Maximum Altitude Reached?

[selliott]

Hey Guys. Yesterday I lifted my Mavic 2 Pro off to try and capture photos of an amazing waterfall. It was in a forested area and I was standing on the edge of a precipice. So to get my shot I needed to lift off, then fly down about 30 feet. All went ok until I tried to land. My Mavic flew back ok...no return to home needed. But it would not ascend the final 3 feet to land and I was getting Max Alt reached warnings. It ended up being hooked by a small sapling and I was able to retrieve it. Any advice on where I went wrong?

 

[slup]

Yep ... my guess is that this was due to that you lost GPS coverage down there & the VPS sensors got a reading of something further down & zeroed the altitude ... & from there up to your landing spot it was over those 16ft mentioned in the user manual.

 

[selliott]

IF I had turned off downward vision do you think I would have avoided my tree landing?

 

[slup]

Nope ... not in your case, as the AC was without GPS, the set HP height was lost in the moment anything was sensed by the VPS sensors. From there those 16ft was counted ... wouldn't matter if you turn off the VPS by then.

Have seen cases like this before ... my only advice is, don't go down below your HP if it's a risk to lose GPS coverage.

 

[selliott]

Thanks for the advice! I think next time I'll just climb down to ground level for my shot. I guess I need to get in better shape! Have a great weekend!

 

[test2000Anafi]

I use Parrot Anafi so this could never happen to me, however, on DJI ATTI mode does not use GPS, correct?

Or would ATTI mode not allow you to fly beyond 5-30m?

never mind, I just read that ATTI mode restricts the height.

In that case, if such a thing happens again, try and find the drone to a spot where it does have GPS coverage, or get to a reachable landing point for retrieval

 

[slup]

I use Parrot Anafi so this could never happen to me, however, on DJI ATTI mode does not use GPS, correct?

Or would ATTI mode not allow you to fly beyond 5-30m?

Usually you have GPS coverage with the desired quality so the flight controller think's the position can be trusted ... that's GPS mode.

If without GPS coverage the VPS sensor on the belly can step in & lock on to the ground pattern & in that way stabilize the craft horizontally. That require enough light, a good pattern to lock on to, that the surface isn't reflective & the craft isn't too high up outside the coverage of the sensor ... that's OPTI mode

When both above fail ... the only thing that remains is ATTI. It's not actually a "mode"... it's a lack of means to assist with horizontal stabilization. In ATTI the craft have height hold, but no horizontal hold... meaning that the craft will drift with what's effecting it (wind for instance), it will not break when the sticks is released either. The craft is still under pilot control but if untrained in ATTI it can lead to that the pilot becomes surprised, start to give maximum stick inputs & think's the craft have started to flyaway... usually ends with a crash.

 

[selliott]

Thanks for all the input folks. I love it when posting in a forum ends up in a discussion that really sheds light and we all learn from each other. Have a great safe weekend everyone!

 

[tlswift58]

Thanks for all the input folks. I love it when posting in a forum ends up in a discussion that really sheds light and we all learn from each other. Have a great safe weekend everyone!

I do a lot of waterfalls (Western NC, Upstate SC, and N. GA) and the areas you fly in can be very non GPS friendly. That then restricts the drone to a max 98 ft altitude from take off. Typically I run into this a lot - so I find a nice opening in the tree cover and fly up to the max altitude of 98 ft. Let it sit for a couple of minutes and it "usually" can lock on enough satellites to then allow you to fly higher / further. Flying in a "bowl" type are WILL block most GPS signals enough to restrict to the 98 foot.

I have flown in gorges from high up - dropping probably 200-300 feet down - so a minus altitude on the screen. Yet, the gorge was wide enough to keep GPS signals to fly out. It is sketchy when you're flying below altitude and trying to keep VLOS and watch the camera at the same time.

Yet, in all my times - never had happen with what happened to you. When things do go awry - we all tend to panic and that is your worst enemy. My thoughts on it would be in future if you're doing this - bring the drone up as high as it will go out in a good clear spot and let it hover for a minute or two to see if it can lock on to GPS again. You can look in the upper right corner of your screen to the GPS icon and if it is RED - then you don't have enough GPS signal. Again, get it high as it will go in a clear area and let it hover and hopefully you'll regain GPS.

Last, but not least - don't wait till you get the low battery warning or the landing warning due to low battery to try the hover mode. Too late possibly by then.