Lost Mavic after loss of connection

[Meta4]

Why would you assume that I don't understand what calibrating the compass actually does?

Probably because you are advocating frequent unnecessary calibration of the compass.

Do the research - you'll find more than one experienced UAV pilot who agrees with my suggestion.

That you can find more than one person agreeing with something that's incorrect doesn't surprise me at all.
The compass is the most misunderstood aspect of flying.
It's the subject of more myth, misinformation and superstition than probably anything else drone-related.

Even DJi who started the misinformation have finally corrected it in the Phantom 4 pro manual, but stupidly continue to spread misinformaton in the Mavic manuals.

 

[Meta4]

Compass might be calibrated against an undetected magnetic / metallic interference, thus throwing the compass off without knowing it.

It's probably impossible to give a bad compass calibration.
It will either calibrate or reject.
Calibrating just measures the magnetic fields that rotate while you turn the drone.
Anything else can then be assumed to be outside the drone.

 

[RayOZ]

Thank you. DJI have a lot to answer for and it sounds like a possible warranty case!

Well, unless the you didn't install the battery correctly and it popped out during flight. Hope you find it. If you do, the internal flight log/dat file might be able to shed some light.

 

[deleted member 877]

Probably because you are advocating frequent unnecessary calibration of the compass.

That you can find more than one person agreeing with something that's incorrect doesn't surprise me at all.
The compass is the most misunderstood aspect of flying.
It's the subject of more myth, misinformation and superstition than probably anything else drone-related.

Even DJi who started the misinformation have finally corrected it in the Phantom 4 pro manual, but stupidly continue to spread misinformaton in the Mavic manuals.

How can you really be sure about this? Are you a subject matter expert or simply wanting to make us think that you are. From the start, I said that it WOULD NOT HURT to regularly calibrate the compass - that's not the same as "advocating frequent unnecessary calibration of the compass". Please get over yourself if you can possibly do that.

 

[Meta4]

How can you really be sure about this? Are you a subject matter expert or simply wanting to make us think that you are.

You decide
Meta4

 

[DanMan32]

Many have found the M2 to ask for calibration every 30 days or over a certain number of miles from last flight. I can't remember if that was 30 or 300 miles.
I've not seen this myself. I have flown it 40 miles (at work indoors, sometimes getting GPS lock) and just over 30 days before damaging it and needing repair.

 

[Meta4]

Many have found the M2 to ask for calibration every 30 days or over a certain number of miles from last flight. I can't remember if that was 30 or 300 miles.
I've not seen this myself. I have flown it 40 miles (at work indoors, sometimes getting GPS lock) and just over 30 days before damaging it and needing repair.

It would seem that DJI have programmed it to ask after 30 days.
No-one has come up with a good reason for them to do this.
Distance from anywhere is irrelevant to compass calibration and time since recalibration should also be.
My P4 pro has never had anything calibrated and has had almost two years of hard professional work over large distances.
It still flies as well as the day it came out of the box.

 

[deleted member 877]

It would seem that DJI have programmed it to ask after 30 days.
No-one has come up with a good reason for them to do this.

Maybe, just maybe DJi agrees with what I and others have been suggesting. But then DJi may not have expert knowledge of their own products like you do - LOL

 

[DanMan32]

Or the other way around.

But let's say Meta is right, that is how the Mavics are designed to use the compass.

Some have found that demagnetising the compass has improved reliably. It could be they build up magnetism rather easily but gradually over time where regular calibration compensates for it up to a point.
That wouldn't explain the calibration over distance though, only the 30 day aspect.

 

[Simmo]

Maybe, just maybe DJi agrees with what I and others have been suggesting. But then DJi may not have expert knowledge of their own products like you do - LOL

From the DJI site:
Tip To Help Avoid compass interference and crash.


1/ Never calibrate Compass unless prompted to.

2/ start AC leave until you receive enough gps lock ,

3/ if you get Compass interference turn off AC and move to another location,
without interference.

4/ In bottom left hand corner on your map you will see small red triangle, check to make sure that this triangle is pointing in the same direction (heading) as your AC, this will show good compass on the ground.

Raise AC to height of 8ft
Hover for 20 seconds
Fly forward 2ft
Backward 2ft
Left 2ft
Right 2ft
Up 2ft
Down 2ft
Yaw left
Yaw right
Each time returning to hover position
If you have a good horizontal each time, you will then know you have good GPS good IMU and good Compass, and your ready to fly.

 

[Meta4]

Maybe, just maybe DJi agrees with what I and others have been suggesting. But then DJi may not have expert knowledge of their own products like you do - LOL

Maybe ... I don't think so.
DJI have always been terrible at communications.
There are plenty of examples of important things left out, incorrect things put in and inconsistencies.
They almost got the compass information right for the P4 pro manual but there are other things they have wrong.
If you understood what compass calibration does, you'd understand what I've said.
Calibrating the compass has nothing to do with distance from anywhere or time since recalibrating.

 

[Oli34]

Well, the reason I posted was advice on possible malfunction and therefore warranty. Flight data shows that signal was excellent until a mili second before loss. Craft was hovering when it vanished.
As a responsible pilot I had checked everything, I’m looking forward to DJI response.

 

[choo choo]

How about this for all you compass boffins.
During WW2 the Germans invented a magnetic torpedo which homes in on the magnetic properties of ships built with steel by allies which when they are forged in the Northern Hemisphere have the magnetic field of the steel set to a certain polarity of the surface of the earth where it is forged.
This meant that the torpedoes wouldn’t ‘home in’ on German or Axis shipping as the polarity of the steel was opposite to the allies (following me so far).
When the allies discovered this, they laid very powerful cables under the river Thames (London) and other places, and passed shipping over it.
The cables were powerful magnets and changed the polarity of the steel of the ships hull. This resulted in the torpedoes not being able to home in on many targets.
I just wonder if the MP being made in China and flown in, say the USA, it initially needs the compass calibrating for the earths magnetic field which is different in different countries before flying for first time. Just a thought.

 

[deleted member 877]

Maybe ... I don't think so.
DJI have always been terrible at communications.
There are plenty of examples of important things left out, incorrect things put in and inconsistencies.
They almost got the compass information right for the P4 pro manual but there are other things they have wrong.
If you understood what compass calibration does, you'd understand what I've said.
Calibrating the compass has nothing to do with distance from anywhere or time since recalibrating.

One thing I do understand is that there is absolutely no reason to believe that you actually know what you're talking about. I'll follow advice coming from more credible sources.

 

[Meta4]

I just wonder if the MP being made in China and flown in, say the USA, it initially needs the compass calibrating for the earths magnetic field which is different in different countries before flying for first time. Just a thought.

No ... it won't make any difference.
Because calibrating the compass is completely unrelated to where you are, how far the drone has been moved etc, etc and only measures the magnetic fields that are part of the drone so they can be ignored.
If it was important or made any difference, DJI would advise you to calibrate before using ... and they don't.

 

[Oli34]

Possibly. But without the aircraft they may not be able to determine cause definitively. It will be interesting to see how they respond.

Dear Customer,


Thanks for your patience.

This is Lydia from data analysis team, and I will be assisting you on this case from now on for related inquiries about data analysis.

For your case CAS-2381915-Q9L1Q1, we have finished the analysis, and the result is as follows:
1. The aircraft worked in GPS mode during the flight;
2. T=12 s, the flight log showed " battery state absent";
3. T=168 s, h=84.8 m, D=211 m, the flight log showed "battery state absent" again, then the data ended.

According to the analysis, the incident was not caused by a product malfunction. Please pay attention to the battery installation before launching the aircraft.

If you could not recover the product and consider to purchase another one, we can offer you a 15% off discount for Mavic 2 Pro without the charger and remote controller. Please kindly send us the following information if you would like to accept the Following offer. 15% off an aircraft only.

Can the battery just pop out after it’s clicked in? Surely that’s not my fault as it flew until this disaster.

What do you think?

 

[deleted member 877]

Can the battery just pop out after it’s clicked in? Surely that’s not my fault as it flew until this disaster.

What do you think?

I would think that if the battery was not properly inserted the drone would not power up. My guess is that the battery was faulty.

 

[Oli34]

Can a battery be half in? I always check for a click? I’m thinking that DJI are pulling a fast one here...

 

[sar104]

Dear Customer,


Thanks for your patience.

This is Lydia from data analysis team, and I will be assisting you on this case from now on for related inquiries about data analysis.

For your case CAS-2381915-Q9L1Q1, we have finished the analysis, and the result is as follows:
1. The aircraft worked in GPS mode during the flight;
2. T=12 s, the flight log showed " battery state absent";
3. T=168 s, h=84.8 m, D=211 m, the flight log showed "battery state absent" again, then the data ended.

According to the analysis, the incident was not caused by a product malfunction. Please pay attention to the battery installation before launching the aircraft.

If you could not recover the product and consider to purchase another one, we can offer you a 15% off discount for Mavic 2 Pro without the charger and remote controller. Please kindly send us the following information if you would like to accept the Following offer. 15% off an aircraft only.

Can the battery just pop out after it’s clicked in? Surely that’s not my fault as it flew until this disaster.

What do you think?

Yes - it has been demonstrated that the battery can be inserted without properly latching, and still power up, but I'm not sure how they were able to determine that definitively without the aircraft DAT file.

 

[BudWalker]

......

For your case CAS-2381915-Q9L1Q1, we have finished the analysis, and the result is as follows:
1. The aircraft worked in GPS mode during the flight;
2. T=12 s, the flight log showed " battery state absent";
3. T=168 s, h=84.8 m, D=211 m, the flight log showed "battery state absent" again, then the data ended.
.......

There is something not right about this. The .txt log you submitted only has 141.8 secs of data. Their analysis shows data at 168 secs. Did you submit the tablet .DAT to DJI?