RTH activates, plenty of battery, app glitch shows, readings strange, lands in lake..

[Meta4]

Oh boy...

Looking at the flight data, I see two problems.
The big one is that you appear to have let RTH do the driving.
RTH is very good at navigating but it's a slow driver.
From 9:04 at 62% and 16900 feet out until 17:27 at 12% and 1920 feet out, you relaxed in the back seat and let RTH cruise at a lazy 20mph.
RTH will do 20 mph if let to drive and 20 mph is not the most efficient speed for distance.
You can drive at 35 mph which is just a tiny bit less efficient than your max efficiency speed which is around 31 mph.
The battery was running down while the Phantom wasn't getting anywhere fast.
It would have made it home if you kicked the right stick forward or cancelled RTH and drove yourself.

Second issue is the final course you chose when you did attempt to get to shore.
If you went toward the closest land, you might have just made it.

Mistakes are a good way to learn and you can get a lot of experience from them.

 

[Joe Dodaro]

Looking at the flight data, I see two problems.
The big one is that you appear to have let RTH do the driving.
RTH is very good at navigating but it's a slow driver.
From 9:04 at 62% and 16900 feet out until 17:27 at 12% and 1920 feet out, you relaxed in the back seat and let RTH cruise at a lazy 20mph.
RTH will do 20 mph if let to drive and 20 mph is not the most efficient speed for distance.
You can drive at 35 mph which is just a tiny bit less efficient than your max efficiency speed which is around 31 mph.
The battery was running down while the Phantom wasn't getting anywhere fast.
It would have made it home if you kicked the right stick forward or cancelled RTH and drove yourself.

Second issue is the final course you chose when you did attempt to get to shore.
If you went toward the closest land, you might have just made it.

Mistakes are a good way to learn and you can get a lot of experience from them.

Thanks for the analysis. It's actually great to hear some things that didn't come up with tech support.

The big one is that I was fighting with myself the whole time to push the throttle! I was thinking most efficient must be RTH Speed as that would just be most logical in my mind. Something that had just never came to mind previously. So when it was on its way back it gave me the RTH info that it wasn't going to make it.. It litterally pushed my thumbs off the throttle thinking "ok just leave it .. It'll kill the battery with any extra gas..."
Oh well.. Live and learn.. New bird in my possession .. Waiting for some calm winds.

 

[Meta4]

The big one is that I was fighting with myself the whole time to push the throttle! I was thinking most efficient must be RTH Speed as that would just be most logical in my mind.

Lets see ... 16900 feet = 3.2 miles
At 32 mph you would have been home in 6 minutes rather than dawdling along for 8.5 mins.
The lessons that cost are the most effective.
You'll be a better flyer with the new bird and that experience under your belt.