Hi guys, I would like your expert opinions on my flight data.
Long story short, I placed the drone on the ground, next to an artificial lake. I hit the take off button and the drone went in autopilot mode and flew at maximum speed towards the water which was several feet below the take off point and crashed into the water. All this happened while the drone was in VLOS and I tried to issue some commands to stop it but it did not listen to me. The drone from the records seems to switch to ATTI milliseconds before the crash or potentially already crashed. Maybe there was a slight chance to save it if I had held in up position the left joystick when ATTI kicked in which I understand this is manual control of the drone.
Post crash, I could not recover the drone, I have filled a flyaway report with DJI and waiting on them to come back to me with the assessment. What’s your take, user error or malfunction? Did I do something wrong here? I guess flying with poor GPS signal? But I only wanted it to hover like it normally does when GPS signal is poor and I wait until the GPS signal improves. However this time things didn’t play out. Thanks.
Normally it is not a good idea to start flying before you get a “Home point updated” message.
In any way, you should be able to see what happened in the flight record. Start the RC2 (not necessary to connect any drone), select My profile and on that screen (down left somewhere) you should see “More…”. Click on this, and you will get a list of all the flight records. Clicking on the one where it failed, you will see a map and playback about what happened (including any messages).
What you probably also should do is to post this on the DJI Forum (https://forum.dji.com/). Then DJI probably will give you instruction have to send required files to them.
Thanks for the answer! I have already opened a flyaway ticket with DJI and waiting for them to reply. I understand your reply tilts more towards user error then. Thanks for the input
It does not have to be a user error (even if flying off before the Home point is updated really isn’t a good idea), but looking at the flight record may give you some answers. Look at this guide: How to Check Flight Records.
I have checked the flight record and uploaded on the tool of this website too if someone experienced can have a look at it and give me their view. The tool on this website provides a lot more details about the flight records than looking just within the DJI fly app. The flight lasts about 10 seconds. Essentially I hit the take off button and auto pilot takes over and dives into water about 50 meters below take off.
The aircraft automatically changes to Attitude (ATTI) mode when the Vision Systems are unavailable or disabled and when the GNSS signal is weak or the compass experiences interference. This means that you have to fly manually and RTH will not work (i.e. not a good idea to take off).
It is quite easy to see that you have an issue with the GPS signals. To understand the increase in speed, but if you look at the flight log via the RC2, you should be able to see what kind of stick input that has been made. From what I can se the speed gradually increases and reaches 69mph (that is very fast).
I am also unfamiliar with any Autopilot other that what the drone does when returning to home. The only thing I can think of for this to happen is if the forward stick is pushed forward and the cruise control accidentally has been engaged. What flight mode was it in?
Have you tried looking in the RC2 flight log viewer (as it provides more information than you will see on the Flight log viewer you link to.
As said earlier; try to look as described in the guide I provided earlier in the post.
PS. I now realise that the link I sent you regarding how to view your flight log on the RC2 has been blocked by the community because they think it is spam. Why, I really do not know, because it is absolutely relevant.
No it was not simple cruise control, highly unlikely, I pressed the button for the drone to take off with 9 satellites count. In the 10 seconds that it flew I issued a couple upward commands using the left stick and the drone ignored them. The drone entered ATTI mode as seen in the flight logs for a few milliseconds before or after the drone already had been in the way, even if I could react within the span of 3-4 milliseconds I doubt it would have been physically possible for the drone to stop a dive at almost 70 mph speed. In my experience when I hit the take off button it never did this even if there were 0 satellites, the drone would just hover stably and let you know that you can can’t fly over 30m in height. I find it very strange that the drone did this…
Did you do a screen recording? I find this useful and do this always before taking off. It provides even more information. But regarding this, I did experience very strange behaviour from the controller when I used a micro SD card that clearly was not compatible (even no message were given on the screen - it just froze, and the controllers were just randomly working and return to home were initiated automatically).
Looking at you altitude, it also seems like you were descending quite a lot. At the end it is perceived that the drone is -154,5ft below the takeoff point. This may also be the cause of the signal loss, and once again both the RC2 flight log viewer and if possible a screen recording could give some answers to this.
Thanks again for the reply. Unfortunately no screen recording, everything was very sudden and I barely had any leeway to do anything. I have on the RC2 a sandisk extreme pro 128gb and on the drone I had a sandisk extreme pro 512gb. I was standing on a ledge of shorts next to an artificial lake that was below me. I had constant visual line of sight to the drone until the last moment when it crashed.
I guess that whatever cause, it is a lesson learned that you should not take off before sufficient satellites has been registered and the Home point has been updated, because then you can at least press Return to Home at get it beck to a known area. Did you try to press the pause button? This should brake the drone and make it hover in the air.
PS. To make sure of a Precision landing (coming back to the exact spot), you should raise your drone above 7 meters after the Home point has been registered. This will give the two downwards cameras the required time to record the takeoff spot.
Hope you get a new drone back soon.
PPS. It is wise to start a screen recording before taking off. This has given me a lot of valuable information in cases where problems occurred.
thank you, I guess this is a lesson learned. No I did not hit the pause button even though I had the same thought afterwards… but too late, there was very little time to react.
After having had some mishaps myself, I do training on emergency moved in a controllable area. This has already helped me some, and I hope more training will get me better prepared. Perhaps something to consider?
Sure this makes sense. It’s hard to really deal with this unless you experience it once. Now I know that I expect during certain actions a corresponding behaviour by the drone, if the drone does anything unexpected have to immediately try to hit the pause button.
I have tested the pause button if different scenarios, and especially in Sports mode, because by just letting go of the forward stick, it brakes quite well, but if you press the pause button, even when you hold the stick, you will get a message saying “Aircraft braking”, and it really stops fast. If you are on any automated task it will also brake (and hover). It is a very good thing to have the finger close to the pause button if you are doing risky flying. I am also testing the emergency propeller stop to see how it works in a controlled area and something soft to land on (because I could have had a use for it when I crashed into some bushes a while ago - luckily no damage).
It’s possible I suppose, but not a common problem. Behavior like this is more often caused by doing things like powering up a drone inside a car or taking off from a concrete sidewalk embedded with rebar.
Thank you! I don’t recall doing something like that, but I will definitely keep this in mind! There’s so many new things I learned after crashing it… there’s lots of things you are not supposed to do but they are not obvious, such as this one.
