I just posted how I had no hard landings or crashes and now last night had my first crash. Posting the details in case it helps any other new flyers.

I launched the mini 3 off my deck as I have done so many times before. By the time I brought it back it started to get dark. Add it got closer to the landing it displayed the low light error and the obstacle avoidance was disabled. This is where things went wrong. It started drifting forward and went right into my house. To make matters worse it didn't shut down until it bounced off the deck a few times with the motors turning. I would have thought they shut down immediately.

I'm sure this was just a noob mistake. Bringing it back in the dark was probably a mistake I should have turned the lights on.

Thanks for letting us knowhow that situation works out, much appreciated and sorry you had to go through it 1st, hope there isnt much damage

That sucks, but has happened to all of us.  If you are not crashing, you are not flying.

TonyPHX Posted at 8-29 06:28
That sucks, but has happened to all of us.  If you are not crashing, you are not flying.

Exactly! The drone seemed to take it well. I was a little surprised it kept spinning like it did. I think that's what caused most of the damage. It didn't hit the house hard at all but then went nuts on the ground lol. Minor scrapes is all I can see and a quick test flight seems like its ok. Taking it out soon to check a few other things.

I'm going to try and review the logs too (haven't ever done that yet). Just to see what really happened to avoid this mistake again!

Eveezy Posted at 8-29 07:10
Exactly! The drone seemed to take it well. I was a little surprised it kept spinning like it did. I think that's what caused most of the damage. It didn't hit the house hard at all but then went nuts on the ground lol. Minor scrapes is all I can see and a quick test flight seems like its ok. Taking it out soon to check a few other things.

I'm going to try and review the logs too (haven't ever done that yet). Just to see what really happened to avoid this mistake again!

It lost vision,  and drifted, and the OA sensors were of no use due to low lighting.  I won't blame the pilot...  : )

After looking at the flight on the RC the drone lost GPS just before the crash. GPS lost, then it drifted right into the house. So I feel a little better that it wasn't just my inexperienced flying. I guess that would explain why it suddenly started drifting in all directions.

I'm curious why it would have lost GPS, assuming you've had GPS lock before launching from your deck all previous times.  I wouldn't think darkness would have anything to do with losing GPS. Losing GPS lock would explain why it drifted into the house, though. Sorry for it happening to you.  

K9JDN Posted at 8-29 08:11
I'm curious why it would have lost GPS, assuming you've had GPS lock before launching from your deck all previous times.  I wouldn't think darkness would have anything to do with losing GPS. Losing GPS lock would explain why it drifted into the house, though. Sorry for it happening to you.

Thanks

Yes, I had GPS lock 20-23 sats. I always wait until it has gps before taking off. Right when landing it went from 23 to 6 when the GPS was lost at which point the crash happened.

Actually, I would draw something else from this, it isn't wise to approach a landing point with OA on, it can create problems.
Assuming the approach was forwards the OA should, in daylight, detect the house and any other obstacles in its flight path, incuding possibly you.
As far as I remember DJI switch OA off in the landing/descent phase of RTH etc. with the only drone that I have that has OA, not a Mini 3.

That said, the absence of OA is not what lead to the drifting, the darkness must have been sufficient to render the downward looking VPS sensors ineffective or the surface of the deck is so uniform that, in the lighting conditions, the VPS could not recognise a movement. Either way I am wondering why you didn't give commands to counter the drifting?

Also, if close to a vertical surface (within inches), there is an apparent tendency for drone to 'suck into' that surface, possibly because of the fast moving down draught creating a 'low pressure' region between the drone and the wall.
Also, GPS is unaffected by lighting conditions, which probably means you take off with insufficient GPS and that the home point may be established somewhere else, that being wherever the drone first gets sufficient GPS to establish one. If correct then the drone has previously behaved well during your take offs etc due to correctly working VPS and an errant homepoint could cause problems in an RTH.

Sean-bumble-bee Posted at 8-29 08:32
Actually, I would draw something else from this, it isn't wise to approach a landing point with OA on, it can create problems.
Assuming the approach was forwards the OA should, in daylight, detect the house and any other obstacles in its flight path, incuding possibly you.
As far as I remember DJI switch OA off in the landing/descent phase of RTH etc. with the only drone that I have that has OA, not a Mini 3.

I can see that it wasn't clear in my original post. So just as a follow up to your suggestions and observations...

I did not in use RTH, I always land manually (habit from landing launching from my boat). Also I don't think anyone suggested GPS was lost due to low light. Low light is what caused OA to be disabled. And finally, I did try to correct it but I wasn't good enough to counter the "drift". Honestly, calling a drift is a little misleading. It was fast drifting movements. Hindsight, I should have just held down and forced it to land. Rather than trying to correct the drift.

With all that said I'm still curious why it suddenly lost GPS.

*Edit* forgot to add that I am not trying to sound defensive. Just clarifying in case it helps anyone else.

TonyPHX Posted at 8-29 06:28
That sucks, but has happened to all of us.  If you are not crashing, you are not flying.

I like that Tony.

I think you misunderstood my post.

I did not, and do not think, you used RTH. I cited RTH as a demonstration of the fact that DJI disable OA during certain automated procedures i.e. landing. They do this for a reason, it can become a liability during landing as there may be multiple 'obstacles' within OA's 'sight' and detection of them can cause problems.

That I am aware of I did not suggest that anyone suggested that darkness disables GPS, for clarity, it does not. I have flown a drone in darkness with fully functional GPS positioning and normal numbers of satellite counts.

Obviously low light disables OA......but it also disables VPS  and VPS IS NOT OA, it is something completely different.
It is, if you like, "optical position holding" and, when lighting condition are suitable and the drone is low enough, VPS will, over suitable surfaces, hold the drone's position FAR more accurately than GPS.
Our drones' position holding accuracy when due to solely GPS is measured in feet or metres, when VPS is available it is within inches or cm. Try it in a well lit room under a GPS opaque ceiling/roof.

However, I was attempting to imply that the loss of GPS may have been due to the drone's proximity to the house and or any nearby trees etc..
If so then it is possible that you have, unknowingly, been launching the drone with insufficient GPS to establish a home point at the take off point. That, in itself, is not necessarily unwise, I do it all the time because my take off points are often masked from GPS by trees etc. but you do need to know how to compensate for that and or how to reset the home point to somewhere appropriate. Otherwise there can be all sorts of complications later in the flight since the home point will be set to wherever the drone was when if first got sufficent GPS. Such a home point could lead to the loss of the drone and has done so.
I would suggest that you check your old flight logs to see if this is the case. You can do that by replaying flights in the app or on websites such as https://www.phantomhelp.com/logviewer/upload/
or Airdata.

Also be aware that, without GPS and VPS the drone has no position holding capability NOR will it brake to halt any horizontal movement when the sticks are centred. Also it will be blown about by any wind. Any and all pilot's control of movement will be through manual input to the controller alone i.e stick movements.

Sean-bumble-bee Posted at 8-29 10:33
I think you misunderstood my post.

I did not, and do not think, you used RTH. I cited RTH as a demonstration of the fact that DJI disable OA during certain automated procedures i.e. landing. They do this for a reason, it can become a liability during landing as there may be multiple 'obstacles' within OA's 'sight' and detection of them can cause problems.

Ya I think we both had some misunderstanding. It happens, no worries.

I think you're right about the proximity to the house causing GPS loss. I take off and land from this spot because it's clear of trees. I always wait for gps lock and home point update before taking off. I've landed in this spot a bunch of times but as you suggested I'll review the other logs to see if there is ever gps loss that I just never noticed. I think I'll change my landing spot to avoid this in the future. There is only about 10ft clearance from landing spot to house and it's a tall house so maybe conditions where just right and it caused the GPS loss. Ex I take off facing east but land facing west... I'm sure all that can play a role in GPS signal.

Thanks again for the detailed help

Hi there. Thank you for reaching out and we're sorry for the unpleasant experience. In this kind of situation, I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support . Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. Thank you for your kind and understanding.

Ex I take off facing east but land facing west... I'm sure all that can play a role in GPS signal. East vs west should have no affect on GPS reception, as far as I am aware DJI puts the GPS receiver on the top of the relevant circuit board and just under the top plastic 'lid' of the drone.

Sean-bumble-bee Posted at 8-29 10:42
Also be aware that, without GPS and VPS the drone has no position holding capability NOR will it brake to halt any horizontal movement when the sticks are centred. Also it will be blown about by any wind. Any and all pilot's control of movement will be through manual input to the controller alone i.e stick movements.

Sorry for the dumb question... I finally exported my logs. If VPS Altitude is showing a value then it wasn't yet disabled right?

It is far more detailed to review the log for me on Phantom help. I can see in the log that the VPS Alt. always had a value up until the crash and probably can confirm that the crash was a result of GPS losing signal + inexperienced pilot (me). Just before the crash I can see I hit down (to land) when I should have hit back which is just inexperience for sure.
Lesson leared to pick a spot with more clearance and practice stick movement more to avoid "panic" mistakes. It still doesn't explain why GSP was suddenly lost. I will start a support ticket to see if there is an issue with the drone itself or if it was just interference.

I would share the log on here, but since it was a flight at my house I just feel odd sharing that info. I'm weird like that I guess...

Thanks again for helping me understand the conditions and learn from this crash.

The VPS altimeter uses, I think, its own 'light' source, infra red, and from memory works in darkness. The position holding portion of VPS uses visible light.
I understand not wanting to post the logs but if you do not wish to make the lat' and long' public you could make a copy of the PH csv then remove the contents of the Latitude  & Longitude columns ( at least two sets), but leave the columns in place. Perhaps also remove the contents of the serial number columns and drone name columns but again leave the actual columns in place.
Then upload the edited csv to a hosting site such as dropbox, make the file public and post a link here. One of the gurus may take a look.