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RTH problem

EllyBrandi

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Hi, I hope someone can help. My flight involved a short session where I had the drone (Mavic 2Pro) follow me. I had taken off and as usual the drone updated home point and gave the all clear to fly. I travelled about 150 meters and did some video footage and also some still photography. I was flying only about 3 or 4 meters away from myself when a warning appeared saying low battery please return to home (set to 21 percent)
As I was 150 meters away from the take off point I decided to land at my current location. I flew close and selected what I deemed to be a suitable landing spot and another warning came up saying there was only enough battery left to RTH and return immediately (something like that anyway). I was concerned because the battery was still showing 18 Percent and I thought this should have been plenty to go up 30 meters (RTH height I set) and travel the 150/160 meters home so I began to worry that the home point was in error. I tried to land by holding the right stick fully down (I fly mode 1) but the drone refused to come down and when I let go of the stick it started to rise. By this time the battery level was dropping rapidly (much faster than I thought it should ) so I thought I would hand catch it and force a landing. I held the stick back and as usual the drone reacted to my hand being in the way and normally it will come back down when you continue to force the landing. This time it didn't. Every time I tried to grab it , it went UP. In desperation I had to get as close as I could then launched myself at it and grabbed it. With the stick still fully back the drone did not throttle down. I turned it on its side and it then shut off.
I am happy to accept the blame for this , all I want to do is find out where I went wrong so it doesn't happen again.
I have checked the battery and it comes up ok. I checked the home point and it is correct. I have hand caught the drone previously without any problems. I feel that the battery level decreased very quickly at the end and I'm not sure why.
I have attached the flight log and hope someone will be able to help,
Thanks.
 

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Hi, I hope someone can help. My flight involved a short session where I had the drone (Mavic 2Pro) follow me. I had taken off and as usual the drone updated home point and gave the all clear to fly. I travelled about 150 meters and did some video footage and also some still photography. I was flying only about 3 or 4 meters away from myself when a warning appeared saying low battery please return to home (set to 21 percent)
As I was 150 meters away from the take off point I decided to land at my current location. I flew close and selected what I deemed to be a suitable landing spot and another warning came up saying there was only enough battery left to RTH and return immediately (something like that anyway). I was concerned because the battery was still showing 18 Percent and I thought this should have been plenty to go up 30 meters (RTH height I set) and travel the 150/160 meters home so I began to worry that the home point was in error. I tried to land by holding the right stick fully down (I fly mode 1) but the drone refused to come down and when I let go of the stick it started to rise. By this time the battery level was dropping rapidly (much faster than I thought it should ) so I thought I would hand catch it and force a landing. I held the stick back and as usual the drone reacted to my hand being in the way and normally it will come back down when you continue to force the landing. This time it didn't. Every time I tried to grab it , it went UP. In desperation I had to get as close as I could then launched myself at it and grabbed it. With the stick still fully back the drone did not throttle down. I turned it on its side and it then shut off.
I am happy to accept the blame for this , all I want to do is find out where I went wrong so it doesn't happen again.
I have checked the battery and it comes up ok. I checked the home point and it is correct. I have hand caught the drone previously without any problems. I feel that the battery level decreased very quickly at the end and I'm not sure why.
I have attached the flight log and hope someone will be able to help,
Thanks.
Hi there ... this isn't any mystery actually. You didn't cancel the RTH mode once it was initialized, instead you were fighting it.

Looking into the flight log clearly show the 10sec RTH count down (which you didn't cancel) as the green graph. The battery level for this RTH to happen was 19% (dark green graph) so when the battery reached that level (black graph), with you not cancel the countdown it started to RTH where I have placed the markers in the chart. From there (the greenish background color) you were fighting the ascending with your right stick (blue graph) .

(Click on the chart to make it larger)

1601636713417.png
 
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I have attached the flight log and hope someone will be able to help,
Your flight data looks like this: DJI Flight Log Viewer - PhantomHelp.com

The drone entered RTH at 19:23.6 and you fought RTH until 20:28.8.
Once the drone is in an automated flight mode like RTH, the programming for the automated flight mode is in control.
Unless you cancel the automated flight mode, it's going to keep trying to do what it's programmed to.

If you flicked the Flight Mode switch out of P-GPS and back, that would have quickly cancelled the RTH and left the drone waiting for your control input.
 
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I tried to land by holding the right stick fully down (I fly mode 1) but the drone refused to come down and when I let go of the stick it started to rise. By this time the battery level was dropping rapidly (much faster than I thought it should ) so I thought I would hand catch it and force a landing. I held the stick back and as usual the drone reacted to my hand being in the way and normally it will come back down when you continue to force the landing. This time it didn't. Every time I tried to grab it , it went UP. In desperation
I apologize but I got lost here. For clarity;

You held the throttle down and the drone did not decrease in altitude.

Then you somehow forced a landing. How did you do this? Did the drone then decide to respond to the throttle being held down the second time?

In regard to the drone moving up when you placed your hand under it, you can disable the bottom/landing sensor in the app to make a hand landing easier. Having said that, I've always had the drone shut down after I grab it if I hold the throttle down long enough. It will fight with me for a few seconds prior to reducing propeller speed and shutting down.
 
Hi, I hope someone can help. My flight involved a short session where I had the drone (Mavic 2Pro) follow me. I had taken off and as usual the drone updated home point and gave the all clear to fly. I travelled about 150 meters and did some video footage and also some still photography. I was flying only about 3 or 4 meters away from myself when a warning appeared saying low battery please return to home (set to 21 percent)
As I was 150 meters away from the take off point I decided to land at my current location. I flew close and selected what I deemed to be a suitable landing spot and another warning came up saying there was only enough battery left to RTH and return immediately (something like that anyway). I was concerned because the battery was still showing 18 Percent and I thought this should have been plenty to go up 30 meters (RTH height I set) and travel the 150/160 meters home so I began to worry that the home point was in error. I tried to land by holding the right stick fully down (I fly mode 1) but the drone refused to come down and when I let go of the stick it started to rise. By this time the battery level was dropping rapidly (much faster than I thought it should ) so I thought I would hand catch it and force a landing. I held the stick back and as usual the drone reacted to my hand being in the way and normally it will come back down when you continue to force the landing. This time it didn't. Every time I tried to grab it , it went UP. In desperation I had to get as close as I could then launched myself at it and grabbed it. With the stick still fully back the drone did not throttle down. I turned it on its side and it then shut off.
I am happy to accept the blame for this , all I want to do is find out where I went wrong so it doesn't happen again.
I have checked the battery and it comes up ok. I checked the home point and it is correct. I have hand caught the drone previously without any problems. I feel that the battery level decreased very quickly at the end and I'm not sure why.
I have attached the flight log and hope someone will be able to help,
Thanks.
The flight was already very well analyzed by the experts above. As to your question about what you did wrong, or could do better in order to avoid this in the future:
  • You flew too long. Everyone has their own margin of safety, but I always personally try to be back on the ground BEFORE my battery hits 30%. It doesn't matter how far the drone is from home or how little flying I need to still accomplish. This type of safety margin leaves plenty of power for unforeseen circumstances and also leaves the battery at a good charge level for storage.
    There is no point in trying to stretch the maximum time out of a battery. It can lead to incidents (like yours), leaves little margin for error and causes pilot panic, and drains the battery to very low levels.
  • You were not fully aware of the proper procedures for your drone. If you had known and previously practiced emergency procedures, you could have cancelled the RTH and landed safely.
  • You disregarded the drone's built-in safety mechanisms. When the drone says it needs to RTH for low battery reasons, believe it. It doesn't just pick a random time to RTH. It calculates the needed battery time needed to travel the distance back to home and initiates the process when it feels that it must do so. Of course, if you follow step 1 above, you should never get into this situation.
 
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Thanks for your input. In my defence I was only about 3 to 4 meters away from the drone when I received the warning of 21 percent remaining battery. I immediately decided to land at my feet rather than fly the 150 meters to the take off point. I had 2 warnings appear on my screen which I cancelled by touching the X. Unfortunately I couldn’t read the actual messages because I was in direct sunlight but I assume that the previous responder to my post was correct and it was the RTH warning. I thought I had cancelled it but apparently not. My main concern was the rapid decrease in battery level. I would have thought that I should have had been able to land safely as I only had 4 meters to go and I have seen video of pilots flying to much lower battery levels. As a radio control flyer of electric aircraft I avoid flying below 20 percent battery level and this is why I had my drone set to 21 percent. I also make sure that I am not a kilometre away when approaching low battery.
Thanks again for your input, we can all learn from experience.
 
Your flight data looks like this: DJI Flight Log Viewer - PhantomHelp.com

The drone entered RTH at 19:23.6 and you fought RTH until 20:28.8.
Once the drone is in an automated flight mode like RTH, the programming for the automated flight mode is in control.
Unless you cancel the automated flight mode, it's going to keep trying to do what it's programmed to.

If you flicked the Flight Mode switch out of P-GPS and back, that would have quickly cancelled the RTH and left the drone waiting for your control input.

Thanks for your response, I cancelled 2 warning messages that appeared but I was caught in direct sunlight and whilst I cancelled the messages I couldn’t read what they said (lesson learned)
I assume that you are correct and I didn’t cancel the RTH. I was surprised that the RTH was initiated so close to the low battery warning as I only had 3 or 4 meters to fly. Thanks for your response, I will set my low battery warning at a higher level for future flights!
 
Glad you figured out your issues. Most of us including my self, did not understand how the RTH feature works. Even if we have been flying for a number of years. On my MP, I have two low battery warnings, one 30% and another at 10%. And, I never use the LOW BATTERY RTH. The Low Battery RTH is a different scenario. When the MAVIC detects it only has enough power to make it back to the Home point. Low Battery RTH will be initiated and a message will be displayed on the screen in DJI Go to alert you that your aircraft is going to Auto RTH in 10 SECONDS.And, you know the rest of the story. I don't like using it because its just the same when a pilot sees his low fuel light blinking and has to land quick in a open field. I try to get it home by the time the 10% message goes Off, and fly home manually. The RTH feature is one of the most complex features of a DJI drone. There are many other possible scenarios that could occur when RTH is instiated. Carefully review the RTH section of the manual to fully understand it .Many important things to know. I have had my ups and down with RTH myself in the early stages of learning. But, always experimented in a wide open field, so I knew what it was going to do in each feature. Fly Safe.
 
Glad you figured out your issues. Most of us including my self, did not understand how the RTH feature works. Even if we have been flying for a number of years. On my MP, I have two low battery warnings, one 30% and another at 10%. And, I never use the LOW BATTERY RTH. The Low Battery RTH is a different scenario. When the MAVIC detects it only has enough power to make it back to the Home point. Low Battery RTH will be initiated and a message will be displayed on the screen in DJI Go to alert you that your aircraft is going to Auto RTH in 10 SECONDS.And, you know the rest of the story. I don't like using it because its just the same when a pilot sees his low fuel light blinking and has to land quick in a open field. I try to get it home by the time the 10% message goes Off, and fly home manually. The RTH feature is one of the most complex features of a DJI drone. There are many other possible scenarios that could occur when RTH is instiated. Carefully review the RTH section of the manual to fully understand it .Many important things to know. I have had my ups and down with RTH myself in the early stages of learning. But, always experimented in a wide open field, so I knew what it was going to do in each feature. Fly Safe.

Thanks. I will be reading the RTH section in detail. I was under the mistaken impression that if you held the stick down the M2P RTH would be overridden and it would land. What I misunderstood on the day was that when I let go of the stick the M2P started to ascend and when I pulled the stick back again it did in fact descend but only to about 6 ft where it would go no lower. My main concern in trying to make a quick judgement was that if the home point was somehow in error then the aircraft could be going anywhere. I was also not aware as a previous responder said that if you flick the mode switch it will cancel RTH.
Thanks for you time and help, regards JH.
 
I apologize but I got lost here. For clarity;

You held the throttle down and the drone did not decrease in altitude.

Then you somehow forced a landing. How did you do this? Did the drone then decide to respond to the throttle being held down the second time?

In regard to the drone moving up when you placed your hand under it, you can disable the bottom/landing sensor in the app to make a hand landing easier. Having said that, I've always had the drone shut down after I grab it if I hold the throttle down long enough. It will fight with me for a few seconds prior to reducing propeller speed and shutting down.

Hi. This was part of my misunderstanding RTH. When I got the low battery warning at 21% I was only 4 meters away. The home point was over 150 meters away so immediately I got the message I flew the 4 meters to land. In the time it took to manoeuvre that distance apparently the RTH was initiated. The drone started to ascend so I pulled back on the stick. The drone descended and got to about 2 meters but would not go any lower. The log shows my input. I let go of the stick and the drone started to go up so I pulled down and held it down for the remainder of the time. I tried to grab the drone but of course it went up again until my hand was not in the way. On about the 3rd attempt of trying to avoid the sensors I managed to launch at it and hold on. A comedy of errors that will not happen again!
Thanks for your interest, regards JH
 
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Don't forget, the drone is going to calculate battery needed to get back to home point, not what's needed to get to where you happen to be. By default, home point is set to where you took off, which you, as well as the drone, later moved 150m away. 19% sounds about right for low battery RTH to trigger at that distance. You can reset the home point to the current AC position during flight. You can also set HP to your position if the app recognizes your device's GPS.

If you hear "beep-beep, beep-beep, beep-beep" from the RC, it's in RTH mode.
Not to be confused with a rapid "beep-beep-beep" related to a nearby obstacle being detected.

The AC will usually want to critical land once SOC reaches 10%, higher SOC if at very high altitudes. Just as you can fight RTH, you can also fight critical land, even when SOC has reached 0. At 0 you can probably fly for 2 more minutes before it drops. Billy Kyle found this out the hard way.
 
If you reach for the AC while it's hovering or descending, it will see that as a sudden obstacle below it and rise up away from you. Leave your hand underneath, then use throttle to descend onto your hand.
 
If you reach for the AC while it's hovering or descending, it will see that as a sudden obstacle below it and rise up away from you.
His drone was in RTH and attempting to climb to RTH height.
He did not cancel that so the drone kept trying to climb.
 
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