Saving lives and making a side income with an emergency aircraft tracking app

Ernst Mulders, 33, has been building side projects since he was a teen. He always made products with monetization in mind, until the one time he didn’t.

He built emergency services tracker AirAssist four years ago as a way to improve his app skills. Now it’s his most successful project — and it’s saving lives.

He took me through his journey so far👇.

Always launching

I've been building on the side of my studies, and then my work, since I was about 16 years old.

I'm a very product-minded person and I just want to build everything that pops into my mind. I’m always launching things on Product Hunt or the App Store or Google Play.

When I was about 18, I made time-tracking software to keep note of my working hours. I was so surprised when it made money. But with the knowledge I have now, I know it could have been a way more successful product.

I also made a travel website called Seven Places that gave you examples of bars or restaurants with a similar vibe to the spot you were currently in.

It used Instagram to pull popular posts about a particular place, look at who posted them, and then gather information about other locations they’d posted about. It would do some algorithm stuff and suggest other similar places to visit.

Then Instagram killed my API key after a policy change. A bit of platform risk there.

A simple demo project

I always built products with their money-making potential in mind. AirAssist was the first time I didn’t think about it. I wanted to get to know React Native and I needed an idea to work on.

A friend of mine was interested in trauma helicopters here in the Netherlands. We have a public network that shares information about where ambulances need to go.

I made an app that displayed the location of four or five different helicopters every minute on this gray map. It was just a demo project for myself at this point and there was no monetization.

Drive growth with feedback

But users quickly found it and started asking for improvements. I’m now tracking over 550 different aircraft in real-time. You can set time zones and get notified when an aircraft will fly past you. 

I built out international versions. In the U.K., I have a big incident notification for if more than two aircraft respond to the same area. This isn’t public information there and can often beat news agencies.

I had a feedback form from the start. After a month or so I got this email from a hospital in the Netherlands. Professionals were using the app, which I hadn’t anticipated.

Building a freemium model

I realized then I needed to look at monetization. I started placing ads in the app, but I didn’t have that many users and it didn’t even cover my server cost.

So I introduced a one-off €2.99 option to remove ads. My wife and I both thought nobody would pay for it.

But that same day, people started buying it. After that, it made sense to put new features behind the premium option.

A year in, I thought, okay, I probably need to do something with subscriptions, because my costs are recurring. I upped the pricing to around a euro a month, €10 a year and €20 for the lifetime version.

It was scary at first, but people started paying straight away. Last May, I doubled the prices again and people are still paying.

App store optimization

I didn’t really do any marketing. People in the Netherlands search for the messaging network, which is called P2000. So I included it in the name of the original Dutch app. It was all App Store search optimization.

Launching in the U.K. and Germany is a lot harder because I don’t have a specific word people are searching for. In those countries, it grows more by word of mouth and people posting about it on social media.

I expand the app country by country. I'm looking at France and Austria. It's already in Switzerland and Luxembourg and Belgium. But it's hard to expand. You have to get a list of all the relevant helicopters. And when you launch you start out with zero users again.

Rinse and repeat

Waterbomber is basically the same thing, but for firefighting assets.

I got an email from someone in California who’d used AirAssist in the early days. He said, ‘Wouldn’t it be nice if we could track all the firefighting asses in the air?’

At the time, you had to look on Flight Radar or whatever, which is really hard to filter. The U.S.A is a bigger market, so I thought it could be interesting.

But it was a difficult challenge. I learnt the hard way just how many firefighting assets there are flying around. It’s a lot of stuff to track.

The app is now in Europe and Australia as well. It’s quite a chore to manually add every relevant aircraft.

Another daunting part is that, say in Canada, there are these vast areas where radar coverage is really bad. These firefighting aircraft also often fly very low to the ground. So, they appear on radar for like 20-30 minutes and then pop up somewhere completely different.

The app itself is fully React Native, built with the start components in there. Then my API is all PHP driven with some Node.js microservices lingering around.

On a weekly basis I spend say like 10 hours in the evenings and sometimes the weekends working on the apps. There's a lot of customer support in there and it takes more time than I initially anticipated.

Saving lives

I have a lot of professional users and they often reach out to me with feedback. I had a police officer contacted me to say the app saved his team a few minutes — and that helped save a person’s life.

Police often have to land a few miles away from a particular incident, then drive a doctor to the actual site. Normally they it takes time to get the right location from dispatch. My app can speed that process up.

I’ve had more messages like that, about AirAssist actually being used to save people’s lives. And that is incredible. It’s the most fulfilling part.

It was the same with Waterbomber.  Fire departments are actively using it. I get messages from departments in Italy and Australia and the U.S. telling me how they use it every day to be able to locate aircraft. I was so surprised, but it’s really, really cool.

Striking a balance

Ultimately, indie hacking my hobby and I enjoy it, so I can fit it in around work. If I had to choose between watching Netflix and working on the product, I’d choose the product every time.

The end goal is to eventually work on it full-time. But I’m happy with the balance I’ve struck right now.

Indie hacking is great because it’s still doable with a family. It’s doable with a nine to five.

Do the unexpected

I didn't expect AirAssist to take off. Sometimes it's the unexpected thing that works.

I’d also say to keep it simple. The first version of my app was so rubbish but people still really liked it and started using it. Don't over-engineer and don't wait too long to launch.

Listen to what your users say. Sometimes it's so obvious to you as a maker how stuff works. It turns out that users see stuff differently because they don't live with your app every day. Listen to them.

And don’t forget that the product is only a small part of what you’re doing. You need to monetize it and market it if it’s ever going to work.