Scary one this evening!!

[A.O.]

So end of the day and I'm going to fly, get my stuff and a couple batteries and out the back door I go. Normally my first flight I make my rounds around my property, wood, fields, ponds, whatever I kind of cruise around at altitude normally in that 150 foot range so I'm above everything and check things out. Well I'm getting better at this guy so from that 150 ish loot level I go screaming down into my back field, get to about 65 feet and BANG I lose ALL signal! I get the warning in my goggles of a "critical failure" RTH or something like that and my goggles go blank! What the heck??? At first I get nothing at all in the goggles, then it comes back for a moment says something about hover and goes blank again. Now the screen is not really blank but there are no values listed anywhere all just lines. So I remember I've been flying IN the woods and have my RTH set to hover so I try to change that... nope, not while it is in RTH mode I cant even access "advanced safety ". I click on "find my drone" and it brings up the last 10-15 seconds of video I was shooting and shows me right where it should be sitting.. hovering! Now I'm kind of in that panic mode at this point and I know the battery is going to be getting low and I hope it truly is sitting there! Dang... I grab my stuff and start the jog out to where it should be because without any signal I have no picture!!! No real clue if its sitting there or anything!! Holy incriminating evidence Batman, YES I am flying BVLOS!! Get over it will ya! Its all on my property! So I get maybe 3/4 of the way out there and I regain signa!! Woopie!! I cancel RTH , reset the RTH to go to home point and almost immediately it goes into Battery Low RTH! Up up and away it goes and off to home, I wait till it gets close to its landing spot I shut off RTH and land it in the grass in my back yard!! YAY!!
So I throw the next battery in it and go to do the exact same thing but this time knowing what might happen, and having RTH set to actually come home if it does. Now this is a field I fly in all the time BUT from a different location, I normally fly from my sniper tower out in the same field, straight line and VLOS to that end of the field. Anyway, I do the same thing, go screaming down into the field from altitude and once again lose all signal (make mental note of such) this time it climbs to 132 ft altitude for RTH at which time it gets signal as it climbs above the tree line! I thought I would just let it run its course and RTH which it did with no problem.
So I'm guessing if it loses all signal with the remote and goggles the birds GPS is what brings it to the home point.. good lesson learned!

 

[GateFather]

So end of the day and I'm going to fly, get my stuff and a couple batteries and out the back door I go. Normally my first flight I make my rounds around my property, wood, fields, ponds, whatever I kind of cruise around at altitude normally in that 150 foot range so I'm above everything and check things out. Well I'm getting better at this guy so from that 150 ish loot level I go screaming down into my back field, get to about 65 feet and BANG I lose ALL signal! I get the warning in my goggles of a "critical failure" RTH or something like that and my goggles go blank! What the heck??? At first I get nothing at all in the goggles, then it comes back for a moment says something about hover and goes blank again. Now the screen is not really blank but there are no values listed anywhere all just lines. So I remember I've been flying IN the woods and have my RTH set to hover so I try to change that... nope, not while it is in RTH mode I cant even access "advanced safety ". I click on "find my drone" and it brings up the last 10-15 seconds of video I was shooting and shows me right where it should be sitting.. hovering! Now I'm kind of in that panic mode at this point and I know the battery is going to be getting low and I hope it truly is sitting there! Dang... I grab my stuff and start the jog out to where it should be because without any signal I have no picture!!! No real clue if its sitting there or anything!! Holy incriminating evidence Batman, YES I am flying BVLOS!! Get over it will ya! Its all on my property! So I get maybe 3/4 of the way out there and I regain signa!! Woopie!! I cancel RTH , reset the RTH to go to home point and almost immediately it goes into Battery Low RTH! Up up and away it goes and off to home, I wait till it gets close to its landing spot I shut off RTH and land it in the grass in my back yard!! YAY!!
So I throw the next battery in it and go to do the exact same thing but this time knowing what might happen, and having RTH set to actually come home if it does. Now this is a field I fly in all the time BUT from a different location, I normally fly from my sniper tower out in the same field, straight line and VLOS to that end of the field. Anyway, I do the same thing, go screaming down into the field from altitude and once again lose all signal (make mental note of such) this time it climbs to 132 ft altitude for RTH at which time it gets signal as it climbs above the tree line! I thought I would just let it run its course and RTH which it did with no problem.
So I'm guessing if it loses all signal with the remote and goggles the birds GPS is what brings it to the home point.. good lesson learned!

I had something similar happen flying near my house. I went maybe 1000 feet across some trees and as soon as i dipped below the tree line in a field, i lost signal and saw RTH. I had my RTH set to 328 or something. When it regained signal in my goggles it was way up there heading back towards me. Very cool feature, but definitely think there is a disconnect between the videos we see online and real life signal. Maybe being new to FPV, I'm just not yet aware of what to do and not to do in terms of keeping signal. It really seems like it needs a pretty clear line of sight with the goggles. But then I see videos of experienced pilots flying through buildings and car garages from the parking lot, so I still really don't get it.

 

[JoostGT3]

Funny you guys mention it; last weekend I was happily flying along when I noticed the distance and altitude numbers in the goggles weren’t changing. Flew around for a bit but realized that the goggles graphical overlay had frozen. Videofeed worked just fine, but the information displayed had frozen. Flew around for a bit more to see if it would come back but it didn’t. Landed it with only 5% of battery, so the RTH hadn’t kicked in either! Scary stuff, and it pays to be very vigilant!

 

[A.O.]

I had something similar happen flying near my house. I went maybe 1000 feet across some trees and as soon as i dipped below the tree line in a field, i lost signal and saw RTH. I had my RTH set to 328 or something. When it regained signal in my goggles it was way up there heading back towards me. Very cool feature, but definitely think there is a disconnect between the videos we see online and real life signal. Maybe being new to FPV, I'm just not yet aware of what to do and not to do in terms of keeping signal. It really seems like it needs a pretty clear line of sight with the goggles. But then I see videos of experienced pilots flying through buildings and car garages from the parking lot, so I still really don't get it.

Here are my thoughts, and just that... my thoughts. It was explained to me that all the water/moisture in the trees was a big signal block. Those guys flying through buildings and such are probably right out side and close, some of those buildings have big holes in the walls, windows, doors whatever so the signal is still pretty strong. Where I lost signal was about 1/2 mile away and mostly woods between the bird and I so LOTS to block the signal. Sounds like you ere doing about the same.. long distance and thick woods between you and your bird.

 

[A.O.]

Funny you guys mention it; last weekend I was happily flying along when I noticed the distance and altitude numbers in the goggles weren’t changing. Flew around for a bit but realized that the goggles graphical overlay had frozen. Videofeed worked just fine, but the information displayed had frozen. Flew around for a bit more to see if it would come back but it didn’t. Landed it with only 5% of battery, so the RTH hadn’t kicked in either! Scary stuff, and it pays to be very vigilant!

Well now my video feed disappeared completely, nothing at all, and my graphics just showed blank lines kind of like at start up. Interesting your RTH didn't kick in, mine does at 20-25% maybe.

 

[rktman]

Here are my thoughts, and just that... my thoughts. It was explained to me that all the water/moisture in the trees was a big signal block.

BINGO! Water is about one of the most effective EM blockers, only metal being better.

If you already know that submarines can't use radio while under water, now you know why. Microwaves only penetrate centimeters before being completely absorbed.

Dense foliage between you and straight line to your drone will block the swignal as effectively as if you were under water.

ALWAYS leave your RTH settings to return to the homepoint, and set a relatively high return altitude (I use 250ft). You want your drone back if you lose contact, don't you? I lost signal twice a few days ago in the same situation -- descending to take a closer look at something. In this case it was simply the fact that I was close to a mile away, and when I dropped below 100 ft, there was a whole lotta dirt between my RC and the aircraft.

Hover in place will never return the signal, or your drone to you. Good way to lose it. I DO use this option (done it once, so far) if I'm doing some FPV through spaces where there is overhead obstruction (trees). Don't want it to ascend in that situation.

I've never had a "real" catastrophic RTH, where a drone came back and landed while I never got control of it again when RTH started. In years past, some people DID experience things like this because of bugs in the DJI GO4 app.

 

[rktman]

Those guys flying through buildings and such are probably right out side and close, some of those buildings have big holes in the walls, windows, doors whatever so the signal is still pretty strong. Where I lost signal was about 1/2 mile away and mostly woods between the bird and I so LOTS to block the signal. Sounds like you ere doing about the same.. long distance and thick woods between you and your bird.

No, typical building materials do not block HF EM signals (a little attenuation, but not much). This is why your phone can still get a GPX lock in your house, most one story buildings, and some multistory buildings on the ground floor.

However, in the woods, you will lose GPS as soon as you don't have a clear view of the sky. Note that your drone can lose GPS in the woods too, switching to VPS for positioning capability. As such, if you've been tooling around the woods for a bit from half a mile away and then lose signal, the goggles may not even have a very accurate position on where it was when signal was lost.

 

[rktman]

Funny you guys mention it; last weekend I was happily flying along when I noticed the distance and altitude numbers in the goggles weren’t changing. Flew around for a bit but realized that the goggles graphical overlay had frozen. Videofeed worked just fine, but the information displayed had frozen. Flew around for a bit more to see if it would come back but it didn’t. Landed it with only 5% of battery, so the RTH hadn’t kicked in either! Scary stuff, and it pays to be very vigilant!

This happened to me twice. Bug in the goggles, DJI is aware of it and will fix it in a future (hopefully next) firmware release.

It happens if you have an SD card in the goggles, and it gets full, or is corrupted in some way and can't be accessed by the goggles. You won't get any warning, just stop getting telemetry.

My situation was a little different -- I have a full SD card inserted (forgot it was there), wasn't using it, but telemetry froze after losing and then regaining signal from the drone.

 

[rktman]

Guys, carefully read the entire RTH section of the user manual. RTH is not only a low battery feature.

 

[A.O.]

ALWAYS leave your RTH settings to return to the homepoint, and set a relatively high return altitude (I use 250ft). You want your drone back if you lose contact, don't you? I lost signal twice a few days ago in the same situation -- descending to take a closer look at something. In this case it was simply the fact that I was close to a mile away, and when I dropped below 100 ft, there was a whole lotta dirt between my RC and the aircraft.

I fly IN the woods a lot and not over them which is why I had it set to hover. When I'm flying under the canopy I don't want it RTH ing up into the canopy so I set it to hover.

Watch this, at about the 1:25 mark I got a battery RTH warning and it tried to RTH up through the canopy, I finally got it under control and back down... and the hightailed it out of the woods.

 

[JoostGT3]

This happened to me twice. Bug in the goggles, DJI is aware of it and will fix it in a future (hopefully next) firmware release.

It happens if you have an SD card in the goggles, and it gets full, or is corrupted in some way and can't be accessed by the goggles. You won't get any warning, just stop getting telemetry.

My situation was a little different -- I have a full SD card inserted (forgot it was there), wasn't using it, but telemetry froze after losing and then regaining signal from the drone.

Except that I have never had an SD card in the goggles. And the one that is in my drone wasn’t full at the time it happened. I’m not too fussed about it yet, but it shouldn’t happen too often! Just gotta get used to checking the battery level a bit more often.

 

[rktman]

Yeah, RTH hover is correct if you're flying with overhead obstructions.

In that case, you gotta be ready to hoof it closer to the drone to regain control.

 

[A.O.]

Yeah, RTH hover is correct if you're flying with overhead obstructions.

In that case, you gotta be ready to hoof it closer to the drone to regain control.

Yep, which is exactly what I did.

 

[Noobnoobnoob]

So end of the day and I'm going to fly, get my stuff and a couple batteries and out the back door I go. Normally my first flight I make my rounds around my property, wood, fields, ponds, whatever I kind of cruise around at altitude normally in that 150 foot range so I'm above everything and check things out. Well I'm getting better at this guy so from that 150 ish loot level I go screaming down into my back field, get to about 65 feet and BANG I lose ALL signal! I get the warning in my goggles of a "critical failure" RTH or something like that and my goggles go blank! What the heck??? At first I get nothing at all in the goggles, then it comes back for a moment says something about hover and goes blank again. Now the screen is not really blank but there are no values listed anywhere all just lines. So I remember I've been flying IN the woods and have my RTH set to hover so I try to change that... nope, not while it is in RTH mode I cant even access "advanced safety ". I click on "find my drone" and it brings up the last 10-15 seconds of video I was shooting and shows me right where it should be sitting.. hovering! Now I'm kind of in that panic mode at this point and I know the battery is going to be getting low and I hope it truly is sitting there! Dang... I grab my stuff and start the jog out to where it should be because without any signal I have no picture!!! No real clue if its sitting there or anything!! Holy incriminating evidence Batman, YES I am flying BVLOS!! Get over it will ya! Its all on my property! So I get maybe 3/4 of the way out there and I regain signa!! Woopie!! I cancel RTH , reset the RTH to go to home point and almost immediately it goes into Battery Low RTH! Up up and away it goes and off to home, I wait till it gets close to its landing spot I shut off RTH and land it in the grass in my back yard!! YAY!!
So I throw the next battery in it and go to do the exact same thing but this time knowing what might happen, and having RTH set to actually come home if it does. Now this is a field I fly in all the time BUT from a different location, I normally fly from my sniper tower out in the same field, straight line and VLOS to that end of the field. Anyway, I do the same thing, go screaming down into the field from altitude and once again lose all signal (make mental note of such) this time it climbs to 132 ft altitude for RTH at which time it gets signal as it climbs above the tree line! I thought I would just let it run its course and RTH which it did with no problem.
So I'm guessing if it loses all signal with the remote and goggles the birds GPS is what brings it to the home point.. good lesson learned!

All's well that ends well. What signal strength are you using. since your woods seem to be on the thick side, you might want to crank it, if you haven't already?

 

[A.O.]

All's well that ends well. What signal strength are you using. since your woods seem to be on the thick side, you might want to crank it, if you haven't already?

Hmmm, I run it at whatever it came with, its adjustable? How so, and where should I run it?

 

[Noobnoobnoob]

We'll, I might be wrong about that, my V1 goggles with Air and Vista units has in settings a easy to increase transmission level, however it seems that within the fpv drone it is not available, I'll have to look further into this as it really doesn't make sense to me, but then again it is DJI, they love to do things that make no sense.

 

[Tomk_]

I believe that the the DJI FPV transmits at 40mhz and is not adjustable.

 

[Florent]

I also had a scary RTH experience when I had set up my altitude to 100m.
my mistake was that I had not clearly defined my limits in terms of visual range. At some point during the flight I dived down and lost contact suddenly. The goggle video went all black and the only thing o was able to witness was the drone suddenly shaking as I saw it turn to home point. It was strange to see that big H letter over a black background and no possibility to regain control.
so the drone seems to be doing his thing until the video comes back all of a sudden and the screen in filled with a concrete wall and windows!
The drone was going straight home at 100m but there was a building in the middle. Lucky the sensors had detected it but the drone did not climb.
at that point I realized I might have my control back, cancelled RTH and climbed until I was over the building.
from now on, RTH is set at 200m!

- would the drone have continued to go straight even with an obstacle in front?
- will DJI include in future updates the track back feature of the Mavic?
- why is the video recording disabled after a signal loss? I have no footage of that near miss because of that.

 

[rktman]

I'd like to see them add the trace back route RTH feature like on the mavic pro 2.

 

[rktman]

I've had half a dozen episodes now of loss of control signal while still having video. its always very nerve wracking!!