Yesterday I experimented with the Spark tracking me on my bike.

As I have an iPhone holder on my bike and the Spark would by in close proximity to me while tracking, I didn't feel the need to use the RC. Would be clumsy to attach to my handlebar. So I paired the Spark with my iPhone, positioned the Spark on my side, enabled active tracking and draw a rectangle around me and the bike. To my surprise, the Spark confirmed my selection with a small icon of a bicycle. Wow, Spark does actually know, it should track a bicycle.   

So I started cycling and Spark flew at my side.
Increased speed and I heard the motors of the Spark gearing up as well. The Spark was able to keep up with my speed.
I was really impressed ...

but after a few seconds the sound of the motors changed abruptly. Spark hovered in place, the front lights had changed from green to red.

The iPhone told me the reason: Spark hat reached its maximum flight distance. Guess what, the hardcoded maximum distance of 100 m when you fly with Wifi.

I was aware of this limit: Max. 50m height and 100m distance. And I'm fine with it, because that is about the max. transmission distance you get via Wifi.

But I didn't expect to hit this limit, when the Spark is tracking me (and my iPhone) at probably 3m distance.

I think, this behaviour is not ideal. The Spark should limit the range in Wifi mode from the actual position of the phone and not from the home point. And it should not return to the original home point on low battery, when it is already close to the phone and instead just hover.

I know, it is possible to track not only yourselfs but someone else and in that case the range limit cannot be set to the person you are tracking. But I didn't ask to set the range limit to the tracking person but to the position of the controlling phone. If you track yourself, the homepoint would be moving with you, if you track someone else and don't move yourself, homepoint would be stationary.

So for know, in case you want to track someone/something that moves faster than just walking, you should use the RC or tracking stops after a few seconds. And you should land the Spark before the battery runs low and the Spark enters RTH or you have to react quickly to get out your RC to stop RTH and land the Spark at your current location.

@DJI you should rethink this behaviour.

Actually there should really be an option to set the spark to "autorefresh HP to phone every 30 sec. if phone is in GPS Mode and user is confirming these option before start tracking".
This way, it would cover the 100m in phone mode thing, but also the RTH in RC mode

This is really bad.... I figured it some time ago.
What you can do to overcome a bit is to take off 100m ahead of you, fly back to you, then start Active Track. It will fly 200m (the first 100m, reaching the “ground zero”) then another 100m.

You can also, manually, set HomePoint to phone´s location. (each 100m)