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Mavic 2 Pro - RTH Failure - Fly away - Lost
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JeremyMelbourne
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Hi Guys,

I wondered if anyone else has experienced this issue. Before I begin I want to say I have had 4 previous versions of the DJI Drone so I am famiiar with it.

I bought the new Mavic 2 Pro, flew it 3-4 times without issue.

On the third day of owning it I took it out on a coastal area of Vietnam.

I flew the drone up about 150M and towards the area I wanted to time lapse.

I lost video signal and I moved slightly and it recovered.

I lost video signal a second time, only this time it did not recover.

The remote controller then disconnected and no re-connection to the drone was established.

I pressed the RTH button a few times and waited. 25 minutes later. No drone.

Battery was full charge. Home point was set. GPS was strong signal with many satelites detexted. Compass calibrated. RTH height 150M. Above any obstacles.

Drone was in SPORT mode.

So I am of the impression that when the DJI Mavic 2 loses signal RTH may not workk properly - has anyone else had this issue?

DJI told me I flew it into a building. Completely untrue. Was no where near any buildings

Appreciate response from anyone else having similar issues.


2019-8-24
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JJB*
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Hi Jeremy,

without reading out a flightlog it is hard to give some comments.

cheers
JJB
2019-8-24
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DJI Stephen
DJI team
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Hello and good day Jeremy Melbourne. I am sorry for the trouble and to know what happened to your DJI Mavic 2 Pro. Since this issue happened on the said drone. I would recommend you contact our DJI support team to start up a ticket at https://www.dji.com/support?site=brandsite&from=nav for further assistance with regards to this matter. We have the professional team who would do their best to find out the reason of the incident and then the corresponding resolution would be provided. Thank for your understanding and for your support.
2019-8-24
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raven swe
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if the remote disconnected then pressing rth aint gonna do squat, might be a case of drone started to rth when signal lost and pressing rth cancelled it,
2019-8-24
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David Martin Graff
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That;s a tough break, I was flying the Mavic 2 Zoom today and disconnected at 20,100 feet and RTH worked as it came back almost 4 miles away. You need to know your flight path, make sure you are not in any obstructed areas, also was not flying in Sport Mode, and when I fly that far I usually try and stay in Position Mode..
2019-8-24
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Gimpy
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Without more information, we can only speculate. Since you mentioned that you were flying in a "coastal area", I'm guessing that the wind prevented your Mavic from returning, but that's all it is: a guess. To answer your question, there are no widespread reports of RTH problems, and failures to return have usually turned out to be pilot error.

It may be possible to provide more definitive information if you provide a flight log by uploading it to PhantomHelp using these instructions and then posting a link to the uploaded log into this thread.

2019-8-24
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Ahmed Hussain
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Sorry, are you sure about the option when the drone disconnected was set to RTH not hover?
2019-8-24
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djiuser_kF82lXmfhGAP
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Hee
Do you know how to save video in original 4K format from drone?
2019-8-24
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JeremyMelbourne
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Gimpy Posted at 8-24 08:47
Without more information, we can only speculate. Since you mentioned that you were flying in a "coastal area", I'm guessing that the wind prevented your Mavic from returning, but that's all it is: a guess. To answer your question, there are no widespread reports of RTH problems, and failures to return have usually turned out to be pilot error.

It may be possible to provide more definitive information if you provide a flight log by uploading it to PhantomHelp using these instructions and then posting a link to the uploaded log into this thread.

https://www.phantomhelp.com/LogViewer/7C6B36EX2OZ12VYONLNF
2019-8-24
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JeremyMelbourne
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JJB* Posted at 8-24 07:17
Hi Jeremy,

without reading out a flightlog it is hard to give some comments.

https://www.phantomhelp.com/LogViewer/7C6B36EX2OZ12VYONLNF
2019-8-24
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JeremyMelbourne
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JeremyMelbourne Posted at 8-24 23:14
https://www.phantomhelp.com/LogViewer/7C6B36EX2OZ12VYONLNF

if you guys can look at that log above, is there more information in other logs with more detail? list of commands send and detailed sensor data? that log seems pretty simplistic
2019-8-24
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JJB*
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Hi Jeremy,

Nothing weird in your log. Your setting was to fly to home if connection lost.

So after loosing connection your M2 should retrace its route and finally fly back home.
If i look in GE, and i draw a line last postion to home, the line crosses a tall building (height?, flying at 99 meter) . But retracing its route it should fly south along that building.

If DJI tells you that your drone flew into a buidling...how do they know?  if based on this data, guess they missed that retrace route.

So i have no idea what happend.

BTW pressing RTH after a full disconnect does not work, as this command never reaches the drone due to connection loss.
cheers
JJB

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2019-8-25
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JeremyMelbourne
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Hello, thanks for that information. I have been very disappointed with DJI support. I think they have outsourced it to a call centre of some sort. I firmly believe there is an issue with the drone and the loss of signal and return home function. As I mentioned I have had Phantom 3/4/Pro previously and I have had loss of signal often. The drone would just fly to max altitude set and return home, as it should. I have looked at that building that you refer to. I rode over to it. It is less than my RTH altitude setting, so it doesn't make sense it would hit it.
2019-8-25
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JJB*
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JeremyMelbourne Posted at 8-25 01:24
Hello, thanks for that information. I have been very disappointed with DJI support. I think they have outsourced it to a call centre of some sort. I firmly believe there is an issue with the drone and the loss of signal and return home function. As I mentioned I have had Phantom 3/4/Pro previously and I have had loss of signal often. The drone would just fly to max altitude set and return home, as it should. I have looked at that building that you refer to. I rode over to it. It is less than my RTH altitude setting, so it doesn't make sense it would hit it.

oke, my advice is to get a second opinion via one of the DJI people on here.

Cannot believe that DJI will let you down like this, seeing your flightlog.

Good luck
Cheers
JJB

2019-8-25
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A J
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Sorry to read that - hope you get it sorted soon
2019-8-25
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hallmark007
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JJB* Posted at 8-25 01:27
oke, my advice is to get a second opinion via one of the DJI people on here.

Cannot believe that DJI will let you down like this, seeing your flightlog.

I think there are a few suspect things here, first OP said Rth was set at 150m , not correct it was 80m , he then said he lost video feed and he wasn’t near any buildings this is also not true, he was flying directly above the buildings. And last he said he lost video feed then RC yet none of this is reported in his flight log, which is just a little strange, from his log we can see his last stick movements were down 100% before log ends, we have no way of knowing Rth was initiated because RC as OP said was disconnected.
2019-8-25
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Gimpy
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JeremyMelbourne Posted at 8-25 01:24
Hello, thanks for that information. I have been very disappointed with DJI support. I think they have outsourced it to a call centre of some sort. I firmly believe there is an issue with the drone and the loss of signal and return home function. As I mentioned I have had Phantom 3/4/Pro previously and I have had loss of signal often. The drone would just fly to max altitude set and return home, as it should. I have looked at that building that you refer to. I rode over to it. It is less than my RTH altitude setting, so it doesn't make sense it would hit it.

There are at least a couple of mistakes in JJB's analysis, and I'm sorry to say that I have to agree with DJI.

First, on RTH, the aircraft would not have retraced its entire route back to you as he claimed, but only the last 60 seconds of flight before traveling straight back. Looking at your log and the map, that means it probably tried to cross the northeast corner of the Wyndham Soleil Danang building complex. JJB said it would have traveled back at 99 meters, but the log indicates that your RTH height was set at 80 meters, and both are well below the 57-story building's 199 meter height. In other words, your RTH would have needed to be set to at least 200 meters to clear the building. That's higher than most countries allow you to fly, but I'm not familiar with Vietnam's regulations, and a quick Google search didn't turn up any mention of a height restriction or even a requirement to maintain line of sight.

So, like DJI, I suspect that it either crashed into the building or eventually depleted its battery and landed near the building. I'm guessing that DJI told you that you should have maintained visual line of sight and / or set your RTH higher than the tallest potential obstacle, and while I'm sympathetic to your loss, I'd have to agree with them and their assessment in this case.
2019-8-25
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JJB*
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Gimpy Posted at 8-25 05:03
There are at least a couple of incorrect statements in JJB's analysis, and I'm sorry to say that I have to agree with DJI.

First, on RTH, the aircraft would not have retraced its entire route back to you as he claimed, but only the last 60 seconds of flight before traveling straight back. Looking at your log and the map, that means it probably tried to cross the northeast corner of the Wyndham Soleil Danang building complex. JJB said it would have traveled back at 99 meters, but the log indicates that your RTH height was set at 80 meters, and both are well below the 57-story building's 199 meter height. In other words, your RTH would have needed to be set to at least 200 meters to clear the building. That's higher than most countries allow you to fly, but I'm not familiar with Vietnam's regulations, and a quick Google search didn't turn up any mention of a height restriction or even a requirement to maintain line of sight.

Hi Gimpy,

Ofcourse it does retrace only for 1 minute, guess we all know that.
You are right, if you read my post with no or less knowledge, yes you are right. I have to be more precise.

To my knowlege, if a DJI drone flys higher than the RTH setting it will not descend but fly`s back at the height is was flying when loosing connecting.[ just checked the M2 manual, yes, it will fly back at current alt ]
So last height was 98.9, RTH height setting 80 meters. So fly height back to HP = 99 meters.

If the OP says that that building is not that high. who am i to discuss that.

If i retrace its route back for 60 seconds, from that position draw a line back to homepoint it stays well clear of that buidling. But just my opinion.
If i am wrong, no problem.

Question is how DJI can tell the OP that his drone crashes into a building?? wich data did they use to make that point??

cheers
JJB
2019-8-25
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Gimpy
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JJB* Posted at 8-25 05:19
Hi Gimpy,

Ofcourse it does retrace only for 1 minute, guess we all know that.

It's very obvious that you didn't know that the drone only retraces the last sixty seconds; you wrote that "your M2 should retrace its route and . . . fly south along that building", but I understand that it's embarrassing for you to be wrong again and be corrected.

As for how DJI "knows" what happened, they don't know, but they make assumptions as you and I do based on the content of the log, and the logical assumption in this case is that it crossed the path of the tall building. Ironically, you yourself have claimed to know things you clearly don't but now you're criticizing DJI for making similar assumptions based on the log content. Remember our discussion / debate about someone else's height above water where you claimed to know the exact height despite the conflicting VPS / barometer readings?
2019-8-25
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JJB*
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Gimpy Posted at 8-25 05:25
It's very obvious that you didn't know that the drone only retraces the last sixty seconds; you wrote that "your M2 should retrace its route and . . . fly south along that building", but I understand that it's embarrassing for you to be wrong again and be corrected.

As for how DJI "knows" what happened, they don't know, but they make assumptions as you and I do based on the content of the log, and the logical assumption in this case is that it crossed the path of the tall building. Ironically, you yourself have claimed to know things you clearly don't but now you're insisting that DJI can't know things. Remember our discussion / debate about someone else's height above water where you claimed to know exactly how high above the water it was despite the conflicting VPS / barometer readings?

HaHa, if that you makes you happy,  just read other postings from me about retracing routes.
Ofcourse i do know this 60 second behaviour.

For this case, if this M2 flys back in a RTH procedure, the fwd and aft obstacles are working.
So it should see a tall building and act like it is described in the manual.

You do not answer my question, how does DJI know it crashed into a building, as this file does not explain this? Does the DAT file have more info about this? don`t think so as it is on the mobile device too. Other DAT file in the craft is not available....

Ofcourse i remember our 'height' discussion, nothing to do with this flight.
( and yes, within logical engineering i was so right about that height  :-0, so don`t start this discussion again please or use it as to 'prove' something )

BTW checked that area, lots of high building there now! and indeed higher than 99 meters.

cheers
JJB

2019-8-25
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Gimpy
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JJB* Posted at 8-25 05:40
HaHa, if that you makes that happy,  just read other postings from me about retracing routes.
Ofcourse i do know this 60 second behaviour.

I'll leave it as an exercise for the readers to determine whether you considered the 60 second retracing based on your own words and the image you attached showing the original path to the south of the building, which you predicted his drone should / would have re-flown. Here's what you wrote:

"So after loosing connection your M2 should retrace its route and finally fly back home.
If i look in GE, and i draw a line last postion to home, the line crosses a tall building (height?, flying at 99 meter) . But retracing its route it should fly south along that building.

If DJI tells you that your drone flew into a buidling...how do they know?  if based on this data, guess they missed that retrace route."

DJI "knows" more than you, and as you've shown repeatedly, your confidence exceeds your actual knowledge of how things work. And yes, that other thread is relevant, because in it you claimed to "know" things based on what's in the log, despite the fact that you're now criticizing DJI for doing the very same thing.

2019-8-25
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hallmark007
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JJB* Posted at 8-25 05:40
HaHa, if that you makes that happy,  just read other postings from me about retracing routes.
Ofcourse i do know this 60 second behaviour.

1/ how do you know it was in Rth , 2/ last known mode for craft sport , will OA work in RTH in Sport ?
I’m simply amazed you give this offering of almost certainty that the OP was in No way responsible, if you judge on what we actually know instead of surmising on what could have happened I think a much more practical and fair reflection would be given to OP.

We know OP was flying BVLOS we know he had lost video connection, we know from his flying and in the environment he was flying in he was not risk averse, ie a lot of his flight was at altitude 200m also flying in an area that could be fraught with signal problems.
I think it’s best in these situations to be objective, but not to make clear statements to the OP that this had nothing to do with him.
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hallmark007 Posted at 8-25 06:01
1/ how do you know it was in Rth , 2/ last known mode for craft sport , will OA work in RTH in Sport ?
I’m simply amazed you give this offering of almost certainty that the OP was in No way responsible, if you judge on what we actually know instead of surmising on what could have happened I think a much more practical and fair reflection would be given to OP.

Hi Hallmark,

1) Do i know if this drone was in a RTH?  nope, but after loosing contact it should be in RTH, in the manual a M2 enters Fail safe RTH after 2 seconds of a disconnect.
2) When loosing contact DJI drones fall into RTH, AFAIK it does not matter if that is from a SPORT or P-GPS mode. Fail safe RTH = OA enabled, if he manual is correct.
3) I never said anything about his not being responsible. Guess that is a magic word for you.
4) Yes, OP was not in LOS, clever? mayby not but his choice. DJI software doesn`t know if a drone is in LOS or not. I am not to judge about choices people make how to fly a drone.
5) if only a video loss was there, data of the flight is written in the file. Not in this file so at the end a full disconnection.
6) flying at 200 meters height, most probably not allowed there. Same as flying BVLOS, SW drone does not act in a different way < 120 meter or > 120 meters height.

Guess his connection was lost because LOS RC>DRONE was disturbed by the high buildings in between.
But it should return to home, batt 77% so flying time enough i would say.
So do not start always when people looses their drones that its their responsibiliy and  am denying that fact, i fully agree on that with you in most cases.
And yes, his post doesn`t reflect the situation, some height info was incorrect. But mayby the OP really thinks that his text was completely right, its how people remember things and think they did nothing wrong. Not for me to react on, just see the fact written in the log to get a opinion.

In principal i believe in people. So if the OP stated that a DJI help desk stated that his drone flew against a building? how do they know that ??

EDIT i see a high warning in the file Ambient Light too Weak. "Vision Positioningobstacle sensing is unavailable..please ensure safety during the flight" So most likely the OA did not work at the fail safe RTH. As i cannot say excactly from where the drone flew direct home (after 60s retracing), i cannot say if in that direct line a tall building was there....if yes, than it may have hit that building.

cheers
JJB



2019-8-25
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hallmark007
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JJB* Posted at 8-25 10:43
Hi Hallmark,

1) Do i know if this drone was in a RTH?  nope, but after loosing contact it should be in RTH, in the manual a M2 enters Fail safe RTH after 2 seconds of a disconnect.

For me I don’t believe this drone was in Rth mode, there is no evidence of this including the log, you say dji shouldn’t say he crashed into a building because YOU think it’s not in device log. But at the same time you feel it’s fine to say craft was in RTH when log shows absolutely no evidence of this, you can’t have your cake and eat it.

I see you constantly telling people their satellite count was low, but shy away from telling others they were clearly out of line of site, which in this case could well have been detrimental, and is more likely the case, so again having your cake and eating it.

As I said, I think the problem here is, this accident equally looks like it could well have been an error by pilot, but you choose to completely ignore all of the evidence simply because you nailed your colors to the mast without duly studying exactly what may have occurred .

I constantly see you doing this, and then further more totally defending your position when others find it is not What it seems,  but I wonder does it help not to give the OP all of the possibilities instead of just telling him he was at no fault , which as can easily be seen here in this case , not only by me .

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hallmark007 Posted at 8-25 11:09
For me I don’t believe this drone was in Rth mode, there is no evidence of this including the log, you say dji shouldn’t say he crashed into a building because YOU think it’s not in device log. But at the same time you feel it’s fine to say craft was in RTH when log shows absolutely no evidence of this, you can’t have your cake and eat it.

I see you constantly telling people their satellite count was low, but shy away from telling others they were clearly out of line of site, which in this case could well have been detrimental, and is more likely the case, so again having your cake and eating it.

uh,  you and Gimpy likes to discuss but not going into arguments at all. Saying incorrect thing about RTH height and saying does OA works in Sport ?

Never mind, your reaction is so silly and non logical that i think you like to makes fools of others to say all this. Well, doesn`t work you know, people with brains will always win on here.

Ofcourse there is no evidence in the file of a Fail Save RTH ,  as there is no connection to the RC !!
Hard to understand? Sometimes there is as the connection is rte-established. Not in this file.

Read my post #27 again and you will understand that i think i know what happend.
But feel free to think differently!

cheers
JJB
2019-8-25
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hallmark007
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JJB* Posted at 8-25 11:30
uh,  you and Gimpy likes to discuss but not going into arguments at all. Saying incorrect thing about RTH height and saying does OA works in Sport ?

Never mind, your reaction is so silly and non logical that i think you like to makes fools of others to say all this. Well, doesn`t work you know, people with brains will always win on here.

“There's none so blind as those who will not listen.”

It seems that around here your the only one who is ever right, the sixty second rule in Rth , it was indeed me who brought this to your attention after your usual “can you point this out to me” you will also read in my post I didn’t say that craft will return without OA I merely asked the question, so maybe you will point out to me where it says in the manual that when you lose signal in sport mode your craft reverts to P mode and returns with OA , we do know that for instance that spark Rth can operate without OA.

And like I said No evidence of either lost connection or lost video signal, but OP says he lost video and RC , dji say he crashed, you say dji can’t say this but OP can say what he likes.

It’s quite possible that lost video and RC came as a direct result of a crash.

If you read what you wrote it was more than clear you never mentioned anything about 60 seconds and then Rth directly, but instead of admitting to a mistake you squirm, they call that pig headed, and it seems if anyone disagrees with you they face the same mantra, the truth is although you believe your a legend in your own lunchtime, it has been found here many many times your analysis can be very skewed and often totally wrong.

You seem to be fond of blowing your own trumpet, but as they say self praise is no praise . I wonder when OP gets no comeback from dji, will you continue to say YOUR BRAIN was right .
2019-8-25
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djiuser_IJ7oTXK2Xt8l
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Since you've gotten two different opinions on whether DJI's analysis was right, why don't you post your log over on MavicPilots? There are some guys there who do a lot of this kind of analysis, including msinger whose PhantomHelp web site you uploaded your logs to.
2019-8-25
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djiuser_IJ7oTXK2Xt8l
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Sorry, here's the link:

https://mavicpilots.com/forums/mavic-crash-flyaway-assistance.85/
2019-8-25
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JJB* Posted at 8-25 10:43
Hi Hallmark,

1) Do i know if this drone was in a RTH?  nope, but after loosing contact it should be in RTH, in the manual a M2 enters Fail safe RTH after 2 seconds of a disconnect.

JJB - sorry if this question sounds redundant, but I ask only that you seem to be quite a knowledgeable member of the community and I know we're speaking on the topic of Failsafe RTH, but have you ever experienced a Failsafe RTH? What is the furthest distance you've taken one of your DJI drones before disconnect, if you don't mind me asking?
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David Martin Graff Posted at 8-25 19:27
JJB - sorry if this question sounds redundant, but I ask only that you seem to be quite a knowledgeable member of the community and I know we're speaking on the topic of Failsafe RTH, but have you ever experienced a Failsafe RTH? What is the furthest distance you've taken one of your DJI drones before disconnect, if you don't mind me asking?

Hi David, yes i have experienced a fail safe RTH with my MA, just once in many flights.
It did a great retrace of the route and finally flew back in a direct line to HP.

I do not push the distance limits with my drones, no need to to that.

cheers
JJB
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hallmark007 Posted at 8-25 12:13
“There's none so blind as those who will not listen.”

It seems that around here your the only one who is ever right, the sixty second rule in Rth , it was indeed me who brought this to your attention after your usual “can you point this out to me” you will also read in my post I didn’t say that craft will return without OA I merely asked the question, so maybe you will point out to me where it says in the manual that when you lose signal in sport mode your craft reverts to P mode and returns with OA , we do know that for instance that spark Rth can operate without OA.

Nice saying but do some self reflection.

This forum is to help others, i try to explain what happend or could have happend to a drone when it crashes or et lost etc.

Your contributions to this thread is to disagree with me (no problems with that), but not by counter my arguments and explain you think what has happend. No just say i am wrong and you believe somnehing else. Next to this you never react on my asked questions, but try to mist-out that and just ignore things.

If i say that i do know about 60 secs, you do not believe me. You have a nasty feeling about other people, does say more about you than about me.
If i have the knowledge of retracing, what is the chance that i missed that 60s ? Same as putting your car in first gear and not knowing that you have #2, N3 etc gear as well.


In the M2 manual is described what happens if a fail safe RTH gets active, active and OA are active as well. It does not warn us that when a RTH started from a Sport mode means that OA is not active!
Doesn`t make sense, so logical thinking OA is working in a fail save RTH.

OP stated that DJI told him that his M2 crashed into a building. Positon Last record was not near a buidling, so what happend after the last recorded record is a question to be answered.
Crashed into a builidng? mayby yes but how do they know?? If DJI told him that his drone probably crashed into a building..., mayby they did say that.

We can disagree about my analysis on here, if you think that i am often totally wrong be my guest.
Hope that next times you will counter my arguments with knowledge and facts and not just with feeling based mayby on frustration (or what else?)

Mayby that`s why you now started to refer to other threads, just to blackening me.

See you in other threads and please do counter me with arguments.

Just give my opnion about drone mishaps on here, in my world that is not blowing a trumpet or self praise.

cheers
JJB



2019-8-25
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hallmark007 Posted at 8-25 12:13
“There's none so blind as those who will not listen.”

It seems that around here your the only one who is ever right, the sixty second rule in Rth , it was indeed me who brought this to your attention after your usual “can you point this out to me” you will also read in my post I didn’t say that craft will return without OA I merely asked the question, so maybe you will point out to me where it says in the manual that when you lose signal in sport mode your craft reverts to P mode and returns with OA , we do know that for instance that spark Rth can operate without OA.

There are some interesting comments here that seem to be focussing on what people have said, but I think the main focus should be that the OP originally stated he was nowhere near any buildings when the flight logs show he was literally flying through a sea of buildings.
In addition, he stated the RTH altitude was 150 m when it was only 80m according to the logs.

Discussions of RTH behaviour are valid enough but ultimately if there were buildings higher than the RTH altitude and possibly higher than the actual flight altitude, then this was a bad choice of flight location.   
Flying in Sports Mode disables the collision sensors, which again was a very poor move given the location.  For there to be an 'Ambient Light' warning implies this may have been at dusk. If so, even worse decision.

It's always really sad to read about someone's loss, but I get frustrated when they try and blame DJI for their own poor choices and make misleading comments on an opening post.  This is my opinion on what's happening here.   A bad location and a poor choice of flight path.  Many of us have made similar poor choices in the past, myself included, but be truthful and clear in what went wrong and learn from it. Don't try and just mislead others into thinking it's equipment failure and DJI's fault when in reality it's the pilot's own poor decisions that have resulted in the loss.  
2019-8-25
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JJB*
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Hi Jeremy,

To make this thread readible for all, my thoughts what happend to your M2.

1) Lost connection at 6m3.1s, flying in SPORT mode, distance out 629 meters, height 98.9 meters.
2) Why a full disconnect (as no data is written in the log after this), my guess because LOS RC>M2 is blocked by high buidlings in between.
3) Fail safe RTH becomes active. (assumption ofcourse, but a M2 should, after 2 secs of disconnection, enters a fail safe RTH)
4) M2 retrace its route for 60 seconds. ( in the manual afaik nothting said about fly speed in 'retrace mode', so how far it flew back in distance is hard to tell)
4) After 60 seconds with still no connection M2 will fly in a direct line to HP
5) Normally in fail save RTH OA does work, but due to low light conditions your OA did not function!
(see warning at 4m25s about this)
6) RTH height at 99 meters, RTH setting 80 meters. So M2 will not descend to 80 meters as it flying higer)
7) As it did not return to home...my guess is that it hit an obstacle on his way back home. Seeing the high building complex (height > 99 meters!) in that area, what else could bring this M2 to a 'stop'?
So what went wrong;

1) flying BVLOS ; not the cause of this mishap. (mayby not wise to do so, but not judging here)
2) Flying behind and not above high buildings, disconnect happend when height was lowered from 122 meters to 99 meters, hovering at steady 625 meters.
3) Setting RTH height at 80 meters ; should be higher than the highest buidling ; not the main cause of this mishap.
4) Ignoring the warning Low Ambient light....taking a risk do continue flying, if only the RTH height setting was above that building.

Combination of 4) and 3) is the cause of your loss; IMO if RTH height setting was set at a value good for this area, your M2 had return to the HP in a fail safe RTH 'mode'.

For all readers ; if you disagree about what i think did happen; 'shoot' my arguments away and explain what you think did happen (while i play my trumpet )

Many happy landing to you all,
cheers
JJB





2019-8-26
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Aardvark
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For me the one bit in the OP that sets off an alarm is:-

"I pressed the RTH button a few times and waited."

So if there were an RTH in progress (loss of signal), and it receives a spurious RTH command from the RC after the initial RTH activated, then that will cancel any RTH.

It seems it was a high risk flight in a built up area.

2019-8-26
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G_Sig
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JJB* Posted at 8-26 00:08
Hi Jeremy,

To make this thread readible for all, my thoughts what happend to your M2.

I think you are mostly right about this other than the 2 sec to active RTH.
The Manual is wrong about that 2 sec time and the flight log show that.
If there is missing a 0 in the Manual or the app still has some sort of connection
without logging any data I simply don't know.
Just for the record that time has nothing to do with the outcome in this case, just pointing out.
2019-8-26
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G_Sig Posted at 8-26 01:41
I think you are mostly right about this other than the 2 sec to active RTH.
The Manual is wrong about that 2 sec time and the flight log show that.
If there is missing a 0 in the Manual or the app still has some sort of connection

Thanks, G-Sig, not 2 seconds but how much than ?

Other types i believe 3 or 4 seconds.

Not 100% sure about the following but,

About the flightlog ;
if only the video feed is lost, data is still logged into the file every 0.1 second.
If only the data down stream is lost, no data logging but no RTH after some seconds.
If data upstream is lost (so drone knows that it does not receive RC signals) a RTH will become active after few secs.
So in this log at the end i see only 2 times a partly loss of comms.



cheers
JJB
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2019-8-26
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Aardvark Posted at 8-26 01:29
For me the one bit in the OP that sets off an alarm is:-

"I pressed the RTH button a few times and waited."

yes,  good observation. Thanks for adding it to my 'knowledge'

cheers
JJB
2019-8-26
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JJB* Posted at 8-25 23:37
Nice saying but do some self reflection.

This forum is to help others, i try to explain what happend or could have happend to a drone when it crashes or et lost etc.

So you base your assessment on knowledge , but what knowledge “None” because there was none, except what OP said, but what you tried to do with that was be selective to suit your theory and this is exactly what I did , but the difference is you come along here and tell us what happened with no evidence, I come here and express from my deductions what Could have happened.

I have in earlier post pointed out, there was no evidence in flight log as to any disconnect or any signal to RC being lost, or any attempt by OP to press RTH.
But there was evidence he clearly didn’t know where he was, as you know he said he was nowhere near any buildings, he also said RTH height was set at 150m, enough to cover all obstacles, we know he was flying in a risky environment in sport mode sometimes at heights over 200m.
All of above we found out from the flight log, the OP never alerted us to any of this, instead he told us signal was lost craft went to RTH and he again pressed Rth , it seems according to you that we should accept that signal was lost and Rth initiated “why” because OP told us, but we should not deduct the fact that the only evidence we have was a log that showed no problems, and we should ignore the fact that the OP failed to tell us all he didn’t know where he was , he wasn’t near any buildings etc.

I also don’t believe for a single minute that dji would tell you that craft crashed into a building if they had no proof, it’s always pretty clear around here when similar happens without proof, that dji  will make the same statement, we can see no craft malfunction no pilot error and best we can do is offer you 30% discount .

For me the OP was very selective in telling us what happened here, and the fact that he hadn’t a clue where he was leads me to believe that it’s LIKELY he just crashed.

It is also very common in viewing logs of crashes, that the last few seconds are NOT RECORDED, so log can’t prove this didn’t or did happen.
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2019-8-26
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Wellsi Posted at 8-25 23:44
There are some interesting comments here that seem to be focussing on what people have said, but I think the main focus should be that the OP originally stated he was nowhere near any buildings when the flight logs show he was literally flying through a sea of buildings.
In addition, he stated the RTH altitude was 150 m when it was only 80m according to the logs.

I fully agree and I do believe this was a crash simply because OP had no clue where he was flying, no clue of parameters he had set, and doing so in a pretty reckless manner.
While there is no proof that that this is what happened, there is more proof that it is a lot more likely than an aircraft malfunction .
2019-8-26
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JJB* Posted at 8-26 00:08
Hi Jeremy,

To make this thread readible for all, my thoughts what happend to your M2.

Regarding OA in RTH . The aircraft cannot avoid obstacles in Failsafe if obstacle avoidance is not available, we are all aware that switching to S mode turns off OA, so while manual clearly points out what I’ve written above, nowhere does it say that OA will automatically turn on in failsafe if craft is in S mode, in fact it can give a complete different explanation above, and this is why I raised the question.

So we know in S mode craft turns off OA, it doesn’t say anywhere in the manual that it will auto switch back on in Failsafe, in fact you may well be led to believe they are not available if you turned them off, IE switched to S mode.
2019-8-26
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