Good morning,
On 12/31/16 I was flying my Phantom Pro 3 over some hunting land. Everything was going good until I brought it home. It was hovering over my position when all of a sudden it banked hard to the east and took off. I didn't have control of it at all. I hit the RTH button, but it didn't respond. I lost connection, jumped in my car, and went down the road hoping to regain a connection. I did briefly and it said critically low battery 3% landing, motor obstruction (most likely a tree) and then nothing.
The problem is that final location when I regained connection was not logged. I have no idea where it is and I'm at a loss. At its last known locatio according to my flight log, n it was 229 feet in the air moving east at a rapid pace. I'm trying to determine a search area as best I can, but I have no idea what to do. I was offered a 10% off replacement drone, but I want to know what caused the error and where the drone is. I did a firmware update the previous day. Prior to that I had no issues. If anyone can help me determine a search area based on its heading, and altitude, along with battery life is appreciate it. I've had a sick feeling in my stomach since 12/31/16 and I have had little support up to today. I'm hoping for some help.

Here's the link to my flight log. http://www.phantomhelp.com/LogViewer/W8J7T1RTRJDXSRCJDG0B/

Really sorry to hear about your loss.
Did you get in touch with our tech support at support@dji.com?
Our engineers will help to analyse the flight records for you and let you know what could have caused the issue.

This is a tricky flight record.
For the first 30 seconds you took it straight up to 270 feet and things seem normal but there is a gap in the record with no data until 15:50 with the battery at 18% and a Yaw Error that won't go away.
We can't tell what happened for more than 15 mins while the downlink was lost but the Phantom is only 300 feet away when the flight data resumes and moving erratically with the speed varying and seeming to have no relation to the stick inputs.
It's in Go-Home from 15:53 but continues to get further away despite the Home Point being unchanged.
From 16:06 it is in atti mode and although maintaining height around 250 ft, the speed is swinging from 0-54 mph.
From 15:57 on we see Speed Errors coming and going and the constant yaw error.
Data finishes at 16:51 at 13% battery and the Phantom 1640 feet away and going further at 230 feet high and over 50 mph.

A Yaw Error is like a compass error (only worse) and forces the Phantom to ignore GPS because it has a problem with conflicting data from the compass and GPS.
It can be caused by a hardware malfunction or a badly calibrated compass or launching from reinforced concrete surfaces.
Looking at where you launched,, my money would be on a malfunction.
Have you uploaded your flight data to DJI?
You do this by clicking the cloud icon in the flight record section of the app.
Then contact DJI's online chat and tell them the story and see where it goes from there.

I wouldn't like to guess where it ended up.
It's running low of battery when the record ends but it's acting crazy and probably ended up somewhere further east.
After over two months outdoors and probably crash damage, it's probably not worth recovering.

Thank you for the thoughtful response. I have uploaded the flight record to DJI, but I haven't gotten any support. They just told me my warranty expired in September so they won't help me with any information. The data analysts refuse to review the errors or offer any insight into where it went or what happened. They said they would give me a 10% discount for a replacement. I've been very frustrated with the lack of support. I just want to know what happened and they give me nothing. The drone was great before that flight. I literally had no issues at all up until that flight and it just took off on me. I calibrated the compass before the flight, had 18-20 satellites throughout the flight, and it just started acting crazy and took off. I am at a loss to be honest and so frustrated with the lack of support from DJI I cannot wait for other companies to catch up with them and their technology so I don't have to deal with them anymore.

    It sounds like you definitely had some kind of malfunction, and I'm sorry for your loss.  

    When did you upload your logs to DJI? I would definitely be interested in what their response is to your situation.