All sensors off drone rises and falls on its own

[WRJP]

We have a mavic pro at work and I have a new Mav 2 pro
theres a river with a waterfall with over hanging trees near by

with all sensors off so I can fly in a straight line without a sensor stopping or pushing
both drones drift up and down

at one stage hovering while I moved to get a better view the drone was slowly dropping just caught it
before it went into the water.

and flying say 2m off the top of the water it will all of a sudden start rising which ruins the shot

any ideas if there is another setting I can use to fly in small spaces without the drone rising and falling randomly on it own

 

[Not A Speck Of Cereal]

I see this in the manual on page 13: "The aircraft automatically changes to Attitude (ATTI) mode when the Vision systems are unavailable or disabled and when the GPS signal is week or the compass experiences interference. (See the manual -- there's more to that paragraph).

Even in P mode, you might be in ATTI mode (no GPS position lock) when you have all sensors turned off. In ATTI mode, your craft will drift with the wind. There's nothing random about it -- you either need to enable positioning and/or GPS, or learn to fly in ATTI. ATTI mode (as you discovered) requires eyes-on the craft at all times, especially when flying over water.

It sounds like, with what you're trying to do without sensors, you need to fly by stick.

I also see in the manual (same page), that Sport mode turns sensors on but still uses GPS -- you might try that. Note that in Sport mode, you need to be careful with speed in such tight spaces. I think this might mean first turning all sensors back on, then going into sport mode to have GPS without sensors.

Chris