Drone failed to RTH when signal lost

Dangerousdriver77 · May 24, 2020

This evening I took my Mavic Air 2 for a flight. I performed all pre flight checks including battery voltage, props compass and IMU and took off with no issues. The home point was updated and I had good GPS lock and signal from the RC to the drone. I flew the drone away from me and then got a loss of signal warning. I immediately pressed the RTH, and the controller began beeping however I had lost all video transmission and could not ascertain if the drone was going to RTH or not. I drove closer to the drone and finally the video signal returned, but strangely the drone had landed in a street on the pavement! I was able to take off and return to my location with no issues. No warnings were present, but this concerned me that the fail safe RTH did not work nor did my press of the RTH button. Can anyone please help me to understand why this would have happened?

DavidT_ NZ · May 24, 2020

Dangerousdriver77 said:
This evening I took my Mavic Air 2 for a flight. I performed all pre flight checks including battery voltage, props compass and IMU and took off with no issues. The home point was updated and I had good GPS lock and signal from the RC to the drone. I flew the drone away from me and then got a loss of signal warning. I immediately pressed the RTH, and the controller began beeping however I had lost all video transmission and could not ascertain if the drone was going to RTH or not. I drove closer to the drone and finally the video signal returned, but strangely the drone had landed in a street on the pavement! I was able to take off and return to my location with no issues. No warnings were present, but this concerned me that the fail safe RTH did not work nor did my press of the RTH button. Can anyone please help me to understand why this would have happened?

Did your phone battery on the RC have a good charge level? Are you in a congested signal area? Have you preset the RC to one frequency or left it on “auto”? Did you leave the drone hovering at around 20 feet at home for about 10 seconds before departure?

InvisibleName · May 24, 2020

Have you checked the settings for what it should do on loss of signal? Are you sure it’s set to RTH?
The options under Advanced Safety Settings (Remember that you can only check this when connected to your MA2) for when Signal Lost are:

Return to Home
Descend
Hover

If it was set to 2, and the RTH hadn’t been correctly requested by your actions, I believe it would have descend and, when it’s happy that the ground below is safe, it will land.

Meta4 · May 24, 2020

Dangerousdriver77 said:
this concerned me that the fail safe RTH did not work nor did my press of the RTH button. Can anyone please help me to understand why this would have happened?

Did you press the RTH icon or the autoland icon?
RTH is much more reliable than many drone flyers are.
I'd suggest going to a large, open area, flying the drone 100 feet away and experimenting with RTH to learn what it does and haow it does it.
Also practise cancelling RTH and resuming control.
And try switching the controller off to see what happens then.

Dangerousdriver77 · May 25, 2020

DavidT_ NZ said:
Did your phone battery on the RC have a good charge level? Are you in a congested signal area? Have you preset the RC to one frequency or left it on “auto”? Did you leave the drone hovering at around 20 feet at home for about 10 seconds before departure?

Hi David,

Yes the phone was at 99% charge, set to flight mode. I was in a congested area which I understand will affect the signal and range. What I do not understand is why the drone did to initiate the Smart RTH when the drone and controller lost signal.

I had let the drone hover over 29ft after the Home Point had been set.

Meta4 · May 25, 2020

Dangerousdriver77 said:
What I do not understand is why the drone did to initiate the Smart RTH when the drone and controller lost signal.

Since the interesting part of the flight happened after losing signal, there will be no recorded data to show what happened.
But if you post the flight data, that can confirm whether the Loss of Signal action was still set to the default (RTH) or not.
There might be some other clues in there?

InvisibleName · May 25, 2020

DavidT_ NZ said:
When you say “flight mode” do you mean Aeroplane Mode on the phone? I think the mobile phone has to stay in its normal operating mode so that its GPS and signal comms are clear. Not sure on that but worth checking. And did you try flying the drone in reverse, to get it back to you? Your earlier posting suggested that you only lost forward travel. Cheers.

Sorry, but you are wrong - the phones GPS & signal are irrelevant to the operation of the drone, and most users switch their phone to airplane mode to ensure that no calls come in to distract you and to reduce the chances of the phones WiFi etc interfering with the RC to drone connection.

InvisibleName · May 25, 2020

Dangerousdriver77 said:
Hi David,

Yes the phone was at 99% charge, set to flight mode. I was in a congested area which I understand will affect the signal and range. What I do not understand is why the drone did to initiate the Smart RTH when the drone and controller lost signal.

I had let the drone hover over 29ft after the Home Point had been set.

Did you check the settings for action on event of signal loss that I suggested At response #3?

sar104 · May 25, 2020

Dangerousdriver77 said:
Hi David,

Yes the phone was at 99% charge, set to flight mode. I was in a congested area which I understand will affect the signal and range. What I do not understand is why the drone did to initiate the Smart RTH when the drone and controller lost signal.

I had let the drone hover over 29ft after the Home Point had been set.

You still haven't confirmed what you have the failsafe action set to. Is it RTH, hover or land?

~Jb · May 25, 2020

I had this same thing happen to me although my outcome was better (thankfully). Let me preface by saying my situation was 100% my fault. I let the thought of flying my new drone completely overtake my common sense in checking all my settings before flying.

Basically, during the very first flight of my new MA2, everything started off normal, took off, home point set, and went off flying over a large mostly empty park. After some exploring and playing with a few quick shots, I decide to go look at a construction site nearby, this is where I messed up (I didn't know it yet) and I got complacent. Looking back now, I was so taken back by how nice the MA2 was flying and with all the youtube range tests at the back of my mind, I completely ignored the icons on the screen that were probably indicating that my signal was degrading. I kept carelessly flying, then boom, complete signal loss.

At the moment was completely shell shocked and in a panic, as I quickly started gathering my things, I knew that if the MA2 held its position, or landed it would likely be fine as it would be in a cornfield, but my immediate panicked thought was 'flyaway'. The remote seemed slow to respond, although seconds probably felt like minutes, then the screen went red and said "Emergency RTH in Progress". At first, there was nothing happening, now I realize that was the MA2 going to my set 200' RTH altitude, then as it slowly made it's way back to me. The connection flickered in and out but slowly came back online. I let the drone and the controller do its thing and soon the drone was back directly above me and safely landed within inches of where it took off.

Gut-wrenching and terrifying lesson learned. It's easy to let a shiny new toy cloud your judgment, happens to the best, but if you quickly run through your settings as part of your pre-flight checks, fly within your means, and definitely keep in eye on the information that the app is displaying, you have a much lower risk if anything bad happening, and then even if it does, a better chance that the built-in emergency safeguards will do what they are supposed to and bring your bird home.

apeel · May 25, 2020

Assuming you hit the RTH button on the remote, and not the Auto Land icon on the screen. Is that true?

Here's another thought, since you lost signal, it would have automatically initiated a RTH (assuming that is how your settings were set for Loss of Signal. Shortly after that, you said you hit the RTH button. Could it be that in the short time period, it actually regained signal and then when you hit RTH it effectively cancelled the RTH? Just wondering?

InvisibleName · May 25, 2020

apeel said:
Assuming you hit the RTH button on the remote, and not the Auto Land icon on the screen. Is that true?

Here's another thought, since you lost signal, it would have automatically initiated a RTH (assuming that is how your settings were set for Loss of Signal. Shortly after that, you said you hit the RTH button. Could it be that in the short time period, it actually regained signal and then when you hit RTH it effectively cancelled the RTH? Just wondering?

That’s why his flight log has been requested...

DavidT_ NZ · May 25, 2020

InvisibleName said:
Sorry, but you are wrong - the phones GPS & signal are irrelevant to the operation of the drone, and most users switch their phone to airplane mode to ensure that no calls come in to distract you and to reduce the chances of the phones WiFi etc interfering with the RC to drone connection.

I have seen a posting where a user was on a moving boat and they updated the RTH position at the RC. How can that occur if the phone is in Aeroplane Mode? Is the mobile not disconnected from external signalling, when in that safety state? Or does the RC take over the positioning for DJI Fly?

InvisibleName · May 25, 2020

DavidT_ NZ said:
I have seen a posting where a user was on a moving boat and they updated the RTH position at the RC. How can that occur if the phone is in Aeroplane Mode? Is the mobile not disconnected from external signalling, when in that safety state? Or does the RC take over the positioning for DJI Fly?

The Mavic Air nor the MA2 do not have Dynamic Home Point, which is what you are describing. When you reset the Home point, it is calculated based on the current location of the drone, not the RC.

Meta4 · May 25, 2020

DavidT_ NZ said:
I have seen a posting where a user was on a moving boat and they updated the RTH position at the RC. How can that occur if the phone is in Aeroplane Mode?
Is the mobile not disconnected from external signalling, when in that safety state? Or does the RC take over the positioning for DJI Fly?

Flight mode just switches off wifi/bluetooth and the cell phone communications, but GPS being a receiver only keeps running and passes on location data via cable if the operator chooses to reset the home position.
None of this is at all relevant to the OP's situation since RTH works when all signal from the controller is lost.
It does not depend on GPS or anything else from the controller.

Dangerousdriver77 · May 26, 2020

InvisibleName said:
Did you check the settings for action on event of signal loss that I suggested At response #3?

Yes mate, checked it and it was set to descend and not RTH. So that solves that! I was just lucky that I managed to retrieve the drone when it landed.

AMRE2ME2 · May 27, 2020

Very good. Glad you figured it out. My suggestion is to test every setting, like RTH, so you know exactly what to expect. These drones do exactly what we tell them to do. Even if your settings aren’t what you think they are.

MarginalizedWhackJob · May 30, 2020

Dangerousdriver77 said:
Yes mate, checked it and it was set to descend and not RTH. So that solves that! I was just lucky that I managed to retrieve the drone when it landed.

I have an original Phantom 4 high upon a hoodoo in Utah at 10k feet because I lost signal and it was set to HOVER rather than RTH. A very expensive lesson (and a stern dressing down from the "Director of Finance")