Toilet Bowl Effect- Mavic Pro

[BrucenYvette]

Greetings: I had an "unusual happening" and wondered if anyone might have some insight.

FYI, I'm flying a pre-Sept 2017 manufactured Mavic Pro, firmware V.01.04.0400, with a Doogee Mix android 7, 4GB/64GB phone.

While flying my Mavic Pro I had two occasions within 2 days where the aircraft went into the "toilet-bowl-effect".

In both cases, I had completed 15-to-20 minute flights without issue; I was in RTH-Mode; I had minimum 25% battery remaining when aircraft arrived "home" directly overhead. It was at this point when things went haywire.

While directly overhead at approximately 150 feet, instead of initiating the landing sequence, the aircraft lost GPS-lock and dropped into ATTI-mode. The aircraft then went into a slowly increasing circular pattern doing 3 or 4 lazy circles at the same time drifting with the wind. In both cases I was able to get control of the aircraft and land safely.

As I have been researching, I have found that this can occur at the BEGINNING of a flight if there is a magnetic influence effecting the compass at launch which can give a false "OK" between IMU and compass that allows GPS-lock. But, according to one source (

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) , typically when the aircraft lifts away from the magnetic influence, the compass correction then conflicts with the IMU which breaks GPS-lock at the BEGINNING of the flight within 20 feet or so altitude and sends the aircraft into TBE.

I don't understand why, at the end of a normal flight at the point of having returned home and about to engage landing sequence, the aircraft suddenly goes "rogue".

 

[sar104]

That is certainly less common - the explanation that you saw is the usual cause of this effect. It also cannot, theoretically, occur in ATTI mode since, in that mode, all the FC is doing is holding the aircraft level. The toilet-bowl effect, as generally observed, is a direct result of the aircraft attempting to navigate or hold position when the compass and IMU disagree by approximately 90°.

The answer will probably be found in the logs for that flight - ideally both the mobile device txt log and DAT file.

TXT log: DJI Flight Log Viewer | Phantom Help

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[Starz]

Watching. Always some knowledge to gain with these kinds of scenarios.

 

[Former Member]

I feel for you, OP, and Im glad you got it down safely. The Toilet Bowl Effect is one of the most terrifying phenomena to happen because it results in loss of control, regardless of your stick inputs. If a pilot has alot of experience, sometimes they can be patient, wait for a window the drone is responding, and manage to land it.

I have had it happen during a flight several times, and it took all of my skill to get it back down again.

You dodged a bullet on this one.

 

[BrucenYvette]

That is certainly less common - the explanation that you saw is the usual cause of this effect. It also cannot, theoretically, occur in ATTI mode since, in that mode, all the FC is doing is holding the aircraft level. The toilet-bowl effect, as generally observed, is a direct result of the aircraft attempting to navigate or hold position when the compass and IMU disagree by approximately 90°.

The answer will probably be found in the logs for that flight - ideally both the mobile device txt log and DAT file.

TXT log: DJI Flight Log Viewer | Phantom Help

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

I was flying Litchi App and have flight data in Airdata UAV. Not sure how to get that to you. It's a very interesting "read".

 

[sar104]

I was flying Litchi App and have flight data in Airdata UAV. Not sure how to get that to you. It's a very interesting "read".

Click the "Share" button on the AirData page:


The deselect all ("None") and enable at least the data shown below:




The post the unique sharing link back here.

 

[BrucenYvette]

Appreciate the help and look. Here's the link:

 

[sar104]

Appreciate the help and look. Here's the link:

Sorry - forgot to include that you also need to check the General/Overview box on the right side of that sharing options.

 

[BrucenYvette]

Here tiz with General/Overview:

 

[BrucenYvette]

I feel for you, OP, and Im glad you got it down safely. The Toilet Bowl Effect is one of the most terrifying phenomena to happen because it results in loss of control, regardless of your stick inputs. If a pilot has alot of experience, sometimes they can be patient, wait for a window the drone is responding, and manage to land it.

I have had it happen during a flight several times, and it took all of my skill to get it back down again.

You dodged a bullet on this one.

Yeah...was VERY lucky. The somewhat out-of-control landing was nothing short of spectacular. Was in forced landing mode. It was about 3 feet over the road when I "forced" it across the road to land in the yard!

 

[Former Member]

Yeah...was VERY lucky. The somewhat out-of-control landing was nothing short of spectacular. Was in forced landing mode. It was about 3 feet over the road when I "forced" it across the road to land in the yard!

Quick thinking and reaction time probably saved you some serious money.

 

[BudWalker]

Greetings: I had an "unusual happening" and wondered if anyone might have some insight.

FYI, I'm flying a pre-Sept 2017 manufactured Mavic Pro, firmware V.01.04.0400, with a Doogee Mix android 7, 4GB/64GB phone.

While flying my Mavic Pro I had two occasions within 2 days where the aircraft went into the "toilet-bowl-effect".

In both cases, I had completed 15-to-20 minute flights without issue; I was in RTH-Mode; I had minimum 25% battery remaining when aircraft arrived "home" directly overhead. It was at this point when things went haywire.

While directly overhead at approximately 150 feet, instead of initiating the landing sequence, the aircraft lost GPS-lock and dropped into ATTI-mode. The aircraft then went into a slowly increasing circular pattern doing 3 or 4 lazy circles at the same time drifting with the wind. In both cases I was able to get control of the aircraft and land safely.

As I have been researching, I have found that this can occur at the BEGINNING of a flight if there is a magnetic influence effecting the compass at launch which can give a false "OK" between IMU and compass that allows GPS-lock. But, according to one source (

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) , typically when the aircraft lifts away from the magnetic influence, the compass correction then conflicts with the IMU which breaks GPS-lock at the BEGINNING of the flight within 20 feet or so altitude and sends the aircraft into TBE.

I don't understand why, at the end of a normal flight at the point of having returned home and about to engage landing sequence, the aircraft suddenly goes "rogue".

For this one we're going to need the .DAT from the MP. Take a look here to see how to retrieve it. It'll be large so you'll need to use Dropbox, GoogleDrive or similar and post a link.

What's the basis for saying "the aircraft lost GPS-lock and dropped into ATTI-mode"?

@sar104

 

[sar104]

For this one we're going to need the .DAT from the MP. Take a look here to see how to retrieve it. It'll be large so you'll need to use Dropbox, GoogleDrive or similar and post a link.

What's the basis for saying "the aircraft lost GPS-lock and dropped into ATTI-mode"?

@sar104

It did switch to ATTI, twice, but not due to lack of GPS lock. It followed the toilet bowl behavior, so almost certainly due to yaw errors.

 

[DanMan32]

I've once a few months ago had what seemed to be a toilet bowl effect, even though all flight parameters were OK.
In my case I believe it was VPS tracking water waves and currents, disagreeing with GPS/compass. RTH was good.

 

[BrucenYvette]

I see the question, "What's the basis for saying "the aircraft lost GPS-lock and dropped into ATTI-mode"? "

My reply would be my understanding that this is what happens for the aircraft to "drop" into ATTI mode. My understanding is that the loss of GPS-lock causes the drop into ATTI.

I'm a newbie here, so feel free to correct me. Meanwhile, I'm investigating getting the .DAT file from the aircraft. Appreciate y'all who are looking at this!

 

[BudWalker]

I see the question, "What's the basis for saying "the aircraft lost GPS-lock and dropped into ATTI-mode"? "

My reply would be my understanding that this is what happens for the aircraft to "drop" into ATTI mode. My understanding is that the loss of GPS-lock causes the drop into ATTI.

I'm a newbie here, so feel free to correct me. Meanwhile, I'm investigating getting the .DAT file from the aircraft. Appreciate y'all who are looking at this!

Although a loss of GPS sats will cause a switch to ATTI there are other causes. Usually, it has more to do with the Flight Controller not being confident in the location and/or heading that it's computed. That in turn is often caused by a compass error.

 

[BrucenYvette]

Well, guys, looks like I've come to a "dead-end". I'm not able to retrieve the .DAT data file. Not sure why not, but that flight data from December is "wiped". I'm guessing that it's because last week I downgraded my firmware because of DJI's latest "No Fly Zone" changes in their firmware.

I mentioned in the beginning of my post that I've only been flying since June. At the same time that I've been over-the-top happy with the Mavic Pro "bird", my displeasure with DJI Go 4 and their firmware updates has grown exponentially! It seemed like every time I got comfortable with the bird and the App, DJI came along and changed something. Twice caused me not just anguish, but 2 crashes as well.

I finally "quit" DJI Go 4 and started flying Litchi exclusively AND pretty much glitch-free!! Two weeks ago, DJI messed that up when they modified their NFZ settings and I found myself unable to fly one of my favorite places- even with Litchi- because the location was just at the 5-mile edge of a local airport! DJI was "nice-enough" to "accommodate" me by giving me "permission" to fly at my favorite location AS LONG AS I LOGGED ON TO A SPECIAL WEBSITE WHERE THEY WOULD GIVE ME 3 DAYS PERMISSION!! Well, I said to myself, "Self, screw this BS!"

I did a bunch of research and came across NoLimitDronz. Now I can fly Litchi or I can fly an NLD-patched version of DJI Go 4. So, I'm guessing that my firmware downgrade from V01.04.0400 to V01.04.0300 erased my December flight data. Or, perhaps, the fact that I've been flying Litchi 100% since back in October is the issue. Don't know...but currently I'm only showing a flight index of my most recent 5 flights flown by the patched DJI Go app.

So, can you give any theories about what happened on flight you've examined?

 

[BrucenYvette]

My "bird"

 

[Aussie Oldtimer]

In aust, our toilets dont fill like yours do but i understand what you say.

 

[Meta4]

but currently I'm only showing a flight index of my most recent 5 flights flown by the patched DJI Go app

It's unlikely that updates etc would wipe recorded data.
Older flight records normally get overwritten by newer flight records because there's limited space on the internal card.