"RTH fly backwards for 50 m on its original flight route" straight flight or actual path?

[Faster]

That does not answer my question. If you watch the video he demonstrates fail safe, but since he flew straight out, when the fail safe kicked in, it's not clear weather that 50m is retracing it's steps or just doing a straight shot because the path it was on was also a straight shot. Plus the Air 2s is more sophisticated with precision landing, cant assume it's the same.

When Fail Safe is activated the drone will fly BACKWARDS FOR 50 meters ON IT'S ORIGINAL FLIGHT ROUTE. It won't go to the Home Point, or to the left/right or any other direction, it will fly exactly backwards in the same route it has before being disconnected, looking for connection because it used to have it when it was flying before over that path, also note that won't be any obstacles interfering because it flew through that route before. If the drone is unable to connect again during those 50m flying backwards in the same original route, it will ascend and will fly in straight line to the Home point at the altitude you selected in the RTH settings menu.

 

[mobilehomer]

Think this way, if it had RC connection and lost it, 50 meters back along the same path SHOULD restore it. If not, then it goes into FS rth.

 

[Skyryder]

Did you see the suggestion in post 6?

Yes, but I was hoping someone actually could just give a straight anser as it's cold and windy outside, not going to be flying for a month probably.

 

[Skyryder]

OK, got it, thanks guys. I guess "original flight path" it is. I was just concerned if it would take a shortcut since that would be the most direct route back home.

 

[Meta4]

OK, got it, thanks guys. I guess "original flight path" it is. I was just concerned if it would take a shortcut since that would be the most direct route back home.

It's not about getting home ... it's about getting back to where it had good signal.

 

[ReproRetro]

So hypothetically, if I flew behind a tall building, lost signal, and maybe only 20m away, it's smart enough to not just backup straight into the building? Will it actually retrace it's exact path around the building before it ascends into RTH?

It won't retrace the path unless you have flown in a single straight line.
When you issue an RTH the drone locates the last recorded home point and then heads straight for that.
If it's not in Sport mode, and obstacle avoidance hasn't been switched off, then (theoretically) it will avoid the building, unless the battery is low.
But in your settings, make sure you set the RTH height to more that the tallest buildings

 

[Faster]

It won't retrace the path unless you have flown in a single straight line.
When you issue an RTH the drone locates the last recorded home point and then heads straight for that.
If it's not in Sport mode, and obstacle avoidance hasn't been switched off, then (theoretically) it will avoid the building, unless the battery is low.
But in your settings, make sure you set the RTH height to more that the tallest buildings

The drone will retrace whatever path it flown before. The question was not about RTH but when the drone losses connection and Fail Safe is kicked on. This issue has been explained extensively in this thread.

 

[Roamer105]

It looks like all the bases have been covered in the answers and the Failsafe section of the manuals explain the process in detail.
What was your question?

Mini 2
Failsafe RTH
If the Home Point was successfully recorded and the compass is functioning normally, Failsafe RTH automatically activates after the remote controller signal is lost for more than 11 seconds.
When the firmware is updated to v1.1.0.0 and above, the aircraft will fly backwards for 50 m on its original flight route and ascend to the preset RTH altitude to enter Straight Line RTH.
The aircraft enters Straight Line RTH if the remote controller signal is restored during Failsafe RTH.
When the aircraft flies backwards along the original flight path and the distance from the Home Point is less than 20 m, the aircraft stops flying backward on the original flight route and enters Straight Line RTH at the current altitude.

Air 2S
Failsafe RTH
If the Home Point was successfully recorded and the compass is functioning normally, Failsafe RTH automatically activates after the remote controller signal is lost for more than 6 seconds.
The aircraft will fly backwards for 50 m on its original flight route, and then enter Straight Line RTH.
If the aircraft is less than 50 m from the Home Point when the video signal is lost, it flies to the Home Point at the current altitude.

I went out to test this with my A2S flying a curvy pattern including changing elevation along the path while recording video and then turned off the RC. It did what it written in the manual BUT IT DOES NOT FLY BACKWARDS it actually turns around 180 degrees in place and flies FORWARD BACK on the original path including elevation changes, then after the 50 meters it starts the actual RTH with precision landing at the end.

 

[Faster]

I went out to test this with my A2S flying a curvy pattern including changing elevation along the path while recording video and then turned off the RC. It did what it written in the manual BUT IT DOES NOT FLY BACKWARDS it actually turns around 180 degrees in place and flies FORWARD BACK on the original path including elevation changes, then after the 50 meters it starts the actual RTH with precision landing at the end.

I had the same experience. When I tested with my Air 2S, the drone did the same thing, it rotated 180 degrees and flew forward back to the same path it was flying before connection was lost.

 

[Meta4]

BUT IT DOES NOT FLY BACKWARDS it actually turns around 180 degrees in place and flies FORWARD BACK on the original path

Backwards/Back ... the difference is subtle.
It's just a minor translation issue.
Not uncommon in DJI manuals

 

[Skyryder]

I went out to test this with my A2S flying a curvy pattern including changing elevation along the path while recording video and then turned off the RC. It did what it written in the manual BUT IT DOES NOT FLY BACKWARDS it actually turns around 180 degrees in place and flies FORWARD BACK on the original path including elevation changes, then after the 50 meters it starts the actual RTH with precision landing at the end.

Wow, that's a surprise. Thanks for testing that out. I guess it makes sense to have the camera facing the direction it's flying in. Smarter little drone than I thought.

 

[Roamer105]

Wow, that's a surprise. Thanks for testing that out. I guess it makes sense to have the camera facing the direction it's flying in. Smarter little drone than I thought.

Yes flying forward especially for the A2s is much safer since it uses 4 cameras.

 

[Roamer105]

There is a question that I have yet to find an answer to and I a not about to test for it:
RTH with "bypassing obstacles" is using APAS logic and frankly the worst nightmare I think would be not using APAS and instead just hover until the battery dies. This may happen where connection can not be re-established in time and landing would be terrible. So I always enable "bypassing" for RTH. However, APAS is unavailable when recording video at 5.4K! So, in that case, what exactly happens when I record 5.4K and end up losing connection with possibly an RTH altitude set too low!!

 

[Faster]

There is a question that I have yet to find an answer to and I a not about to test for it:
RTH with "bypassing obstacles" is using APAS logic and frankly the worst nightmare I think would be not using APAS and instead just hover until the battery dies. This may happen where connection can not be re-established in time and landing would be terrible. So I always enable "bypassing" for RTH. However, APAS is unavailable when recording video at 5.4K! So, in that case, what exactly happens when I record 5.4K and end up losing connection with possibly an RTH altitude set too low!!

RTH would run according to the settings you input before flying independently of any video settings the drone had. Is VERY IMPORTANT to set RTH altitude higher than any object, structure or tree near your flight zone. Not all drones have obstacle avoidance and for sure will crash in to any object interfering its path.

 

[Roamer105]

RTH would run according to the settings you input before flying independently of any video settings the drone had. Is VERY IMPORTANT to set RTH altitude higher than any object, structure or tree near your flight zone. Not all drones have obstacle avoidance and for sure will crash in to any object interfering its path.

I agree about setting a sufficiently high RTH altitude. However, sometimes one underestimates and I had a situation where I flew behind a rocky mesa and lost all comms. The A2s did exactly as designed, it backed off, but that was not sufficient to regain connectivity, then started its failsafe RTH which would make it collide with that rocky mesa as the altitude I had set was just shy of the top of the mesa. Once again, the A2s did what it was supposed to do, it recognized the obstacle and increased the elevation to overcome it and returned home safely. I eventually got comms back and took over. But at that time, I had my video set to 4K and I also had APAS enabled.

 

[Faster]

I agree about setting a sufficiently high RTH altitude. However, sometimes one underestimates and I had a situation where I flew behind a rocky mesa and lost all comms. The A2s did exactly as designed, it backed off, but that was not sufficient to regain connectivity, then started its failsafe RTH which would make it collide with that rocky mesa as the altitude I had set was just shy of the top of the mesa. Once again, the A2s did what it was supposed to do, it recognized the obstacle and increased the elevation to overcome it and returned home safely. I eventually got comms back and took over. But at that time, I had my video set to 4K and I also had APAS enabled.

You were lucky your drone had obstacle avoidance. Another drone like a Mini would've collided with that rocky mesa.

 

[FafaZoli]

Hi Guys,

Most probably my Mini2 crashed into a rock after losing RC connection.
I made a mistake, that I did not calculate the height of the rock accurately and just set 100m as RTH ALT.
I could not find my mini2 since it crashed to the rock and most probably fall into a valley in the jungle.

However I checked the flight data, and it seems to me that the drone did not try to retrace the original path for 50m and immediately started the straigh line RTH.

My log is here:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Can you please one expert check it and give opinion what could went wrong?

Thank you in advance.

 

[Meta4]

Hi Guys,

Most probably my Mini2 crashed into a rock after losing RC connection.
I made a mistake, that I did not calculate the height of the rock accurately and just set 100m as RTH ALT.
I could not find my mini2 since it crashed to the rock and most probably fall into a valley in the jungle.

However I checked the flight data, and it seems to me that the drone did not try to retrace the original path for 50m and immediately started the straigh line RTH.

Your drone was on the verge of losing signal for the last 40 seconds of the recorded flight data.
You lost signal when you flew behind a small hill marked with the yellow arrow.
The yelow line shows the RTH path.

At the time that the recorded flight data ends, the drone was 538 ft higher than the launch point.
That puts it about 100 ft above the ground below it at the time.
The RTH path would have flown across the high ground marked with the yellow arrows.
From 400 ft to 700 ft on the RTH path,the ground level would have been approx 50 ft below the drone's RTH height.
But if there were any trees 50 ft or higher, the drone may have run into them.

 

[FafaZoli]

Your drone was on the verge of losing signal for the last 40 seconds of the recorded flight data.
You lost signal when you flew behind a small hill marked with the yellow arrow.
The yelow line shows the RTH path.

At the time that the recorded flight data ends, the drone was 538 ft higher than the launch point.
That puts it about 100 ft above the ground below it at the time.
The RTH path would have flown across the high ground marked with the yellow arrows.
From 400 ft to 700 ft on the RTH path,the ground level would have been approx 50 ft below the drone's RTH height.
But if there were any trees 50 ft or higher, the drone may have run into them.

Thank you very much for your valuable analysis.
However the manual of the Mini2 says that if failsafe kicks in, the drone will fly back 50m in the original route.
I assume it did not happen, the drone started to return to home along the shortest way (straightline).

Do you have any idea why it wont fly back a bit before straighline RTH?
Did I do something wrong (expect too low RTH altitude set)?
I would like to learn from it to avoid such kind of things in the future.

Thank you in advance for your advice and help!

 

[Meta4]

Thank you very much for your valuable analysis.
However the manual of the Mini2 says that if failsafe kicks in, the drone will fly back 50m in the original route.
I assume it did not happen, the drone started to return to home along the shortest way (straightline).
Do you have any idea why it wont fly back a bit before straighline RTH?

Here is the relevant section of the manual:
The aircraft will fly backwards for 50 m on its original flight route and ascend to the preset RTH altitude to enter Straight Line RTH.
The aircraft enters Straight Line RTH if the remote controller signal is restored during Failsafe RTH.

The second sentence explains why your drone did not fly 50 metres before entering straight line RTH.
The drone regained signal 10 seconds after signal was lost at 5:54.1 and on regaining signal, the drone entered straight line RTH.

Did I do something wrong (expect too low RTH altitude set)?

We can't be sure.
If the hill had no trees or just small trees, the drone should have cleared it and the battery level was good for the return flight.
But if there were trees 50 ft or higher, that might be the problem.
But without data to show what happened after signal was lost, we can only guess.