How to stop a "run away" when Mavic Pro is in your hand?

[Meta4]

So my end conclusion is that I will never know what happened on 23 July "fly away". That the FC has no record of any flight information that day says that some very strange "anomaly" occurred during that 7-8 minute flight.

Just forget about this and get on with your flying, but in future wait for GPS before launching.

 

[tjcooper]

As my point 5) in my last post says, starting in ATTimode would not have changed anything. My system (could be just the NDL app) will take me into GPS mode as soon as enough satellites are found. I have no clue about homeposition location. Some documents say FC sets it to last known HP that was recorded which could be very different from current location. Only way I know of to test HP is to ask for RTH which would be very dangerous if it were miles away. Or it could be first location when enough satellites locked into GPS mode. I just don't have enough cord to put on MP to permit a RTH if one cannot trust the HP.

BTW, I really want to thank both Meta4 and BudWalker for all their comments. I would not have made all the tests I did had I not been "pushed" into giving out more details.

QUESTION: does anyone have a tutorial or app that interprets "log" files? There is both the .txt and the .log type. Would like to see what they say about the 29 June flight.

 

[Kilrah]

Or it could be first location when enough satellites locked

That's what it is, which we already told you and there is no question about. The app says when it records it too...

 

[Meta4]

My system (could be just the NDL app) will take me into GPS mode as soon as enough satellites are found. I have no clue about homeposition location.

GPS and homepoint recording are basic principles which are important to understand to know what your drone is doing and how to fly it safely and easily.
Any DJI drone will automatically be in P-GPS mode as soon as the flight controller is satisfied that it is getting good GPS location data.

Some documents say FC sets it to last known HP that was recorded which could be very different from current location. Or it could be first location when enough satellites locked into GPS mode.

"Some documents" are nonsense.
When you power off, your drone loses the recorded home point and has no home point until it gets good GPS location data again.
At that time it will automatically record a homepoint - wherever the drone is at the time.
So if you launch prematurely before acquiring GPS, your homepoint might be some distance from where you launched.

Only way I know of to test HP is to ask for RTH which would be very dangerous if it were miles away.

All you need to do is look at your screen to see how far the drone is from its home point.
It's easy to do while the drone is starting up.
Before it has a homepoint, the distance indicated shows as NA (not available).
After it has a homepoint, it shows a number (which should be very small while the drone is still on the ground).

If you launch impatiently, you could fly off a hundred yards with the distance showing as NA, then become 0.1, 1, 2, 3 etc after the drone gets a home point to measure distance from.
By understanding how these basics work, you avoid getting into a situation where you are wondering where you are.

I just don't have enough cord to put on MP to permit a RTH if one cannot trust the HP.

DJI's homepoint recording and RTH system are extremely reliable.
Much more reliable than some of the people that fly their drones.
There's no need to attach any cord to your drone.

 

[tjcooper]

@Meta4 why do you make statements without doing the research to be sure you are correct?

The MP user manual does indicate that RTH will go to the last known home point. It indirectly implies that the last recorded homepoint will be used. This is why they do not want you to fly "indoors" because you will not get a set of GPS coordinates to set a new homepoint. This also happens when you are in a very steep walled valley and only 1 or 2 satellites can be found. GPS will not be found. This happened to me when I was flying in the Yuba River gold country in California. If you hit RTH in this situation, strange things will happen.

I knew you would not believe me, so I went to DJI support for MP and asked if the FC uses the last recorded homepoint that can have been recorded many days earlier. His answer after asking his technical support team was "yes, it uses last recorded homepoint". I knew you would not take my word for the technical support from DJI, so I did a screen dump of the last part of the conversation where he confirms for the 2nd time that recorded homepoints will be used if you don't have one for the current flight.

BOTTOM LINE: the FC does have a recorded homepoint if a current one is not found. If you hit the RTH is this situation, strange things can happen. It can either ignore your RTH request entirely and just hover, or it can start to fly in the direction of the last RECORDED homepoint if there is some marginal Lat/Long that the current GPS attempt is trying to formulate. If you get a FULL GPS lock down, then you have a new homepoint and the RTH will be exactly where you are at that moment. I would imagine that "smart RTH" would then take over.

 

[Meta4]

why do you make statements without doing the research to be sure you are correct?

I'm thinking the same thing about you .. but with more justification.

The MP user manual does indicate that RTH will go to the last known home point. It indirectly implies that the last recorded homepoint will be used.

You don't seem to understand and haven't taken in some really basic concepts.
When you power off your drone, it loses the homepoint it recorded and when you power up again it has no homepoint until it gets GPS again, wherupon it will record a new homepoint.

You can verify this easily by from flight data.
The lat and long data columns are blank on startup and stay that way until the drone is getting new position data.
How ridiculous would it be to program the drone to use previously recorded home points?
DJI design engineers aren't that stupid even if you are.

When the manual mentions the last homepoint recorded, that's the last HP recorded during the current flight (becuse it's possible to update and record a new homepoint during a flight).
But it's impossible to go back to a homepoint from a previous flight, because the homepoint is lost when the drone is powered down.

This is why they do not want you to fly "indoors" because you will not get a set of GPS coordinates to set a new homepoint. This also happens when you are in a very steep walled valley and only 1 or 2 satellites can be found. GPS will not be found. This happened to me when I was flying in the Yuba River gold country in California. If you hit RTH in this situation, strange things will happen.

This is nonsense.
If you fly without getting enough sats to have good GPS location data, you have no homepoint.
If you hit RTH without a homepoint and without GPS location data, your drone will just land where it is.

I knew you would not believe me, so I went to DJI support for MP and asked if the FC uses the last recorded homepoint that can have been recorded many days earlier.

You are right ... I don't believe you, because you have no idea what you are talking about.
I don't believe what DJI support told you because it's WRONG.
DJI support people are often a great source of misinformation.
They don't fly drones and just read scripts.
It's not unknown for some of them to say anything just to get you off the phone when you confuse them and they don't have a script to read from.

The flight controller cannot use a homepoint from a past flight because homepoints are lost when the drone powers down.

BOTTOM LINE: the FC does have a recorded homepoint if a current one is not found. If you hit the RTH is this situation, strange things can happen. It can either ignore your RTH request entirely and just hover, or it can start to fly in the direction of the last RECORDED homepoint if there is some marginal Lat/Long that the current GPS attempt is trying to formulate. If you get a FULL GPS lock down, then you have a new homepoint and the RTH will be exactly where you are at that moment. I would imagine that "smart RTH" would then take over.

This is all not true at all.
Bottom line is that you are not playing with a full deck.
Your partial knowledge of drone basics is confusing you and you've wasted far too much of my time with absolute nonsense.

 

[Meta4]

why do you make statements without doing the research to be sure you are correct?

Because you are reluctant to accept my word for anything, and are more confident in your (mis)-interpretation of the manual and what the useless DJI help people might tell you .....
I've found the data from a flight where the drone never had good GPS and never recorded a homepoint.
Here are the start and end of the relevant columns from the data.

The blue columns show the drone's location (zero because of poor GPS)
Pink shows the homepoint stored in memory, at the beginning and right through the flight to the end.
You'll note that there is no homepoint, as the data field is completely blank.
That's because the previous homepoint evaporated when the drone was powered off after the previous point.

Now ... what was that you were telling me?

 

[tjcooper]

@Meta4

i didn't know you had a psychiatric background and made judgements of people like:
"Bottom line is that you are not playing with a full deck."

So I think it is time for you to demonstrate that you are "playing with a full deck". Since I know you don't like to do any research before you make pronouncements, here is a brief list of "qualifications" or "cards" that I would like to know are in your deck

1) educational background: major, school, GPA
2) what industrial experience in what companies that made or deployed drones?
3) have you ever build a drone from scratch components?
4) what specific drones have you flown?
5) do you have part 107 certification?
6) have you ever programmed drones in their native language?
7) what patents do you have in drone technology?
8) how many years of experience with drones and UAV devices?
9) have you ever crashed a drone into the ground?

Add any other "cards" that you think would make people believe that you can make pronouncements without showing the research that should go with it. I really do hope you respond. I think readers would like to know how full is your deck.

 

[Meta4]

@Meta4

i didn't know you had a psychiatric background and made judgements of people like:
"Bottom line is that you are not playing with a full deck."

So I think it is time for you to demonstrate that you are "playing with a full deck". Since I know you don't like to do any research before you make pronouncements, here is a brief list of "qualifications" or "cards" that I would like to know are in your deck

1) educational background: major, school, GPA
2) what industrial experience in what companies that made or deployed drones?
3) have you ever build a drone from scratch components?
4) what specific drones have you flown?
5) do you have part 107 certification?
6) have you ever programmed drones in their native language?
7) what patents do you have in drone technology?
8) how many years of experience with drones and UAV devices?
9) have you ever crashed a drone into the ground?

Add any other "cards" that you think would make people believe that you can make pronouncements without showing the research that should go with it. I really do hope you respond. I think readers would like to know how full is your deck.

No comment on any of the detailed explanation I gave you?
Continuing to assert that I don't know what I'm talking about?
Now you're just being a trolling jerk.

 

[Conservative Nihilist]

Venturing slightly off-topic to make a layman's observation, I must commend all parties for engaging in spirited verbal jousting to express strong differences of opinion, while remaining focused on the topic at hand. With age comes gruffness, bluntness, a thicker skin, and a readiness to debate with gusto. Raising a toast to respondents in this discussion thread, and taking down notes about drones here.

 

[tjcooper]

@Meta4
In regard to your disqualifying my conversation with Tech Support from DJI which I documented above. I am assuming that you immediately called DJI Tech Support and got them to say that upon extensive research that there is no last homepoint saved in the MP? Oh, I forgot, you don't do research with the experts in a field.

By the way, I agree with you that you can get DJI Tech Support to just show you clips from the manuals and say that is the full answer. They tried that with me and I said I needed to get the experts in LA Tech Support to respond to my question. After a 1/2 hour wait on chat they got the answer from top field support in LA that the homepoint is stored. I responded that I needed the Tech Support in Shenzhen to verify the LA answer. That cost another 1.2 hour of wait. Eventually the Product Support manager in Shenzhen concurred that a copy of the last homepoint is recored for the MP.

So I went the "extra mile" to be sure that I was not getting the "fast answer and please go away" from local Tech Support.
Now given this level of investigation, what documentation do you have to disavow what DJI has said?

Oh, your listing of a non-GPS flight means nothing. You did not list where the data comes from. Is it .txt or .dat and is it from RC or the FC? There are many threads in the Forum that show that when you first start a flight inside a building that the startup listing is ZERO Latitude and ZERO Longitude. But that says nothing about whether those Lat/Long are transferred to the FC and ever used. The last hmepoint is still available. It is not clear if and when it can be transferred to the FC under special circumstances.

 

[Meta4]

Now given this level of investigation, what documentation do you have to disavow what DJI has said?

Oh, your listing of a non-GPS flight means nothing. You did not list where the data comes from. Is it .txt or .dat and is it from RC or the FC?

There is no helping you..
Your knowledge of even basic things is faulty and you take no notice when people who know make considerable effort to help you.
And then you repeatedly insult them.
Your lack of basic knowledge about drone functioning is appalling but you seem to think you are an expert.

I have investigated flight incidents ever since DJI made flight data available back in 2015.
I have solved more than a hundred lost drone incidents and found missing drones all over the world.
You can't even find your own flight data or understand what happens when you launch without waiting for GPS, yet you dismiss fact and tell me I don't know what I'm talking about.

 

[dirkclod]

@tjcooper if you choose to disregard what Meta has told you which
is correct and go with what you was told I’m sorry. Maybe you should just talk with them. You are wasting everyone’s time here.
You’ve been told correctly so if you want to argue then do so with
DJI not members that know.
You have a good day and move on.
dc

 

[tjcooper]

I just drop this note for anyone who is looking for the HOMEPOINT from the last flight. On the mobile device I find the directory:

DEVICE:\DJI\dji.pilot.pad\LOG\CACHE\flyPlan
in this directory are many .txt files. They all contain the Latitude and Longitude of the flight.
If you look at the last file and the last entry (assuming you did not rest on the ground long enough for Lat=Long=0 to be set), you will have a homepoint that was set (if indeed it was set). This file appears to just list Lat/Long of sampled points for the whole flight. NOTE: this is ONLY for the NLD application.

If you are using the standard DJI software, look in:
DEVICE:\DJI\dji.go.v4\LOG\CACHE\flyPlan
The same .txt files are present, but they are all encrypted. If someone knows how to decrypt these files, a person probably can get the last homepoint position that was set. I have a communication from DJI that for MP the last homepoint is recorded in an encrypted file but they would not disclose which one. Hope this helps.

I believe the same flyplan type of directory is located on the FC, but I have not searched for this directory. It most likely is encrypted so will be of little use unless you know the decryption algorithm.

 

[Deleted member 103366]

I believe holding both sticks down/inside for 3 seconds (same action as manually starting the motors) would kill the motors, but...that's difficult while holding a tiger by the tail in one hand. But it could have been done as soon as the bird started going sideways.

Under normal circumstances the CSC maneuver will ONLY work if the response to the CSC stick position, set in the App, is set to "Anytime" or its equivalent word.
The default response is "Emergency Only" or equivalent, and leaves the choice of whether or not to stop the motors at the discretion of the drone.
What constitues an emergency??????
In normal circumstances and in "Emergency Only" mode, the drone will not shut down its motors if the drone senses it is in flight i.e. it senses movement. I have tried this with a propless, handheld and wobbled Mavic 2. The motors did not stop.
I have also brought a Mavic Mini, CSC response set to "emergency only" or equivalent, down from 100m with the sticks in the CSC position. The descent was under perfect control the whole way down and the drone even slowed its descent as the ground came within range of the downward looking sensors,. Once the sticks were released the Mavic Mini hovered.

 

[sweetcraver]

found?
I will try to dump the flight logs tonight and see if I have anything on the AC or in the controlller. What is the best way to get a dump?
Ted Cooper

Yesterday morning I was in the process of taking off and felt the remote slip in my hands a little just as I was nudging the stick to lift off.
My mavic pro 2 shot off at high speed about a foot off the ground while I frantically struggled for control. No response whatever
To my attempts to stop it.
It crashed into a bike rack with a loud clang. That was a terrible, terrible sound but it was better than hearing a scream.
And bike racks don’t have lawyers.
I had no idea what Ii would find at the end of my 70 foot walk to recover whatever remains were waiting for me.
The drone was not in pieces. It appeared intact. The lights were blinking. On all four arms. A quick inspection of the props turned up no sign of damage.
I brought the drone back to the landing pad and waited for my heartbeat to settle down a bit before preparing to launch again. I did not expect much, considering the force of that impact.
I took off to a low hover without incident. It seemed to be operating normally and the camera was performing as if nothing had happened. I went ahead with my original flying plan and brought it back when the battery had dropped to about twenty percent.
As I was changing batteries i happened to notice something I had missed in my quick inspection. A small hunk was missing from one of the blades. I looked closer and found a hairline crack a little under 1/4” long in the trailing edge of another prop. Then a missing tip on still another plus another small hairline crack.
My drone was flying normally with props that could have shredded themselves any time.
Needless to say I was shaken by this experience but felt very lucky at the same time.
I have no idea what I could have done to trigger a low level flyaway.
It goes without saying I was in awe of the ruggedness of my little machine and my hat is off to the DJI folks for putting together such a fine product. Well, with the hell of the Chinese team under their direction.
I didn’t mean for this to be so long.

 

[slup]

...I have no idea what I could have done to trigger a low level flyaway.

The absolutely best way to find out the reasons for thing's that appear odd ... is to look into the flight log.

Go here & upload the log & check out exactly what happened & how you commanded the craft ---> DJI Flight Log Viewer | Phantom Help (they explain there where to find the log in your mobile device). If you later need assistance to interpret the information just share the link they provide when you have uploaded the log.

 

[Meta4]

I have no idea what I could have done to trigger a low level flyaway.

As above ... post your flight data.
And a description of the powerup/launch site might be helpful.

And since this thread is such a mess, it would be a good idea to start a new thread for your incident rather than adding to this one.

 

[sweetcraver]

I will attempt to put a new post together with your suggestions.

 

[MAvic_South_Oz]

I will attempt to put a new post together with your suggestions.

Be sure to post it in the Mavic Crash / Flyaway section . . . much more attention than here or other aircraft sections.

Mavic Crash & Flyaway Assistance

Click New Post and put something suitable in the title, post up any thing relative, and attach the flight log (txt) or the link to the PhantomHelp or Airdata reports.

Click Post Thread, done