So I almost crashed the Mavic Air in the stream today.  
Everything looked fine, no warnings and then the mavic air got some hickup.  Had I not reacted and pulled up the drone I think it would have crashed.  As i pulled up the drone higher it kept drifting to the left almost hitting the trees.  After a while tough it stabilized.
Any Idea to what could have caused this issue.  Im now worried to fly over water especially at low altitude should this happens again.

https://www.youtube.com/watch?v=p-nlFHwIR5w&feature=youtu.be

Flying low over water or reflective surfaces can be a problem, it is explained in your manual, sensors will have problems with the movement of the water or as in this case the moving ice.

It would be recommended to fly above VPs range when Flying over water, although we see many having no problem we must always be aware, good job recovering.

Wow close call.  Very good recovery.  Yeah water/reflective surfaces and and will throw off the sensors so always be prepared for this.  

Nice recovery.
Did you check the flight data to see if it recorded any errors or warnings?

Hi, I'm sorry for that case happened. Glad to know that the drone recovered, it's really lucky. Could you please check if there is an error message on your DJI GO4 APP? Thanks!

Lucky you saved the Air, very good recovery. I always fly around 15 meters or higher when going over water.

This video is a great demonstration of the height problems the drones have flying over water.



My guess: remember it is trying to look at the surface of the water for patterns to hover, the water you were flying over had recognisable chunks of ice that MOVED! When those moved the drone thought it was moving and tried to compensate hence the wild sideways movements.

Good recovery

Good you recovered.
Did you check the flight logs?
Maybe some sensor errors

You could switch off VPS sensors in the settings when flying over water

That was close do you know what happened

That was close - good recovery though