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.

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Pilot Error is the leading cause in Airline Crashes

This is hardly news, Pilot Error is still up there as the number 1 reasons airplanes crash. Every study that looks into this concludes the same this. 70-85% of airline crashes are attributed to Pilot Error.

In the heyday of aviation, machine fault was usually responsible for crashes. According to Boeing, 80% of crashes were attributable to machine causes in 1903. Technology improved and now only 20% are now attributable to machine error. In my experience, Pilots have a lot more work to do to be safer operators.

According to Boeing, Human Causes are responsible for 80% of Airplane crashes today. Pilot Error is within that category
According to Boeing, Human Causes are responsible for 80% of Airplane crashes today. Pilot Error is within that category

It is safe!

Before I am accused of fear-mongering, let me be clear of what the data says.
In the UK, the death rate per billion (yes, billion) Kilometers flown is around 0.05 deaths. Compare that to the bus (the next safest mode of transport) and you get 0.4. Meaning you are 8 times as likely to die on the bus than on an airplane for a comparable journey.

Planes don’t compete with busses, though. A fair comparison would be with rail. 0.6 is the magic number for rail transport and that is 12 times more likely than airplanes.

In perspective, That means 5 people die every 100 Billion (yes, I know)kilometers flown on an airplane. So safety is not in any immediate risk.

In April IATA released its report for 2019, it is important to understand that numbers of accidents are falling with fatalities falling too. On average, a person would have to travel by air every day for 535 years before experiencing an accident with at least one fatality. If you were involved in an accident in 2019, there was about a 15% chance that you would die.

There were 8 accidents with fatalities in 2019 with 50% of those accidents responsible for 80% of the fatalities.

Also, the accident rate is continuously falling, the number of accidents is staying the same or marginally falling.

According to Airbus, while the average number of fatal accidents is slightly falling, the accident rates are dramatically falling
According to Airbus, while the average number of fatal accidents is slightly falling, the accident rates are dramatically falling

Now, with that clear. First lets talk more about the other humans in the chain.

Human Causes is not always Pilot Error

The easiest example to think of is maintenance error, if something is fixed improperly or replaced incorrectly then it counts as Human Causes. Airplanes are complex machines and as such contain thousands of components and thousands of tasks need to be done to keep them flying. So, something is bound to go wrong, miniscule as the odds are.

The guideline for maintenance staff are extensive and the qualification process very thorough. The people who release the aircraft into service or allow them to depart after a check or a fault are experts in their own right. However, it does happen that with long hours and continuous tasks something slips through the cracks.

Another human cause can be the humans in Air Traffic Control. They are the ones who tell the pilots to go up and down, left and right. They are also often under pressure and stress. Their main job is to make sure the airplanes are not hitting each other. However, if you watch this, you will know that mistakes happen.

Even the airlines themselves can have human causes inflicted upon the flight, whether it is poor oversight, insufficient training or even bad scheduling. This can further complicate the issue

The devil is in the detail

Most of the media reporting on pilot error relates to total accidents or total fatalities. This includes many private pilots with a much shorter experience log and less complex requirements on how to stay current with flying.

73% percent of accidents have errors by Cockpit Crew as a contributing factor. What does that mean? Think of it this way, if an engine blows up at take-off, like it did with Sully, and the pilot mishandles the exercise or does something not exactly by the book, then pilot error gets a mention. No matter how many other factors could have been engaged in the situation. Terrible weather, long working hours, inadequate rest or anything else. Pilot Error will still show as a contributing factor.

I am not absolving pilots of their errors. Pilots are humans, humans make mistakes. Around 50% of Airline accidents that lead to fatalities are cases were the pilot error was the primary cause. Even then, within those 50%, the accident rates vary considerably.

The number changes with relationship to the type of flying. The United states has clear data on part-135 (think charter and smaller operators) versus Part-121 which is regular airlines. “For the 5-year period 2003–07, the crash rate for Part 135 was more than twice the rate for Part 121” says this study. Which means you are twice as likely to have an accident flying on a chartered airplane versus flying on a scheduled airline.

Another factor is the generation of aircraft flown. Newer generation aircraft have an accident rate that is around a third of the previous generation.

According to Airbus, Accident rate in relationship to aircraft generation
According to Airbus, Accident rate in relationship to aircraft generation shows a 9-fold improvement over the past two generations

Importantly, it is worth noting that pilot experience is important in determining accident rates as well

Where are you flying and how experienced are your pilots

Johns Hopkins university studied the issue in 2002 and their findings are not exactly surprising to pilots. Pilots with less than 5,000 hours of total flight time were nearly twice as likely as their more experienced counterparts to be involved in a crash. Many other studies since have agreed with the finding that experience matters.

5,000 hours is an arbitrary line to draw, however, it resonates with a large number of airlines with respect to experience needed to become a Captain. This is usually the bare minimum. Most have more or much more depending on the airline and the rate of growth of the airline and the depletion of pilots on the other side. However, most of the flying public would agree that more experienced pilots in the airlines makes more sense.

The environment the pilot works in, greatly influences the accident rate. It is well established that the airline pilot fly in matters, but also the part of the world that the airline is based in also matters. There are many regions in the world where oversight by the regulator and the general operating atmoshpere help a safe operation.

Other regions, especially in Sub-Saharan Africa and the old block of countries that made up the USSR, are continuously facing issues with oversight. I have seen lack of resources to invest in inspections and training for the staff on the government’s side. I have seen airlines push their staff to work more than what is usually acceptable in search of efficiency.

A pilot in Africa is more than 10 times as likely to have an accident as a Pilot in the Middle East and North Africa
A pilot in Africa (AFI) is more than 10 times as likely to have an accident as a Pilot in the Middle East and North Africa (MENA)

Pilot Error as a sum of their threats and errors

Every good airline emphasizes Threat and Error Management (TEM) for their pilots. TEM has shown incredible results in reducing accident rates when applied. It also gave us valuable insight on what are the highest threats.

An IATA study showed that meteorology was a threat factor in around 48% of fatal accidents and 36% of all accidents between 2015-2019. Meaning pilots where caught unaware of the weather they were going to face.


Let’s compare two flights, as per the following table

Pilot APilot B
Operation TypeScheduledChartered
Generation of AircraftFourthThird
ExperienceMore ExperiencedLess Experienced
Geographic LocationMiddle East to EuropeAfrica to Russia
Pilot A is statistically a 100 times less likely to cause an accident than Pilot B

Based on what we learned above. Pilot B is much more likely to cause an accident than pilot A. Even if they are both equally qualified and skilled.

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Flight Laundering

Jordan is shaping up to be the flight laundering station between the Gulf capitals and Israel

There was a time when the face that Jordanians overfly Israel and Palestinian territories was a novel concept. Whenever we sat in ICAO meetings in Cairo or some other capital, the word “Israel” spoken made many uncomfortable. The attendance evaded that by saying “Lima Lima Lima Lima.” 

It was not a Peruvian patriotic chant or some sort of debilitating stutter. It was a reference to the Phoentic pronunciation of LLLL. The ICAO code for Tel Aviv FIR, the airspace that Israel manages.

People where uncomfortable acknowledging the world Israel meant something now. I always thought it was a rather “Head-in-the sand” approach to dealing with the problem

Laundering as it where the word Israel or Tel Aviv and cleaning it into the cacophonous  “Lima Lima Lima Lima” always seemed ridiculous to me. 


That was something that we got used to, public pressure to conform to the official line of no recognition and no peace was always there. On the other hand, many rumors of normalization went on for years on end.


LLLL Airspace
Tel Aviv FIR as part of the EUR region and Paris office

Tel Aviv FIR falls under the Paris office in ICAO, meaning it is considered in EURope. While a stone-throw away (no pun intended) from Europe, Israel is solidly in the Middle East, however, it was never welcomed in the MID region which covers the Middle East. 


The move to the Paris office was logical to the Middle East and the Israelis. So much so that a few years later, Israeli airspace is now under a comprehensive agreement with the Euro-control.


That was then, this is now. 


Cl-604 landing in Marka
The bizjet landed with a squawk code of 0431

On Tuesday the 22nd of October, an airplane landed in Amman’s Marka Airport on 19:09 GMT.


Two minutes later the aircraft departed the same airport in the opposite direction and with a different squawk code. The two minute stop could be pushing the edge of what is legal as it doesn’t seem the flight has truly terminated to require a new code. 


Preparing for a proper departure in a jet aircraft usually needs no less than 5 minutes at least and usually around 15-20 minutes. Being a night flight necessitates more caution. Someone was in a rush 


Departing Cl-604 from Marka
The aircraft departing two minutes later with 0710 squawk

To land on Runway 06 in Marka is not normal and someone was coordinating their operation intently.


A squawk is a code that allows Aircraft to talk to secondary radars. The series of codes allocated to each country can usually be a tell-tale of the origin of the aircraft 


This makes it seem that the flight originated from Amman. For all intents and purposes, someone put an effort to try to make it look like the aircraft originated from Jordan.


The aircraft is US-registered and media reports are actually pointing to Mark Esper’s visit to Saudi and a possible meeting including Israeli officials

tweet from Avi Scharf, an Israeli journalist, actually made this laundering public. The journalist seems to have a tracking passion. Many of his twitter posts point to FlightRadar24 images and some images of what seems to be a flightfeeder


A previous tweet by Avi explained that this flight laundering is common place. In the strained public perception of Israel by citizens of gulf countries, it seems to legitimize the flight and make it clean. 


Many other media outlets also referenced the same event to point to the possibility of Netanyahu being on the airplane


The aircraft also did a small stop on the way back in Marka Airport, again changing the squawk code. This time a more normal turnaround of 20 minutes ensued. 


These antics were not envisaged when the air transport system was designed. It does mean that the operators and pilots of such flights are usually put under more pressure and this can lead to undesirable results, if not incidents and accidents.


The local regulator in Jordan will find itself helpless. The political pressure to maintain the relationship with Saudi Arabia and Israel at the bare minimum will override any bureaucrat desire to apply simple and well-established procedures that guarantee safety. Flight Laundering seems to be the equivalent of money laundering in politics.


 Peace, Out!

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