Mavic Air 2 fell out of the sky

[Meta4]

Thanks for the response and I would have to agree, better safe than sorry and the process is very simple. It can only improve the stability of your UAV and should be viewed like any other maintenance.

If your drone is flying normally, recalibrating the IMU or compass can't improve anything.
If either needs recalibrating, you would know it.

The common better-safe-than-sorry comment isn't valid.
It's better to understand how your drone works and what recalibrating can and cannot do.

 

[March411]

If your drone is flying normally, recalibrating the IMU or compass can't improve anything.
If either needs recalibrating, you would know it.

The common better-safe-than-sorry comment isn't valid.
It's better to understand how your drone works and what recalibrating can and cannot do.

Meta, not trying to be smuge, simply trying to understand the logic. So by your statement are you stating that by doing it unless directed it will somehow make the UAV less stable because it wasn't prompted?

I rotate the tires on my car regularly even if the car is driving fine and isn't pulling. Preventive maintenance, why wait until it states to be done, it could fail in the air?

Preforming preventative maintenance could/would ensure stability. DJI gives you that ability for a reason.

 

[Meta4]

Meta, not trying to be smuge, simply trying to understand the logic. So by your statement are you stating that by doing it unless directed it will somehow make the UAV less stable because it wasn't prompted?

I didn't say anything like that.
I said that it's completely unnescssary

Preventive maintenance, why wait until it states to be done, it could fail in the air?
Preforming preventative maintenance could/would ensure stability. DJI gives you that ability for a reason.

You think that because you don't understand what compass calibration does and imagine it might be used as "preventative maintenance".
Well it isn't and understanding what it actually does and when it's needed (almost never) woul;d make you a safer flyer than imagining how things work.

 

[March411]

I didn't say anything like that.
I said that it's completely unnecessary

You think that because you don't understand what compass calibration does and imagine it might be used as "preventative maintenance".
Well it isn't and understanding what it actually does and when it's needed (almost never) woul;d make you a safer flyer than imagining how things work.

"You think that because you don't understand what compass calibration does and imagine it might be used as "preventative maintenance".

Calibration aligns the drones' flight system with the Earth's magnetic north, not its true north. The internal magnetometer that can be affected by things like metal, reinforced concrete, buildings, and antennas/towers. A poorly calibrated system could lead to a crash.

The IMU detects any inconsistencies in attitude and movement on the horizon to help the UAV fly straight and prevent drift. It uses internal sensors, the gyroscopes and accelerometers to deliver acceleration and orientation information that can be used to calculate position and velocity.

DJI recommends that we calibrate on 30 day intervals, if we move greater than 30 miles to fly @ a new location or crash.

So I understand both but I am still unclear how completing these pieces of preventative maintenance would be unnecessary and if completed with some degree of consistency may prevent crashes or fly-aways. They are both so simple and keep the aircraft in check.

And Meta, for the record I have a ton of respect for you and what you do for the site and the membership. I read the majority of you posts to learn from you vast knowledge. Just attempting to understand the logic.

 

[Zbip57]

Calibration aligns the drones' flight system with the Earth's magnetic north, not its true north. The internal magnetometer that can be affected by things like metal, reinforced concrete, buildings, and antennas/towers. A poorly calibrated system could lead to a crash.
[...]
Just attempting to understand the logic.

For a really excellent explanation on how the compass works and what calibration actually does, read this post by @sar104 :
mavicpilots.com/threads/a-short-explanation-of-compass-function-calibration-and-errors.90792/

One of the most common causes of a flyaway is a mis-calibrated compass, when it didn't actually need recalibration. For example, when attempting to launch from a spot where there is significant magnetic interference, such as from on top of metal manhole cover, the roof of your car, or concrete with metal re-bar in it, you might get a message warning of magnetic interference and recommending a compass calibration.

But doing a calibration while in that area of interference only makes things worse. It is in effect realigning the compass to compensate for that magnetic interference. When you then take off and leave the area of interference, the misaligned compass causes a conflict with the IMU resulting in loss of control.

What Meta4 is saying, a re-calibration wasn't necessary in the first place. There was nothing wrong with the compass calibration to begin with. The proper thing to do is to leave the calibration alone and simply move away from the area of magnetic interference before trying to take off.

 

[MS Coast]

For example, when attempting to launch from a spot where there is significant magnetic interference, such as from on top of metal manhole cover, the roof of your car, or concrete with metal re-bar in it, you might get a message warning of magnetic interference and recommending a compass calibration.

And you may not get a message, so you're blissfully unaware that the compass is significantly biased and the drone may not operate properly.

It's good practice to glance at the map to verify the compass operation immediately after takeoff. Is the drone really pointing in the direction indicated?

 

[March411]

Gentlemen, I appreciate both of your responses and understand what Yaros was stating as "it may be controversial".

I guess I will give up because my attempt was to determine the logic for preventative maintenance as described by DJI to be unnecessary. When calibrating the compass the software warns you to complete the task away from metal objects and electrical equipment, I would hope that pilots would heed the warning and complete the calibration correctly.

That being said I will bail on the conversation as I already took the OP off topic and it appears it could become a circular conversation.

Everyone's responses are appreciated!

 

[Meta4]

So I understand both but I am still unclear how completing these pieces of preventative maintenance would be unnecessary and if completed with some degree of consistency may prevent crashes or fly-aways. They are both so simple and keep the aircraft in check.

Your understanding of what compass calibration actually does is quite wrong.
To find out the facts read the first post in this thread:

A short explanation of compass function, calibration and errors.

BACKGROUND The aircraft compass is often misunderstood, both in terms of function and purpose, but it is important to understand what the compass measures, why, and what happens to that information. At the most basic level the purpose of the compass is to measure the earth’s magnetic field in...

mavicpilots.com

Neither the compass or IMU lose their calibration over time and the "preventative maintenance" you imagine is not necessary.

 

[MS Coast]

I guess I will give up because my attempt was to determine the logic for preventative maintenance as described by DJI to be unnecessary.

Where does DJI prescribe preventive maintenance? For the Air 2S, here are the only mentions in the user manual of the IMU and calibrating the compass. There's no mention of IMU calibration.

 

[March411]

From their website:

DJI recommends to calibrate the compass of your DJI Mini 2 in the following situations when flying outdoor:
1. Flying at a location further than 31 miles ( 50 km ) away from the location the aircraft was last flown.
2. The aircraft has not been flown for more than 30 days.
3. A compass interference warning appears in DJ Fly and/or the aircraft status indicator blinks red and yellow alternately.
Thank you and fly safe always.

 

[MS Coast]

From their website:

DJI recommends to calibrate the compass of your DJI Mini 2 in the following situations when flying outdoor:
1. Flying at a location further than 31 miles ( 50 km ) away from the location the aircraft was last flown.
2. The aircraft has not been flown for more than 30 days.
3. A compass interference warning appears in DJ Fly and/or the aircraft status indicator blinks red and yellow alternately.
Thank you and fly safe always.

It's odd that that text appears in the Mini and Mini 2 manuals, but isn't included in the Air 2S or Mini 3 manuals. In any case, it's not a recommendation for routine maintenance, just for those special circumstances. And there's no mention of calibrating the IMU.

I'm not hopping on one or the other side of an argument, and it's unlikely that calibrating the compass or IMU unnecessarily will do any harm. But, outside those three situations, it's probably unlikely that bad IMU or compass calibration is the cause of a problem and it's a bad idea to assume that calibrating will solve the particular problem without investigating the real cause. I think the same applies to firmware updates - often blamed, seldom the cause. Assuming the wrong answer is a great way to avoid finding the right one.

Yes, you can tell it's been raining all day here and I'm having to satisfy scratch my itch to fly by loitering on this forum.

 

[Meta4]

From their website:

DJI recommends to calibrate the compass of your DJI Mini 2 in the following situations when flying outdoor:
1. Flying at a location further than 31 miles ( 50 km ) away from the location the aircraft was last flown.
2. The aircraft has not been flown for more than 30 days.
3. A compass interference warning appears in DJ Fly and/or the aircraft status indicator blinks red and yellow alternately.
Thank you and fly safe always.

DJI has been spreading compass misinformation and confusing flyers for years.
Read the link I provided to get actual facts about what compass calibration does and when it is actually needed.

 

[March411]

DJI has been spreading compass misinformation and confusing flyers for years.
Read the link I provided to get actual facts about what compass calibration does and when it is actually needed.

Appreciated!

I read most (a lot, they have over 25K combined) of sar104 and Meta4's posts, I currently follow Meta because of the wealth of information.

 

[GekkoState]

Just a quick update for anyone who was curious about why the aircraft wouldn’t link up, but I still wonder what caused the crash in the first place and how it would malfunction after only an 8 foot drop into the grass

 

[Paul2660]

Since the MP2 will give you the error message "compass needs calibration" if you:
1. have not flown the drone in over 30 days,
2. Have moved more than 31 miles since last flight

Is the recommendation not to proceed with a compass calibration? It only takes about 15 seconds and if you don't proceed with the calibration, you will continue to see the error message on the controller screen.

This is true with M2P, with either stock controller or smart controller (version for M2 Pro).

For me it's just simpler to process the calibration and remove the message.

Paul

 

[sar104]

Since the MP2 will give you the error message "compass needs calibration" if you:
1. have not flown the drone in over 30 days,
2. Have moved more than 31 miles since last flight

Is the recommendation not to proceed with a compass calibration? It only takes about 15 seconds and if you don't proceed with the calibration, you will continue to see the error message on the controller screen.

This is true with M2P, with either stock controller or smart controller (version for M2 Pro).

For me it's just simpler to process the calibration and remove the message.

Paul

With the M2P I generally ignore the request provided that the compass is reading accurately and the aircraft is not crabbing in forward flight, which is usually a sign of a slightly out-of-calibration compass. If either of those two indications arise I recalibrate.