fuel.

A somewhat fair metric to look into is the Fuel burnt per unit weight. Something like Liters/Revenue Ton Kilometer (L/RTK). Ton is the unit of weight that is commonly being used to add up passengers to freight and baggage.

Are Airline Fuel Efficiency metrics improving?

In my old job, I use to tell them that waiting around for the next big thing to save us fuel is not acceptable. Composite materials in airframe and next generation engines are all nice and dandy, but theses apply across the industry and don’t give that competitive edge. It is good for the flying public as it drives prices down, it also is good for the environment.

Airline Fuel Efficiency improved by around double in the past few decades.

It is widely noted that aircraft are getting more efficient all the time. This is mainly driven by new and more efficient aircraft and new technology. In fact, it would be worth noting that efficiency has improved by around 0.5%-2% per year every year since 1960. We now spend half as much fuel carrying the same load for the same distance. This is remarkable for the airline industry as a whole

So just buy newer aircraft?

Well yes, and no. Yes, airlines proved that new aircraft usually have a good return on investment. However, this will explain why Virgin Atlantic and Norwegian -both B787 users- have a 20% difference in efficiency

Transatlantic Fuel Efficiency Ranking published by ICCT. Showing ranking for operation crossing the Atlantic based on carrying passengers a weighted distance and how much fuel that consumes.
Transatlantic Fuel Efficiency Ranking published by ICCT. Showing ranking for operation crossing the Atlantic based on carrying passengers a weighted distance and how much fuel that consumes.

Technically, they use different variants of the same aircraft, so 1-2% is the difference that should be seen. This difference is explained by a number of other issues.

Seats in Airline Fuel Efficiency

The aircraft has a basal fuel efficiency and then burns based on load burns more. You burn more and fly in lower altitudes the more passengers you pack on the aircraft. Lower altitude means more dense air (more resistance) and more fuel burn. That is all correct.

However, that is all minute in comparison to the bigger picture, having more passengers on an airplane is still more efficient. Thus, a higher load Seat Factor (higher percentage of seats occupied) and more densely packed seats creates more efficiency.

The two main drivers of [Airline Fuel Efficiency Difference] were aircraft fuel burn and seating density, which combined explain nearly 75% of the variation in transatlantic fuel efficiency.

Two low-cost carriers—Norwegian, with its very
efficient Boeing 787 Dreamliner fleet, and WOW air, with its densely-packed Airbus A321-200 aircraft—topped this fuel efficiency ranking.

ICCT in the Transatlantic Fuel Efficiency Ranking 2017
ICCT will tell you that these are the four contributors in fuel efficiency. While they are right these are only the major ones.

The ICCT also did a similar report on transpacific flights and they determined the most important factors. However, experience will tell you that operational procedures can be in the factor of 2-5% of fuel consumption. I have yet to see an Operations Boss or an Airline CEO that can pass on such savings.

Airline Fuel Efficiency vs. Cost Efficiency

Cost Index

One thing most modern aircraft need is a cost index. The Cost Index is a measure of how much fuel the aircraft needs to spend to recover time. Or how fast should the aircraft fly in more simple times.

Think of it this way. What if I slow down the aircraft enough and save a bunch of fuel, wouldn’t that be nice. What if the in that same discussion, we see the people from network planning. The people who want to utilize the aircraft more, and see it get there sooner. It would be hard to convince them of giving you 15 more minutes on the on a long-haul to slowdown the aircraft.

What if, also, in that room, was the maintenance people, who see you effort to reduce fuel consumption as a extra cost to them when they are trying to get more flights out of their components. One component that should last 500 hours, for example, is being changed every 400 flights now instead of 450

There is a way to balance these conflicting interests and it is called the Cost Index. Managed well, you will notice a corporate relief at you efficiency efforts.


Tankering is a process by which you take fuel with you on the way going to fly you on the way back. Think of it as filling up in a cheaper gas station or before an expected price change.

Some airlines manage to get preferential prices at their home base because of good procurement. Others manage to get it because of a volume discount (bulk buying). Some Airlines will fly a big jet on a very slim route in order to load it with fuel at cheaper prices and fly it back to base. They can then use that cheaper fuel for another flight.

It is profitable and usually a good idea. However, it will impact your fuel burn on some sectors as tankering causes aircraft to be heavier and thus burn more fuel

A look from the outside

In every Airline Fuel Efficiency consultation I saw, when you ask the attendees 10 questions, you realize that there is a significant part of the saving that is not being realized.

I have a list of twenty to thirty that I use and a sizable questionnaire that I ask to be filled before I get to the consultation, but here is a few as a sample:

-What is your average APU minutes per sector ?
-What is your average taxi time at base for the peak hour ?
-When was the last meeting with your local ATC?
-What is your contingency policy?
-What is your alternate policy?
-How far does you average descent start from base ?
-When was the last cost of time calculated ?

Usually by the time these questions are answered there is a few hundred thousand to a couple-of-million of savings waiting to addressed.

Please follow and like us:

Author: Radi Radi

Taxpayer | Husband|Father| Flying enthusiast| LFC fan|MRI|AMRMetS |Lefty|AvMP | View all posts by Radi Radi

Leave a Reply

Your email address will not be published. Required fields are marked *