Limitations or issues when flying below launch point

[midwestsherpa]

Curious if anyone has had experience flying below launch point; wondering how the Mavic 2 pro sensors react to a couple scenarios:
1. If the drone was to launch on the top of a sheer 1000 foot cliff; then navigated out over the expanse; how does that impact flight settings; ie max 400 ft ceiling etc. Does it recalibrate to the 1000ft height it now senses or does it retain the launch point as 'ground zero'? Any other issues I may not be thinking of? Would the drone be able to down into the expanse w/o issues? Are there certain settings that should be used in this scenario?
2. are there issues to be aware of when flying over very clear water in terms of depth sensory? wondering if it has trouble picking up the water level vs a lake bottom (as an example).

thanks

 

[Meta4]

Does it recalibrate to the 1000ft height it now senses or does it retain the launch point as 'ground zero'?

Your drone has no way to sense that the ground is 1000 ft below.
It makes no difference to flying the drone, whether it's 10 feet above the ground or 10,000 feet.
Where you launch from is always your home point and zero height.

2. are there issues to be aware of when flying over very clear water in terms of depth sensory? wondering if it has trouble picking up the water level vs a lake bottom (as an example).

Your manual has a list of situations that can be difficult for the downward facing sensors. Water is included in the list.
But you have to be within VPS range (<10 metres) for the sensors to see anything.

 

[Rockowe]

I constantly fly 95% of my flights below takeoff Point-... as I live at the Peak-
Measurements are Measured Negatively

All sensors operate as Normal - with reference to the Drone Position and Obstacles -

The Drone prefers Line of site for the RC - So the drone Must be able to see home - from its own Point of Reference-

RTH - will climb to (say) 30m above takeoff height - ...

Ie if you fly at Minus (-) 100 - if you RTH then it will first climb 130m before commencing the Home Run -
This is often a waste of Battery

Hope this helps

 

[pmshop]

Only drawback is you have to know where the "new floor" is.
Case in point, I did a boat spotting/ tracking on manual.
My take off point was about 50ft above the water.
When i started getting closer to the boat by lowering, I realized this and that I had not taken that into consideration.
Only flew at -10ft but didn't risk any further.

 

[Pegasusboysa42]

I fly off sea cliffs and mountain tops a lot. It just gives you a negative reading. It can be scary because u have no idea where “ground” actually is. It’s the worst over the ocean because I wonder if sensors will pick up the water and wave heights change. When flying off a sea cliff I’ve never had the courage to see if sensors will sense water. But over lakes ponds and pools my Mavic Air picks up the water.

 

[TheWolfen]

I fly off sea cliffs and mountain tops a lot. It just gives you a negative reading. It can be scary because u have no idea where “ground” actually is. It’s the worst over the ocean because I wonder if sensors will pick up the water and wave heights change. When flying off a sea cliff I’ve never had the courage to see if sensors will sense water. But over lakes ponds and pools my Mavic Air picks up the water.

As I understand it, they will see the water but not necessarily accurately, plus the water can vary in height as well if you are dealing with waves and swells. It can be risky to fly less than 10 feet above anything other than dead calm water. That's about as close as I've gotten and had no issues.

 

[Pegasusboysa42]

As I understand it, they will see the water but not necessarily accurately, plus the water can vary in height as well if you are dealing with waves and swells. It can be risky to fly less than 10 feet above anything other than dead calm water. That's about as close as I've gotten and had no issues.

This is about as close as I’ve gotten. This is before I had filters.

 

[tcope]

Search feature will show that there have been many posts with answers to these questions:

Search results for query: fly below take off point

mavicpilots.com

 

[johnmeyer]

I live on a ridge, so all my flights from my backyard are below me. The only issue I've had is that the Waypoint and other automated flight modes won't let you edit (DJI GO 4) waypoints with a negative altitude. I posted about this a month ago.

 

[LenSavage]

I live on a ridge, so all my flights from my backyard are below me. The only issue I've had is that the Waypoint and other automated flight modes won't let you edit (DJI GO 4) waypoints with a negative altitude. I posted about this a month ago.

I fly waypoints missions below takeoff point regularly with the Litchi app because I was unable to do so with Go4.
Another big plus is that with Litchi Mission Hub on your home computer, you can build missions, save them, then open them with the Mavic in the field and even sharer missions with other members of your team or whoever you choose.
Another plus with Litchi is it does a great job of gimbal tilt to the POI. This mission was built at home and I flew it with the Mavic and my old Phantom 3 4K. Notice that the controller is at my side - its all waypoints controlled:

I shoot this project in Beverly Hills every week or two - the pass at 1:15 is part of a waypoints mission that is below the home / takeoff point on the high road above the construction:

 

[midwestsherpa]

thank you all very much for your input and real life examples. There is so much that can be done with the drone that is just so amazing. Great videos! I have noticed that there is a reading on the controller screen that is measuring the distance to what is below it; I was flying over rocks and then a lake that was pretty clear. the readings above the rocks were pretty constant but once it got over the water it bounced around quite a bit making it a bit nerve racking. I agree on the ocean footage, very risky given the fluctuations. Many of your answers created more questions in my mind but I need to do some reading before I take any more of your time. My sincere thanks for your comments and examples.

 

[LenSavage]

Okay - one more; perhaps the simplest rule is - if you are down near the water level, you can more easily see the safe altitude. Just keep a bit of sky between the water and the drone.
I did some shots near the water in this one - some that are perhaps right up to the edge of 'a safe distance' but I got away with it: