The use of Sustainable Aviation Fuel (SAF)

Towards Greener Skies

Sustainability is one of the defining challenges of our time — and the aerial surveying sector is no exception. Every flight brings valuable data to society, but it also carries an environmental cost. How can we balance this responsibility while striving for innovation and efficiency?

To open this conversation, EAASI is launching a new series where members share their experiences, reflections, and initiatives on environmental good practices in aerial surveying.

The first contribution comes from Lars Najbjerg of Focus Aircraft, who reflects on the environmental impact of different aircraft types and explores practical ways to reduce emissions.

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Environmental Impact of Aerial Survey: The use of Sustainable Aviation Fuel (SAF)

Before we joined EAASI as observers, we were impressed to discover that the association had a code of ethics—including a specific clause on environmental impact: "Members will keep the environmental impact as small as possible."

This is a noble and necessary goal, but I think we can all agree that it is also a challenging one. Aerial surveys, by their very nature, involve the use of aircraft that burn fossil fuels, and thus an environmental impact is inevitable.

Hopefully, the environmental cost is offset by the value of the survey data provided—but are we truly doing enough to keep that impact as small as possible?

Many companies in the industry still operate older piston aircraft burning Avgas. Others use turboprops that run on Jet A1, while a smaller number fly light twins with modern engines capable of operating on Mogas. When we look solely at the types of fuel used by these aircraft, some clear conclusions emerge:

• Avgas (100LL) is the most widely used fuel in survey aircraft. Unfortunately, it is also the most environmentally harmful due to its lead content, which poses health and ecological risks. It emits approximately 2.95 kg CO₂ per liter.
  

• Jet A1 is less toxic in terms of its chemical composition but emits slightly more CO₂ at around 3.29 kg CO₂ per liter.
  

• Mogas, though used the least, is the least toxic and emits about 2.90 kg CO₂ per liter.

  
  

Using Mogas would seem to be the best way to keep the environmental impact as small as possible, but since only certain engines run on Mogas, it comes with other challenges.

An Alternative: SAF

There is, however, an alternative to these traditional fuels: Sustainable Aviation Fuel (SAF).

SAF is a renewable or waste-derived substitute for conventional Jet A1. It is designed to reduce the overall carbon footprint without requiring modifications to aircraft engines. SAF can be produced from used cooking oil, agricultural waste, municipal solid waste, algae, or even CO₂ captured from the atmosphere.

While SAF emits a similar amount of CO₂ when burned, its net emissions—factoring in the full lifecycle—are significantly lower, approximately 0.95 kg CO₂ per liter.

Since SAF can only be used in place of Jet A1, we can conclude that Jet A1 (when replaced by SAF) is theoretically the most environmentally friendly option per liter used. But how does this hold up in practice?

Comparing Three Aircraft

Let’s compare three representative aircraft categories:

• Airplane 1: Twin-engine piston (Avgas)

• Airplane 2: Single-engine turboprop (running on SAF)

• Airplane 3: Light twin piston (Mogas-capable)

Aircraft	Speed (KTAS)	Fuel Flow (L/hr)	Fuel per NM (L)	Fuel Type	CO₂ per NM (kg)
Airplane 1	170	120	0.74	Avgas	2.17
Airplane 2	150	140	0.93	SAF	0.89
Airplane 3	125	34	0.27	Mogas	0.78

Airplane 3 emits the least CO₂ per NM, thanks to its efficient use of Mogas. Interestingly, Airplane 2, when running on SAF, has only slightly higher emissions than Airplane 3. Airplane 1, on the other hand, shows the highest emissions by a significant margin.

(Note: Those interested in the detailed aircraft models behind this comparison are welcome to contact Lars Najbjerg, Focus Aircraft, directly.)

Procuring SAF: The Book and Claim System

Obtaining SAF can be difficult due to its limited availability at many airports. However, solutions like the Book and Claim system—offered by various suppliers—make it feasible.

Here’s how it works:

1. The operator uses conventional Jet A1 at their operating airport.

2. They request to "offset" their fuel usage (partially or fully) with SAF.

3. An equivalent volume of SAF is injected into the fuel supply chain at another location.

4. The environmental benefit is credited to the operator.
   

Operators receive a Declaration of Environmental Attributes, which documents the emission reduction and allows them to track their emissions.

This system lets operators reduce their carbon footprint without needing physical SAF delivery at every airport—making it a practical solution under current infrastructure constraints.

Analysis

The comparison suggests that:

• Light twin Mogas-capable aircraft can achieve the lowest CO₂ emissions per nautical mile.

• Turboprops paired with SAF (via Book and Claim) offer a compelling balance of reduced emissions and operational flexibility.

• Twin-engine Avgas aircraft are the least sustainable option, due to lead emissions and higher CO₂ output.
  

Of course, other operational factors must also be considered—such as payload capacity, maintenance costs, and fuel availability. However, single-engine turboprops often prove a better and cheaper alternative operationally, with longer maintenance intervals and the availability of Jet A1, which can reduce ferry flights significantly (further lowering emissions).

Conclusion

To truly align with the association’s code of ethics, the industry should consider ways to reduce reliance on older Avgas-burning aircraft. For smaller operations, Mogas-capable aircraft are a good solution. For larger platforms, increased SAF adoption—via systems like Book and Claim—should be encouraged.

In addition, operational efficiencies such as optimized flight routes and maintenance planning can reduce unnecessary ferry flights and overall emissions.

By combining smarter fuel choices, modern aircraft technologies, and innovative fuel procurement strategies, the aerial survey industry can more effectively uphold its commitment to minimizing environmental impact—while continuing to deliver the valuable data society relies on.

Example of Certificate

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This article was written by Lars Najbjerg, Focus Aircraft. The views expressed are those of the author and are intended to contribute to the debate on environmental practices in aerial surveying. EAASI invites other members to share their perspectives, so that together we can highlight solutions and good practices for reducing the industry’s environmental footprint.