Interesting experiment. I did not expect the result.

[AVLJMA]

I brought my Mavic Air 2 to my home state of Wisconsin from NC. I visited a friend who is a farmer as was the last three generations of his family. His farm connects with his brother's farm which connects with his father's farm. They grow corn and raise dairy cattle.

So I took the opportunity to experiment with my Mavic Air 2. I launched from my friend's home and flew across his fields and then I continued across his brother's field and approached his father's home. My RC starting going from white connection bars to amber connection bars.

I then touched the screen with the return to home. As usual, TWO options came up. LAND and RETURN TO HOME. The drone was at 320 ft and hovering above a wide open yard at his father's farm. Instead of pushing RETURN TO HOME. I pushed LAND. We pre-planned the event and decided to drive over to recover the drone.

So I pushed LAND and the drone dropped slowly. A video at his father's home watched as the drone slowly decended...until it hit about 15 feet above ground level. It then suddenly went into RTH home mode. Lifted off to 300 feet and returned to my friend's farm.

We changed out batteries and tried again. The drone/remote control went to amber as we reached his father's farm. AGAIN, I chose LAND and NOT the option to RTH. The drone slowly decended and, again, at about the 10 to 15 foot mark went into RTH mode. I could not force it to land because the signal was lost. It ignored the command to LAND and went into RTH mode.

I was both surprised and relieved that the drone would act like that. I'll have to attach the video of the attempted land tomorrow.

 

[MAvic_South_Oz]

I could not force it to land because the signal was lost. It ignored the command to LAND and went into RTH mode.

Probably was failsafe RTH that kicked in when it got too low for signal.
But of course you'd think it would land as originally commanded, seems odd that it would have the option if it wouldn't go through with the operation.

You know what will almost certainly tell you ?
Your flight log.

Section 3, phantomhelp one is easy, get the report and post up the link here for some analysis.

Mavic Flight Log Retrieval and Analysis Guide

With the introduction of the Mavic Mini there has been a noticeable uptick in the number of posts requesting help with lost or crashed aircraft. While there is plenty of help and advice available on this forum, and detailed guidance and options on several other websites, I thought that perhaps a...

mavicpilots.com

 

[Meta4]

I was both surprised and relieved that the drone would act like that. I'll have to attach the video of the attempted land tomorrow.

Unless you changed the default Loss of Signal action (RTH) to land or hover, on losing signal, you can expect the drone to do exactly as it's programmed and RTH.

If the drone had maintained signal, it would have landed, but dipping below trees and losing signal, makes it follow whichever option you have selected for Loss of Signal.

 

[AVLJMA]

Unless you changed the default Loss of Signal action (RTH) to land or hover, on losing signal, you can expect the drone to do exactly as it's programmed and RTH.

If the drone had maintained signal, it would have landed, but dipping below trees and losing signal, makes it follow whichever option you have selected for Loss of Signal.

I completely forgot that. Of course you are right. Thanks.

 

[Zbip57]

I pushed LAND and the drone dropped slowly. A video at his father's home watched as the drone slowly descended...until it hit about 15 feet above ground level. It then suddenly went into RTH home mode. Lifted off to 300 feet and returned to my friend's farm.

I did a series of experiments on that a couple of years ago and posted four videos demonstrating this behaviour over on the DJI forum. See:
Auto-Land aborts and reverts to RTH when control signal lost.

The issue at the time was that the Mini originally had no option to change the default Failsafe procedure upon loss of control signal. At first on the original Mini the only Failsafe response was RTH.

The DJI Fly app was subsequently updated in v1.0.8, modified to include three options for Loss of Signal;

• Return-to-Home
• Descend, or
• Hover.

Now, if you want to ensure the drone will continue to land at your chosen remote landing site, even if control signal is lost on the way down, you first need to switch your Loss of Signal response to Descend.

There's still the potential issue of "Landing Protection" deciding it doesn't approve of the look of your remote landing spot. The Mini may stop its descent and hover just short of landing, asking for your confirmation that you really do want to land there. But if you've already lost control signal you'd never see that message nor be able to send confirmation to land. In that case it would just hover there until the battery runs out.

 

[offtheback]

Unless you changed the default Loss of Signal action (RTH) to land or hover, on losing signal, you can expect the drone to do exactly as it's programmed and RTH.

If the drone had maintained signal, it would have landed, but dipping below trees and losing signal, makes it follow whichever option you have selected for Loss of Signal.

Am I correct that your answer is an example of

Occam's razor?​

 

[slup]

... stop its descent and hover just short of landing, asking for your confirmation that you really do want to land there. But if you've already lost control signal you'd never see that message nor be able to send confirmation to land. In that case it would just hover there until the battery runs out.

No ... it will most probably stay hovering until the low battery RTH count down (10 sec) starts & as you can't cancel it due to being disconnected ... it will again go for a RTH.

 

[Zbip57]

No ... it will most probably stay hovering until the low battery RTH count down (10 sec) starts & as you can't cancel it due to being disconnected ... it will again go for a RTH.

I worried about that too, and even wrote exactly that in an earlier post somewhere.

But then somebody else replied that they had tested it, and it actually does land at low battery rather than doing a RTH. They said it's easy enough to test for yourself. But I never tried it.

It's something that needs confirmation for sure. The only problem is you need to select an "unsuitable" landing location to trigger the landing protection system. That will prevent it from actually landing, leaving it to hover there until a low battery condition either triggers RTH, or a critically low battery causes a forced landing in that spot.

If it does choose to RTH, then that rather defeats the entire intent of this objective.

But if you fall asleep while waiting for the battery to run out and it suddenly does go into a forced landing, you need to react quickly to prevent it actually dropping into that "unsuitable" landing location. That's why I was reluctant to try the test myself.

 

[Zbip57]

Am I just imagining this, or was there at one time an option to disable "landing protection"? That would have been an easy solution for this issue.

I just checked my DJI Fly app with the Mini and can't find that option anywhere.

 

[Big Nate]

Am I just imagining this, or was there at one time an option to disable "landing protection"? That would have been an easy solution for this issue.

I just checked my DJI Fly app with the Mini and can't find that option anywhere.

I think you can turn landing protection off with the Litchi app.

 

[Baron von Richthofen]

There's still the potential issue of "Landing Protection" deciding it doesn't approve of the look of your remote landing spot. The Mini may stop its descent and hover just short of landing, asking for your confirmation that you really do want to land there. But if you've already lost control signal you'd never see that message nor be able to send confirmation to land. In that case it would just hover there until the battery runs out.

When my Air2 was forced to land due to loss of signal and low battery it was over a corn field. The downward pointing video recording showed that it moved slowly around at around ten feet searching for a safe spot to land. In the very broken signal I was by then receiving, I remember it reporting it didn't like the landing area. With just 1% remaining it finally found and put down in a small clearing in the corn. When it works it really works!