There’s no fool like an old fool...Mavic Mini lost!!

[OldGuy]

i fly all over the place mostly in Wales and have gone well over 100 miles from home on several occasions to fly ,i have not taken the MM any further than 50 miles from home yet and have not been asked to CC i use my hand held compass method on both my drones to establish magnetic north ,and to check if there is anything in the ground that could affect the compass in the drone
to do that i hold the compass at chest height find north and then lower it slowly to the ground if the needle stays pointing to the north point on the ground ,then i know that there is nothing affecting it, but on several occasions the needle has moved quite a way off north due to something in the ground affecting it , then i move to another point and try again

The area where I live in the south of Spain is an old volcanic region so perhaps this has something to do with it. I am really intrigued now as I thought everyone was like me carrying out regular CC.
The next time I fly I will try out your compass idea and see if I can get to the bottom of this.

 

[OldGuy]

It's a matter of much misunderstanding and DJI's poor communications on the topic have spawned a lot of superstition about compass calibration.
The people that recommend frequent compass calibration don't understand what compass calibration actually does or when it's really necessary.
The only thing that compass calibration does is to identify and measure the magnetic fields that are part of the drone itself.
That is so they can be ignored, allowing the compass data to show actual magnetic fields in the flying environment rather than being influenced by the electromagnetic fields within the drone.

It has nothing to do with distance from anywhere and doesn't really need to be done at time intervals or after travelling.


Compass calibration played no part in your flight incident and it's quite likely that your other ideas about your "mistakes" are also incorrect.
If you post your recorded flight data, we should be able to eliminate some or all of your other suggested causes and possibly find out what really happened.

One of the main reasons that I am used to CC is because I started my drone life with a Hubsan H501S. This drone required a CC every time you changed the battery. You could not fly unless you did this. So when I moved onto DJI drones I accepted that CC was part of their strategy as well and never questioned it. Now you have me thinking otherwise although when prompted by either of my Mavics to do a CC it is mandatory and not a request!? This from the Mavic 2 manual:
Calibrating the Compass:
It is recommended that the compass is calibrated in any of the following situations when flying outdoors
1. Flying at a location 31 miles (60 km) away from the location the drone was last flown.
2. The aircraft has not been flown for more than 30 days.
3. A compass interference warning appears in DJI Go 4 etc etc.

I will look into digging out the flight log and let you know what I find. Thank you for your kind attention and help with this issue.

 

[sirbadger]

I will look into digging out the flight log and let you know what I find. Thank you for your kind attention and help with this issue.

Mavic Flight Log Retrieval and Analysis Guide

With the introduction of the Mavic Mini there has been a noticeable uptick in the number of posts requesting help with lost or crashed aircraft. While there is plenty of help and advice available on this forum, and detailed guidance and options on several other websites, I thought that perhaps a...

mavicpilots.com

 

[Meta4]

This from the Mavic 2 manual:
Calibrating the Compass:
It is recommended that the compass is calibrated in any of the following situations when flying outdoors
1. Flying at a location 31 miles (60 km) away from the location the drone was last flown.
2. The aircraft has not been flown for more than 30 days.
3. A compass interference warning appears in DJI Go 4 etc etc.

Just to confuse everyone DJi in earlier models used to recommend compass calibration related to some distance.
It wasn't needed at all but they put it in the manual and started confusing everyone.
Eventually the got it right with the manual for the Phantom 4 pro which said:

But with the Mavic 2, they came up with a new way to confuse people again by printing what you put above and programming some M2s so that they would force the user to needlessly recalibrate each 30 days or 60 kilometres, despite there being no physical reason for it.

 

[Fearless Flight]

I’ve been flying drones for at least 6 years and only do a CC if prompted and have never had a single issue. With my MP I did an initial CC and never did another one the entire time I owned it.
My M2P definitely will ask every 30 days and seems to be much more demanding of a CC in general and I do it every time I’m prompted which is probably every 3rd flight. Kind of a pain actually.

To the OP you said you should have waited for RTH but that sounds like you were going to let the battery run down enough to automatically do a RTH. If you shut of the controller it should initiate a RTH without burning through so much battery in case you need the distance.

 

[Dan C]

Eventually the got it right with the manual for the Phantom 4 pro which said:

Don’t calibrate around your cell phone, eh?

That would be a neat trick since my cell is the device running the software telling me to calibrate.

But to the issue of calibration, I’ve flown in three different countries, locations thousands of kilometer apart.

As best I can remember, I’ve had to recalibrate on the first flight after traveling a long way. Magnetic north would be different over such distances, though I don’t know if that’s relevant.

I’ve also flown several days from the same park near my home, then out of the blue one of those days it’s wants to be calibrated.

My experience has been that there is little rhyme or reason some of the time that I’m aware of, but that doesn’t mean there isn’t a reason.

Bottom line: I don’t lose any sleep over it. If it asks, I calibrate.

As to the OP, I appreciate the honesty, but the story is a bit confusing to me. However, what jumped out to me was the possible lack of Home Point.

I spend most of my time these days in central China. A very noisy environment. I generally set my RTH altitude to 120 meters, and never launch without sufficient GPS signals. I’m quite paranoid about loss of signal.

The OP by suggests he didn’t have a Home Point set, which suggests inadequate GPS signals. Which makes me scratch my head about the mention of RTH. How could that be possible when it doesn’t know where Home is? Would it set it later when it finally got enough signals, possibly far far away from the launch point?

Or did it actually never enter RTH?

 

[Bigbird48]

I agree about only doing CC when asked. I have flown 3000 miles across country and flew in several different locations there and never was asked to do a CC. Then I fly home fly in my back yard every day from the same take off platform and suddenly get asked to do CC go figure.

 

[EricJT]

i am glad i am not the only one, though i do get some funny looks if there are people walking by as i am doing it, you can see them thinking i wonder what's he up to and sometimes they will stand and watch

Add me to this list....I orient the AC to north prior to takeoff. I was told it is not necessary, but old habits die hard.

 

[EricJT]

Don’t calibrate around your cell phone, eh?

That would be a neat trick since my cell is the device running the software telling me to calibrate.

But to the issue of calibration, I’ve flown in three different countries, locations thousands of kilometer apart.

As best I can remember, I’ve had to recalibrate on the first flight after traveling a long way. Magnetic north would be different over such distances, though I don’t know if that’s relevant.

I’ve also flown several days from the same park near my home, then out of the blue one of those days it’s wants to be calibrated.

My experience has been that there is little rhyme or reason some of the time that I’m aware of, but that doesn’t mean there isn’t a reason.

Bottom line: I don’t lose any sleep over it. If it asks, I calibrate.

As to the OP, I appreciate the honesty, but the story is a bit confusing to me. However, what jumped out to me was the possible lack of Home Point.

I spend most of my time these days in central China. A very noisy environment. I generally set my RTH altitude to 120 meters, and never launch without sufficient GPS signals. I’m quite paranoid about loss of signal.

The OP by suggests he didn’t have a Home Point set, which suggests inadequate GPS signals. Which makes me scratch my head about the mention of RTH. How could that be possible when it doesn’t know where Home is? Would it set it later when it finally got enough signals, possibly far far away from the launch point?

Or did it actually never enter RTH?

Or did it still have the previous flight's RTH point?

 

[RickinWaST]

Thanks for sharing what you believe was the cause or causes of losing your drone. It generates insightful discussion.

The statement below was made in the discussion and as a new drone (M2P) owner of a few months I‘d like to get a clarification...

“If you shut of the controller it should initiate a RTH without burning through so much battery in case you need the distance.”

 

[OldGuy]

Thanks everyone for your input and comments. I don’t know if the home point was recorded or not. I came back from a hill 10 km away and took off from my garden. It was getting late so I was in a hurry…..another mistake. When my tablet went dark and the remote lights started flashing I realised later that I should have switched the remote off. However I wasn’t sure that the home point had been recorded. I hesitated then panicked and lost my day old Mavic Mini!! I have a new one but still haven’t got over losing that one.
As for the compass calibration I follow instructions but I seem to do quite a lot in comparison to the rest of you guys. I can only think that it is something to do with the area I live in!?

 

[Meta4]

The area where I live in the south of Spain is an old volcanic region so perhaps this has something to do with it.

I don’t know if the home point was recorded or not.
However I wasn’t sure that the home point had been recorded. I hesitated then panicked and lost my day old Mavic Mini!! I have a new one but still haven’t got over losing that one.

Magnetic north would be different over such distances, though I don’t know if that’s relevant.

As I pointed out in post #19, it has nothing to do with your specific location, nothing to do with distance from anywhere and it has nothing to do with the difference between map north and magnetic north etc.
It is only about your drone's magnetic fields and they don't change unless you modify the drone.

 

[Fearless Flight]

Thanks for sharing what you believe was the cause or causes of losing your drone. It generates insightful discussion.

The statement below was made in the discussion and as a new drone (M2P) owner of a few months I‘d like to get a clarification...

“If you shut of the controller it should initiate a RTH without burning through so much battery in case you need the distance.”

That statement was in reference to the OP saying he should have waited and let the MM go into RTH. My thinking was that the OP was going to let the battery run down which will automatically trigger the MM to go into RTH. I mentioned that because I wouldn't let the battery run down to trigger the RTH when you can turn off the remote to trigger the RTH without burning the battery down just in case you need the extra flight time.

This is all for naught if a home point was never set though. If you don't hear the home point set do not continue, wait until you hear it or all the other safety features built in will not help.

 

[Meta4]

I don’t know if the home point was recorded or not.

However, what jumped out to me was the possible lack of Home Point.
The OP by suggests he didn’t have a Home Point set, which suggests inadequate GPS signals. Which makes me scratch my head about the mention of RTH. How could that be possible when it doesn’t know where Home is? Would it set it later when it finally got enough signals, possibly far far away from the launch point?

Or did it actually never enter RTH?

This is all for naught if a home point was never set though. If you don't hear the home point set do not continue, wait until you hear it or all the other safety features built in will not help.

If the OP had GPS his drone will have recorded a home point.
Even if he was impatient and launched early, the drone would have recorded a home point as soon as it got a good GPS position and that won't make much difference as it wouldn't be far from where he launched.
And it's common to have recorded a home point without hearing the message ... but it's very easy to confirm that the drone has a home point.
If the distance is showing on the bottom left of the screen, that's the distance from ... the Home Point.

Or did it still have the previous flight's RTH point?

That's not possible.
Every time you power the drone off, it loses its recorded home point.
When you power on again, it has a blank home point until it gets good location data again.

But all of this guessing is pointless and just wasting time.
If the OP wants to find out what really happened and maybe learn something from the experience, he has to post the recorded flight data.
The data will show what actually happened.
The facts are always going to be a lot more useful than guessing (particularly when people are making guesses without understanding the basics of how the drone works).

 

[Meta4]

Thanks for sharing what you believe was the cause or causes of losing your drone. It generates insightful discussion.

It doesn't matter what people believe if they haven't looked at what actually happened.
A lot of this thread is just confusing people unnecessarily.

The statement below was made in the discussion and as a new drone (M2P) owner of a few months I‘d like to get a clarification...

“If you shut of the controller it should initiate a RTH without burning through so much battery in case you need the distance.”

If you shut off the controller it will initiate RTH.
It won't come home any faster or slower than pushing the RTH button will.
It will come home at a slow cruise speed that is slower than you can fly when you are in control (and not the best speed for max distance).
In headwind situations or if the battery is running low, that might not be a good thing.

 

[Dyn Jarron]

I hate to be added to the list of lost Mavic Minis but here I am. However I must say that it was my fault not DJI as I panicked! I’ve been flying R/C for over 40 years and now have a few years on drones so there is no excuse. This was my second MM having returned the first one due to a disappointing CE range. So here I am on my favourite hill 18th December with nothing around for miles. I fly the FCC version of the MM out almost 2 km and I am very happy due to the excellent range that it has. Unfortunately a cold wind started to blow so I packed up and set off home. Once home as I had proven the FCC MM I decided on one more flight from my garden before calling it a day. Now here is my first mistake I didn’t do a compass calibration which is most unusual for me as I am a big believer in CC. The next mistake was not hearing “The Home Point has been updated please check it on the map” message. I took off full of confidence and flew out across the valley (my place is 350 m above sea level on the side of a mountain). Next mistake was my premature over confidence. Instead of flying VLOS (I know you guys are going to jump on me because of this) I flew out around 600 m saying to myself “I've got a FCC MM so no problem”!! Suddenly everything went dead. I lost the tablet screen, all 4 lights on the remote stared flashing. Now here is the final mistake. I didn’t wait for the RTH to kick in. I reasoned that if I pulled back on the remote stick I would fly backwards along the outgoing flight path. However I should have put the remote down and waited for the RTH.
A futile search of the are revealed nothing. Find My Drone showed the aircraft heading to the coast and out to sea. The Flight Data Centre showed the outgoing flight path and the beginning of a RTH which was interrupted (by me fiddling with the sticks I suppose) which then resulted in the aircraft flying into the side of the mountain.
I returned to my office and immediately ordered another MM CE version which on a good note arrived on Christmas Eve. Since then I have flown this one several times and by switching to manual in Channel Mode have managed to get out around 2 km on 2.4 GHz. I didn’t try this with my first MM unfortunately.
I still look out over the valley and wonder what happened to my poor ill fated Mavic Mini.
I now am the proud owner of a Mavic Mini FCC remote but no drone! By the way I can confirm that it won’t pair with my CE drone!!
Final note: I forgot to put my phone number on the aircraft….all my other drones have it!!

OldGuy/Old Fool!!

Thanks for your honest story! Sorry for the loss wish everyone was as honest.... Better luck next time...

 

[Paulf10]

,i have a routine where i use a small hand held compass to find magnetic north and set my take off mat to north before i fly and i swear by it and won't fly until i have done it that way i know that my Mavic is facing north because i can visually see it on the screen

Thanks OMM! Ive never heard of that and I’ve never done that but I’m going to from now on!????

 

[EricJT]

That's not possible.
Every time you power the drone off, it loses its recorded home point.
When you power on again, it has a blank home point until it gets good location data again.

Meta4, thank you for clarifying this point....I was operating under a misconception from my P2V days that the last recorded home point was stored in memory and only overwritten when a new home point was set.

 

[Dan C]

So, what do say, @OldGuy

Are you willing to post your logs of the flight? I know I for one am curious.

 

[Peio64270]

The reason I should have done a compass calibration is because I had done one on the hill some 10 km away from home. I had never flown the new MM from my place so should have done a CC for the first flight in a new location even though I was not prompted by the Fly app. This is one of the basic rules of drone flying which I ignored/forgot.

Compass calibration has nothing to do with magnetic anomalies external to the drone. It just manage with internal interferences which are usually a constant till you change something in the hardware or in the payload. Imagine a jet or a high sea vessel calibrating its compasse(s) every 20 milles it travels