Altitude drop cause?

[itzamna]

During a flight the other day my DJI GO 4 app crashed, which isn't unusual. I was unable to get it to connect back up though but I still had RC connection. I sat there for a minute or two trying to get it to work while letting the Mavic hover. I decided I was going to try and bring it back to me just using the altitude and distance readouts on the RC.

Here is the csv of the log file. The descent starts around line 11135 or so.
Dropbox - FLY026.csv

I don't remember ever pulling on the stick to lower the altitude. That's not to say that I didn't, I just don't remember doing it. I look down and I'm losing altitude at a steady pace suddenly. I do know at the point that I noticed the descent I wasn't pulling it down and it was continuing to drop with no input from me. Pushing up on the stick did not stop the descent. It seemed like it was in landing mode. Thankfully, I've lurked here enough to know to toggle sport mode and I was able to stop it. I thought the new firmware was supposed to allow an up input to cancel this, but it did not. Eventually I just did a RTH and all was well.

I've gone through the log, but I'm no expert at reading. There are no flight actions listed during the descent but you can clearly see it. I'm not sure where to see my input on the log honestly. There is nothing from VPS at that point so it doesn't seem like that is an issue either. Just wondering if someone can tell me what happened. This did prompt me to finally break down and buy an iPad mini because I'm frankly tired of the constant crashed on Android with the DJI software.

 

[Cyberpower678]

I just analyzed your flight log. Your throttle was all the way down. When you ascended, your throttle was all the way up. I see no toggling sport mode on your drone, and I see no malfunction. Your drone was not in forced landing mode. Sorry. Your drone is operating normally.

 

[itzamna]

I had sport mode locked out at the time so it would not actually go into sport mode either way, but I definitely did toggle the switch on and off. I don't doubt that I could of been telling it to go down at first, but I know for sure it was descending with no input from me at one point and that pulling up wasn't doing anything. I got no reaction until I toggled the switch.

 

[Cyberpower678]

I had sport mode locked out at the time so it would not actually go into sport mode either way, but I definitely did toggle the switch on and off. I don't doubt that I could of been telling it to go down at first, but I know for sure it was descending with no input from me at one point and that pulling up wasn't doing anything. I got no reaction until I toggled the switch.

Not according to the flight logs. It was dropping the moment your throttle stick was pulled and stopped doing so when you let go. Then you immediately pushed it down again and then continued to descend. Then it just floated for a bit at the new altitude until pushed the throttle back up, and the drone then climbed. You then initiated RTH, which executed correctly and then landed back at the home point. It's all very clear in the CSV.

 

[DV Mavic]

What mode is your controller in?

 

[itzamna]

Is it possible that the remote was telling me it was descending when it was not? A delay in the readouts perhaps?

I looked through the log myself some more and I see that I did switch to sport mode and back out after the drone shows me pushing back up on the stick and gaining altitude. This is leading me to think there was a delay for some reason with the remote and the altitude it was displaying. The drone was aligned facing away from me when the app crashed and wouldn't reconnect. My plan was to just come backwards. I'm wondering if I started pulling down on the wrong stick after being frustrated with the app, and all of the inputs it clearly shows after that, but was not seeing what currently was happening in the readouts. Then finally recognizing the drop I try to push up, but due to a delay, I'm still seeing a drop and then tried the sport mode toggle, thinking it was a VPS type issue going into forced landing. I gained 12 m or so before it shows me flipping the sport switch, then the much longer ascent afterwards.

So I guess to make it short, the drone shows Down, Short Up, Toggle Sport On/Off, Longer Ascent.
I saw Down, Short Up input that did nothing seemingly, Toggle Sport On/Off, Ascent.

Thanks for your help by the way. I know I commit plenty of pilot errors with both quads and planes. The descent probably was my error. I just know at one point I was being shown a descent happening without input and it didn't stop until I toggled the switch.

What mode is your controller in?

Mode 2.

 

[Cyberpower678]

Is it possible that the remote was telling me it was descending when it was not? A delay in the readouts perhaps?

I looked through the log myself some more and I see that I did switch to sport mode and back out after the drone shows me pushing back up on the stick and gaining altitude. This is leading me to think there was a delay for some reason with the remote and the altitude it was displaying. The drone was aligned facing away from me when the app crashed and wouldn't reconnect. My plan was to just come backwards. I'm wondering if I started pulling down on the wrong stick after being frustrated with the app, and all of the inputs it clearly shows after that, but was not seeing what currently was happening in the readouts. Then finally recognizing the drop I try to push up, but due to a delay, I'm still seeing a drop and then tried the sport mode toggle, thinking it was a VPS type issue going into forced landing. I gained 12 m or so before it shows me flipping the sport switch, then the much longer ascent afterwards.

So I guess to make it short, the drone shows Down, Short Up, Toggle Sport On/Off, Longer Ascent.
I saw Down, Short Up input that did nothing seemingly, Toggle Sport On/Off, Ascent.

Thanks for your help by the way. I know I commit plenty of pilot errors with both quads and planes. The descent probably was my error. I just know at one point I was being shown a descent happening without input and it didn't stop until I toggled the switch.



Mode 2.

I don't see sports being engaged at all in the log and the only descent I saw was from user input.

 

[itzamna]

I don't see sports being engaged at all in the log and the only descent I saw was from user input.

Line 12095 shows the flip to Sport for me, then switches back to P at Line 12107. This is after the first short ascent. I think that you are right that the descent was user input and that I screwed up, but I think I was seeing a delay in the altitude readout on the RC. The drone's logs are showing the same actions I thought I performed when I recognized the descent. The logs also show it reacting to my initial up input by ascending where I was still being shown a descent. The actions are the same, the timing is off which is why I think there was a delay in the readouts.

I have to say that I've flown this thing a lot with no other problems outside of the Android issues.

 

[Cyberpower678]

Line 12095 shows the flip to Sport for me, then switches back to P at Line 12107. This is after the first short ascent. I think that you are right that the descent was user input and that I screwed up, but I think I was seeing a delay in the altitude readout on the RC. The drone's logs are showing the same actions I thought I performed when I recognized the descent. The logs also show it reacting to my initial up input by ascending where I was still being shown a descent. The actions are the same, the timing is off which is why I think there was a delay in the readouts.

I have to say that I've flown this thing a lot with no other problems outside of the Android issues.

Yea, sorry I was looking at the wrong signal. I was looking at the flight modes, and not the toggle switch. I see the switch too, but I'm still inclined to believe this was from user input, and your theory about latency may be true.