top of page

Join our mailing list

Never miss an update

Recent Posts



Have you got any thoughts on this feature?  Do you want to have your say?  If so please get in touch with us using the form below:

Thanks! Message sent.

Follow Us
  • Facebook Basic Square
  • Twitter Basic Square
  • Google+ Basic Square

Tankering fuel: the case for and against

On Monday evening, the BBC Panorama TV programme debated whether flying could become environmentally friendly. Given the myriad of climate-change campaigners that are employed by the broadcasting company and the bias that inevitably results, it was always going to be a stitch-up that would make air travel look bad.

Left: Refuelling can be an expensive business (Curimedia)

One aspect of modern airline operations that is not readily observed by the travelling public came in for particular scrutiny during the programme: tankering. Tankering is discussed in some detail in The Aviation Oracle’s forthcoming book So you want to start an airline. However, simplistically it is the practice of loading more fuel onto an aeroplane than is needed solely for its next trip - fuel that may be used during a later flight. Since energy is always consumed to move mass, it follows that a typical airliner will burn more fuel to move any excess fuel it carries. On average, an airliner will consume around 4% of any excess fuel it carries every hour, just to carry the fuel. So, loading a tonne (1,000kg) of excess fuel means burning an extra 40kg just humping it around. And using additional fuel increases carbon emissions, which was the gist of what the TV programme was getting so excitable about.

Accusations that the aviation industry isn’t taking climate change seriously abounded during the programme (the presenter suggested that if it was taking things seriously, tankering would be outlawed), and the print media also picked up on the story.

Meanwhile, in other shock news (conveniently not touched on at all by Panorama):

  • Buses have been found to be leaving depots in the morning full of fuel, rather than just carrying what is needed for the first trip and then being refilled during the day. This practice is widespread and results in increased emissions and pollution.

  • Motorists have been seen to fill up their tanks with cheap fuel even if they only make short journeys, and even go out of their way (drive extra miles) to buy at the lowest prices. These practices are also widespread and result in increased emissions and pollution

Seriously though, the harsh reality is that when ANY vehicle carries excess weight it consumes additional fuel and therefore pollutes more. UK motoring organisations even ran a campaign a while ago recommending we remove unnecessary junk from the boots of our cars, because dragging excess weight around increases fuel consumption - and maybe you’ve got the idea now, that in turn increases emissions. So, carrying more fuel than is needed for just the next trip produces more CO2 emissions whether it be a car, a train, a bus, a bicycle or even an aeroplane. Unfortunately, the eco-crusaders at the BBC choose not to discuss the adverse environmental impact of other forms of transport as they see air travel as the easiest and softest target. And even more sadly, the aviation industry does very little to proactively counter the accusations levelled against it, with head of IAG (parent of British Airways and Iberia) even going so far as to say he would review the firm’s policy on tankering, rather than explain why it happens and outlining its benefits.

Returning to the detail of tankering: what is it, and is it really all bad? The Aviation Oracle first encountered it thirty years or more ago, while working at a UK-based airline. Pilots were given a little grid, on the axes of which they could locate the departure and destination airports they were to fly between. At the intersection of the X-axis and Y-axis was a number – a fuel index. If the number was greater than one, fuel was more expensive at the destination and therefore sufficient for the return trip was best uplifted before the outbound departure. However, if the number was less than one then fuel was cheaper at the destination than at the point of departure and only a one-way quantity should be loaded before departure. The numbers in the grid were calculated to take into account the additional fuel burned by carrying excess fuel and were changed whenever the fuel prices fluctuated.

Here’s a simplistic example of how tankering can save money:

Fuel needed: 10,000kg each way, total 20,000kg

Fuel cost at origin: £1.00 per kg

Fuel cost at destination: £1.05 per kg

Total cost if fuel uplifted at each end: 10,000 x £1.00 + 10,000 x £1.05

= £20,500

Total cost if fuel uplifted for round trip: 20,000 x £1.00 = £20,000

Saving from uplifting round trip fuel at origin: £500

Additional fuel burned to carry excess fuel: 10,000kg x 4% = 400kg

Cost of additional 400kg of fuel used outbound: £400

Saving from tankering: £500 - £400 = £100

This hypothetical example only saves £100, but at a large airline many opportunities to save £100 (or even less on some trips depending on price variations) soon start to add up.

So, is airline tankering really that bad? The first thing to note is that tankering has been going on for decades. The essence of the matter was – and still is – that fuel prices vary across the globe just as they do at road-vehicle filling stations. And one of the reasons why airlines sometimes tanker fuel (remember, carrying excess fuel imposes a burden of additional consumption) is to save money compared buying it more expensively at remote airports – again, just as many motorists do on the road.

And there is good a reason why aviation fuel prices vary: it costs more to transport fuel to some airports than to others. The supply chain that moves fuel from refineries to more remote and distant airfields is complex and – here’s a key issue – that supply chain produces its own carbon emissions. Transporting thousands upon thousands of litres of aviation fuel to airports on [for example] a Greek island in itself produces emissions – emissions produced by the ships and trucks that carry the fuel to where it is sold to airlines. Indeed, fuel availability is limited at some airports, so tankering becomes an operational necessity. But no one has done research to determine whether surface transporting fuel to remote locations might be as or more polluting than airlines tankering fuel – and yet at present only airline tankering is getting flack from eco-warriors.

But its not just that. While fuel cost is a major factor, refuelling aircraft also takes time and tankering helps expedite aircraft turn rounds at remote destination airports. Fewer refuellings means aircraft spend less time on the ground, potentially enabling them to do more flights. Having more productive aircraft also ultimately comes down to money savings for the airline, which in turn helps to contain air fares at reasonable levels too. It’s also worth mentioning that carrying at least a little excess fuel is no bad thing when it comes to safety, enabling aircraft to stay aloft a little longer should problems arise on the ground (e.g. a blocked runway) and thus avoiding a complex and polluting diversion.

And let’s again not forget again that ‘tankering’ is used by most forms of transport including buses and trains, even private cars. So, here’s another question then. Does the excess fuel consumed by aeroplanes carrying more fuel than is needed just for their next journey produce more – or less – pollution than all the road vehicles such as buses - or trains - engaging in similar practices? The Aviation Oracle does not have a definitive answer this question either, but there are certainly millions (maybe even hundreds of millions) more road journeys made with excess fuel than there are airline flights doing the same. If campaigners are going to lobby against tankering, surely they should lobby against all forms and not just pick on aviation. Maybe aviation should become better at countering the arguments.

Above - Refuelling at Bangkok (Jaraphat)

All this talk about airlines saving money manifests itself in greater return on investment from airlines – leading to more manageable ticket prices. Outlawing or restricting tankering would inevitably therefore have an adverse impact on air fares, which would have to rise to cover the additional expenditure on more expensive fuel as well as lower aircraft productivity. Environmental campaigners of course welcome increases in the cost of flying, as they believe it will discourage air travel and ultimately reduce the number of flights and the pollution they produce.

The Aviation Oracle believes that post-Brexit Britain is going to need air travel more than ever, and the industry has already done a great deal to reduce emissions through the introduction of more efficient and less-polluting aircraft. The nub of the problem is that air travel is – and will, however it is taxed – continue to grow. Potentially more damaging than tankering is all the airborne holding that takes place when aircraft cannot land because of airfield congestion. Average holding times for aircraft inbound to Heathrow amount to 6.5 minutes, accounting for tens of thousands of tons of excess fuel being burned and even more pollution in the atmosphere.

A third runway at Heathrow – if managed correctly and not allowed to be solely used to accommodate traffic growth – would alleviate all of that holding and do far more to improve the environment than banning tankering. Its an inconvenient truth for the campaigners who are trying their best to curtail air travel rather than enable it to continue to support the global economy in a manner that is as least damaging as possible. Maybe the real need then is for the airline industry to be more vocal about what it is already doing and what might be the best means of combating increasing emissions, rather than cower down every time the BBC produce an adversarial TV programme. Furthermore, if the climate change lobby wins the argument over tankering, it might then turn its attention to trying to reduce the normal excess fuel reserves every flight carries for safety - how would we feel about those margins being reduced?

So tankering: cost saving, time saving, safety enhancing, fare reducing, a logistical necessity AND a minor impact on the environment (but in all likelihood having less than similar procedures in more prevalent forms of transport). We can all make a judgement on whether it is right or wrong innthe airline business, but on balance The Aviation Oracle believes its benefits outweigh the down side.

© The Aviation Oracle 2019

So you want to start an airline will be available soon; watch out for details on KJM Today.

The Aviation Oracle's point about Heathrow's third runway is also covered in Kevan James' book Heathrow Airport 70 Years and Counting, available now. Details on the Home Page under the Home Page Opinion.

bottom of page