Aethos: advancing aircraft recycling

When we speak, he has just finished a marathon training session. I’ve just come from the gym. We both laugh briefly as we adjust before the call starts. It feels fitting. The conversation that follows is about the same thing: momentum, and what it means to keep moving.

The question that started it all

The question itself goes back to his time at Delft University of Technology, where he studied aerospace engineering. Originally, his interest was in space. “Rockets, planets, Star Trek,” he says. But during his studies, his focus shifted towards the organisational side of aviation, towards processes, people, and the systems behind it. At the same time, he wanted to contribute to sustainability. That combination led him to a simple but fundamental question for his master’s thesis: what happens to aircraft once they stop flying? Then, at YES!Delft, he turned that question into a business.

Building a business from end-of-life aircraft

With AELS, Derk-Jan built a business model around disassembling and dismantling aircraft in a way that extends the lifecycle of parts of those aircraft. After acquiring aircraft, valuable spare components are sold to keep other aircraft operational. In contrast, other sections are repurposed in more creative ways, from flight simulators to design objects. What remains is recycled. “People often don’t realise how much of an aircraft can still be used,” he says.

People often don’t realise how much of an aircraft can still be used” – Derk-Jan van Heerden

That model exists largely because of how aircraft ownership and end-of-life decisions are structured. “About half of all aircraft aren’t owned by airlines,” he explains. “They belong to leasing companies, but in the end, both lessors and airlines can decide to stop operating an aircraft.” When that moment comes, the aircraft enters a new phase. It can be sold to another operator who continues flying it, or to a party that will take it apart. “Sustainability can play a role in that decision,” he says, “but it’s usually weighed against financial outcomes.” While recycling is always part of the process to some extent, higher-quality recycling often comes at a cost, and decisions are therefore frequently driven by what delivers the highest return. That gap is exactly where AELS operates.

Growth, milestones and momentum

Along the way, there were clear milestones, such as buying the first aircraft, and working on specific types he had set as personal goals. “I remember wanting to work on a Boeing 747,” he says. Later, acquiring a Boeing 777 for the first time marked another moment of progress. At the same time, those milestones rarely felt like endpoints. “I thought briefly: we did it,” he says. “But then the real work starts, and I was already busy with the next steps.”

When everything changes

Around the time the company reached a strong financial position, his life changed abruptly. Derk-Jan was diagnosed with a brain tumor, and doctors initially expected that he only had a few months left to live. He decided to step away from the company and sell his shares, both to spend time with friends and family and to ensure the company could continue without him.

That timeline, however, luckily did not unfold as expected.

A different kind of impact

Today, Derk-Jan is still very much alive and currently training for the Rotterdam Marathon in 2026. He speaks about it matter-of-factly. It might take a while before he leaves this world, so he wants to use his time and resources in a meaningful way, while also enjoying life. “I can’t do nothing,” he says. “Maybe I learned that at YES!Delft, maybe it’s just who I am.”

That mindset led to the creation of Aethos, a foundation focused on improving aircraft recycling. Where reuse within aviation is already relatively well developed, recycling still presents significant challenges. Materials have become more complex, regulations have become stricter, and volumes have remained relatively small. “Aluminium is still manageable,” he explains. “But carbon fibre is much harder.”

Through AETHOS, he funds research projects to address these challenges. One example focuses on improving aluminium recycling in aircraft structures, where different alloys are closely coupled. If those materials can be separated more effectively, it would enable higher-quality recycling rather than downcycling.

At the same time, he is realistic about the nature of the work. Unlike a company, the foundation is not built around a profit model. “If it were profitable, it would already exist,” he says.

Lessons from building a company

When I ask what he’d want to share with founders, he goes back to his time at YES!Delft. There was this quote from his professor Sicco Santema, who says: “Fun makes it run.”

For Derk-Jan, that’s really what it comes down to. Building a company is a bit like running a marathon. It starts out fun, then it gets hard, and at some point, you just have to keep going if you want to make it to the finish.

Building a company is a bit like running a marathon. It starts out fun, then it gets hard, and at some point, you just have to keep going if you want to make it to the finish.” – Derk-Jan van Heerden

At the same time, he reflects on something he would approach differently. Each milestone quickly turned into the next task. “I was never very good at enjoying those moments” he says. His advice is simple: take the time to recognise your progress and celebrate the steps along the way. Even though it gets hard, like training for a marathon, take some time to enjoy reaching your goal.

Looking ahead

Through AETHOS, he now works with people who are trying to solve similar challenges, both within aviation and beyond. The focus is on improving how materials are recycled, but just as much on figuring out what actually works in practice.

“If you’re working on improving recycling, I’d love to talk,” he says.

The foundation is still growing, and are actively looking for partners and people who want to contribute, whether that’s through ideas, collaboration, or funding.

Derk-Jan van Heerden