Precision Landing failure!

[Jacknet007]

Today I had a precision landing failure that I cannot explain.

I took off with 100% battery and 16 sats in GPS mode and selected precision landing. I have taken off from this very spot many times (pitchers mound on a baseball field) and have precision landed every time within inches.
Mavic takes off with a landing pad with pattern on it to create good contrast and pattern for landing precision.
Compass and IMU were checeked prior to flight and were normal.

Flew out for about 2 miles and hit RTH with 68% battery remaining. Cruised home and it initiated landing at about 260 ft altitude with 42% . Distance was 0.5 ft so GPS was accurate and at 17 sats. It did its normal landing mode descend and at about 55 feet the green "precision landing locating landing point" indicator came up the DJI Go 4 app. Suddenly, it veered to the left and went about 50 feet distance before I gave it right stick to stop where it was heading. Almost hit a baseball field outer fence. I was able to control and land. WTF?

Here is what I checked:
Cameras and sensors on bottom of Mavic were clean with no dirt.
Verified that takeoff went straight up with no stick inputs and got the "Home point has been updated" message.
No loss of GPS entire flight with minimum 15 sats
Same Landing pad with pattern been used many times and no ground changes after takeoff.
No stick inputs during descent.
Distance from home point was .6 feet and altitude about 55 feet when it started to veer off. While it was veering off it maintained its original takeoff heading.
No ambient lighting errors.
No recent app or firmware updates. Been on .900 since I initially updated it from .700 when I first got it over a month ago. Have done probably over 50 precision landings always within a foot at most.

I have seen this Mavic make slight adjustments during precision landing to line up with landing target but this is the first time I have seen it fly off like this. It clearly went beyond its GPS accuracy which has always been under 15 feet or so.

Any ideas?

 

[lisadoc]

It happens. The technology is not perfect. That's why you should always stand by ready to take manual control (like you did). Once is an incident. Twice is a problem. When you get to separate incidents, that's probably when it's time to take a look at the flight logs/data. You could dive in to it now, but it might not give you any answers.

 

[Ping^Spike]

Any ideas?

Do you have a flight log you could share?

 

[lisadoc]

Just do a search on this forum for "flight log". Plenty of folks have shared their logs for troubleshooting purposes. Look here to see how to retrieve your own logs:
How to retrieve a .DAT

 

[DavidMathew]

It happens. The technology is not perfect. That's why you should always stand by ready to take manual control (like you did). Once is an incident. Twice is a problem. When you get to separate incidents, that's probably when it's time to take a look at the flight logs/data. You could dive into it now, but it might not give you any answers.

Maybe you not choosing the right solution. If you are looking the same for commercial or interested to invest then for precise landing you can use FlytDock by FlytBase or if you are just looking for some hobby project or testing then you may try IR Lock. But both have different properties.