Forced auto-land crash...

[pjd900]

I've had this same problem 4 times since receiving a Care Refreshed Mavic a few weeks ago. The VPS sonar sensors will randomly show an altitude of only a couple of feet when the craft might be hundreds of feet in the air. Water has nothing to do with it. If you happen to be descending with full stick down when this problem occurs, it will send the Mavic into a forced auto landing which cannot be cancelled with full stick up.

It has happened both in GPS mode, as well as SPORT mode. I have been able to stop the forced landing by toggling between modes, but not every time.

It hasn't happened in a while, so I'm keeping my fingers crossed. I really don't want to send it back again to DJI repair. Getting this replacement back from Care Refresh took FIVE weeks...

 

[BorisTheSpider]

Wow now that sucks - I hadn't considered the possibility of random VPS errors over land. It seems the case for rolling back to the .400 firmware is getting stronger.

 

[Mavicsailor]

I haven't tried it since I'm not able to reproduce a forced landing when not near the ground. In some other threads, people were saying a stick up does not cancel forced landing mode when using the current Mavic firmware. A few other people said it could be cancelled by switching to sport mode. I don't think any of those people were testing those cancellation methods when high up in the sky (just when close to the ground).

The best advice I can give you is to turn off VPS when flying over water. Or never move the throttle to the full down position when flying over water. Either will prevent forced landing mode from being accidentally initiated.

At least for canceling the landing at .5 meters where it asks for a confirmation, turning "landing protection" off, then using up throttle works to abort a landing, as well as quickly flipping between sport and gps mode, or gps to sport. With landing protection on, with the lastest firmware, you can't abort the landing once you confirm it at .5 meters. When turn off landing protection, it just comes straight down and still makes a smooth landing. Actually, kind of nice. For those daring pilots that want to hand catch (not recommended), turning landing protection off eliminates the AC wanting to flying up when you put your hand under it to catch it. The question remains if the Mavic handles a forced landing the same as it handles landing with confirmation.

For those that want to try landing on a boat, turning off "landing protection" definitely will be safer as you have control all the way down, but still get a soft landing.

 

[msinger]

So, what exactly IS the correct response? Flip into Sport mode?

I'm not sure. As I noted above, some people said flipping to sport mode cancels forced landing mode when the Mavic is actually less than 0.5 meters from the ground. Some testing will need to be done to see if the same can be done when higher up in the air.

 

[msinger]

The VPS sonar sensors will randomly show an altitude of only a couple of feet when the craft might be hundreds of feet in the air. Water has nothing to do with it.

While water might not have anything to do with it, almost everyone who has posted about this issue here was flying over water at the time.

 

[msinger]

I did some testing this afternoon to see what would happen when forced landing mode was engaged either near the ground or high up in the air. To recreate the latter, I taped a ribbon to the front and back of my Mavic at about 3 inches from the bottom of the Mavic. That caused the VPS to constantly show a reading that was less than 0.5 meters.

Note: I'm running firmware version 01.03.0500.

Here's what happened when the "Visual Navigation Settings" --> "Landing Protection" setting was enabled:

• When the throttle was moved to the full down position, forced landing mode was initiated and my Mavic started to auto land.
• Moving the throttle to the full up position did not cancel the auto landing.
• Moving the sport mode switch from off to on OR on to off cancelled the auto landing.
• Whenever the VPS altitude was showing less than 0.5 meters at the bottom of DJI GO, my Mavic would slowly ascend on its own. This would continue until I either initiated a forced landing again (by moving the throttle to the full down position) or disabled the "Landing Protection" setting.

Note: I observed the same behavior no matter how high my Mavic was from the ground.

Here's what happened after removing the ribbon from the bottom of my Mavic:

• When the throttle was moved to the full down position, forced landing mode was only initiated when my Mavic was close to the ground.
• Moving the throttle to the full up position did not cancel the auto landing.
• Moving the sport mode switch from off to on OR on to off cancelled the auto landing.

In conclusion, I found "Landing Protection" is the only setting that needs to be disabled in order to prevent forced landing from being accidentally initiated when high up in the air. It's okay to keep the "Enable Vision Positioning" setting enabled.

 

[rtw07]

That's some really good info msinger! Seems like they could do a couple things to help with this... most importantly, allowing up stick to cancel the landing like in previous firmware. It also seems there should be some sort of safe guard that disables the VPS when your altitude is over a certain height. Why does the Mavic prioritise the VPS data over the altitude data?

I'm hoping DJI will honor the warranty on my Mavic. I haven't tried flying since the crash so I don't if there are any internal issues from the crash. Don't think I should be held responsible for a faulty sensor reading and an unintuitive method of correcting the problem.

EDIT: Another thought... what if users had flight mode switching disabled, which I believe is default. You would have no way of stopping the autolanding without quickly digging into the settings and turning flight mode switching back on.

 

[rydfree]

Awesome , it works as expected !

 

[msinger]

Why does the Mavic prioritise the VPS data over the altitude data?

The VPS data should always be most accurate when the Mavic is close to the ground. Furthermore, once the Mavic flies away from the home point, the altitude will no longer be an accurate measurement from the ground up if the ground elevation changes. The Mavic has no way of knowing where the ground is located unless it's near the ground and the VPS is detecting an accurate measurement.

 

[Wacker2611]

So, in summary then, the only we thing we need to do is disable landing protection (which is a pretty non useful feature anyway)?

 

[msinger]

You got it.

 

[pjd900]

Thanks for your testing info, msinger.

For those of us that are experiencing these random forced landings while flying at altitude, I wonder what's causing the problem? Software glitch or bad sonar hardware?

DJI says I have to send the Mavic back for testing...I'm holding out to see if the problem resolves itself. Customer service said repair will not look at my flight data without having the Mavic in their hands.

 

[pjd900]

So, in summary then, the only we thing we need to do is disable landing protection (which is a pretty non useful feature anyway)?

Just be aware that you can slam into the ground if you're coming in too hot for a landing. the usual automatic slow down just before touchdown will be disabled.

 

[Wacker2611]

Just be aware that you can slam into the ground if you're coming in too hot for a landing. the usual automatic slow down just before touchdown will be disabled.

Fine by me, I'm used to a P3A which didn't have landing protection. Added to the fact that I hand catch 90% of the time. I should have turned it off from the start, I'm kicking myself!

 

[Mavicsailor]

Just be aware that you can slam into the ground if you're coming in too hot for a landing. the usual automatic slow down just before touchdown will be disabled.

Actually, there should be no concerns about a hard landing when "landing protection" is disabled. I've tested this with full throttle down from 50 feet, and when the AC approaches the ground it slows down to make a perfect soft landing. It just doesn't stop at .5 meters asking for landing confirmation.

Having landed multiple times now with "landing protection" off, I wish I knew about this earlier. I feel like I have much more control when landing. I can even take off again immediately after touching the ground before the props stop.

I want to thank BudWalker for first pointing out the advantages of turning off landing protection as it concerned a work around for the latest FW, and the inability to stop a forced landing with full throttle up.

 

[Strafe1]

Just be aware that you can slam into the ground if you're coming in too hot for a landing. the usual automatic slow down just before touchdown will be disabled.

Mavicsailor is correct. I have also tested this out. The Mavic will slow down for a nice soft landing regardless of descending speed, it just won't make a pause at 0.5 meters.

 

[Strafe1]

I did some testing this afternoon to see what would happen when forced landing mode was engaged either near the ground or high up in the air. To recreate the latter, I taped a ribbon to the front and back of my Mavic at about 3 inches from the bottom of the Mavic. That caused the VPS to constantly show a reading that was less than 0.5 meters.

Note: I'm running firmware version 01.03.0500.

Here's what happened when the "Visual Navigation Settings" --> "Landing Protection" setting was enabled:

• When the throttle was moved to the full down position, forced landing mode was initiated and my Mavic started to auto land.
• Moving the throttle to the full up position did not cancel the auto landing.
• Moving the sport mode switch from off to on OR on to off cancelled the auto landing.
• Whenever the VPS altitude was showing less than 0.5 meters at the bottom of DJI GO, my Mavic would slowly ascend on its own. This would continue until I either initiated a forced landing again (by moving the throttle to the full down position) or disabled the "Landing Protection" setting.

Note: I observed the same behavior no matter how high my Mavic was from the ground.

Here's what happened after removing the ribbon from the bottom of my Mavic:

• When the throttle was moved to the full down position, forced landing mode was only initiated when my Mavic was close to the ground.
• Moving the throttle to the full up position did not cancel the auto landing.
• Moving the sport mode switch from off to on OR on to off cancelled the auto landing.

In conclusion, I found "Landing Protection" is the only setting that needs to be disabled in order to prevent forced landing from being accidentally initiated when high up in the air. It's okay to keep the "Enable Vision Positioning" setting enabled.

Thank your for the testing! This is terrific information.

 

[MacIak]

I did some testing this afternoon to see what would happen when forced landing mode was engaged either near the ground or high up in the air. To recreate the latter, I taped a ribbon to the front and back of my Mavic at about 3 inches from the bottom of the Mavic. That caused the VPS to constantly show a reading that was less than 0.5 meters.
.

Thank you

 

[Davidss]

Yes, thank you to MSinger / MavicHelp from me as well.
It was good of you to come up with the 'ribbon method' for misleading the VPS while at altitude.

Regards.

 

[mfarris2]

Good to know and VERY TRUE -- there is no reason why left stick up shouldn't stop the landing. Odd that with so many settings in the remote, there isn't a way to manually change this.

Also, as the weather gets warmer I'm going to be doing a lot more flying from our boat, and the takeoff/landing area on the rear deck is pretty small. Good to know that once I start that "forced landing" procedure, I am committed to the landing spot. I mistakenly thought that if the landing starts to go wrong, I could throttle up and attempt a do-over. I guess not!

This is an issue I addressed a few weeks ago. I too was flying and every time,....I used my left stick and wanted to lower my drone,...it would go into landing,....full or slight down stick. I posted my flight txt file and it was then that we discovered it was due to the new firmware update.
I have flown since,...but have not encountered that issue again. The first time I started over water,....but had the same issue when over land as well. Since it has always been strictly over land.
Several other people chimed in and stated they too were now suffering the same issue. Others stated that when they were in that situation,....they could cancel the forced landing by switching from Sport to normal or normal to sport mode.
At this point I wish I could go back in time. I'd still be flying my P3P (sold to buy the Mavic) and DJI could keep their Mavic!