How many of you do compass calibration before take off?

[Joely-Bird]

But you guys have convinced me, unless prompted by my app, I'll not do it \o/

Even when prompted by the app, just have a quick 'sense check' first... I recently got prompted to calibrate while sitting on a concrete jetty and almost did until I realized that there was a bunch of steel girders under the concrete, that would be driving the compass nuts. In this situation, the compass will be fine once you get a few meters up in the air.

If you calibrate whilst on or near metal objects it could screw up the compass for the flight.

 

[KostasNK]

I'll pretend I didn't see the 700m bit

Why? He said away, not higher than the take off point...

 

[Joely-Bird]

Why? He said away, not higher than the take off point...

500m horizontally is considered the limit for VLOS... I'm not coming down any side of the argument here, just pointing out why Nigpd might be concerned.

 

[PM160Mavic]

I haven't done one yet. There isn't a need unless instructed to do so by the bird.

 

[nealh]

I'm interested to know if you do compass calibration before every take off or not.

Pro's/Cons?

What's your take on it?!

I seem to get the message to calibrate almost every time. I usually comply because it only takes a minute, and just in case. But I don't think that is needed every time, unless something out of the ordinary happens..
Good luck.

 

[Beemer533]

I think if you are getting a message to calibrate nearly everytime, you are either always trying to take from your grill or the hood of your car or something is wrong with the Mavic...

Is it just the status window that shows the state of everything when you first connect?

 

[BudWalker]

..... there was a bunch of steel girders under the concrete, that would be driving the compass nuts. In this situation, the compass will be fine once you get a few meters up in the air.
....

The real issue is the Flight Controller's value for Yaw. Shortly after the battery is turned on the FC sets the Yaw value from the magnetometers (compass). After that Yaw is derived mostly from the IMU; i.e the compass has only a small effect. So, if it's a situation where the Mavic is turned on while sitting on a manhole cover then the compass will recover after launch (because it clears the effects of the manhole cover. BUT, Yaw is still compromised. Many fly-aways have been caused by this situation.

The single most effective check to prevent a fly away at launch is to make sure the heading indicator in the Go App is correct. This triangle represents Yaw value being used by the FC.

Suppose Mavic is turned on while sitting on a manhole cover and then moved to a site that isn't geomagnetically distorted. In this case the Yaw value will gradually change to reflect the now correct compass value. The is because of the small influence of the compass. If you look at the Go App you can see the red triangle change. When it's correct then it's OK to launch.

Now suppose the Mavic is turned on at a site that isn't geomagnetically distorted and then moved to the manhole cover for launch. If launch is immediate the Yaw value will be close enough to correct that there won't be a problem. Again, check the Yaw value presented by the Go App.

 

[Joely-Bird]

@BudWalker Thanks for the helpful explanation. It seems I misunderstood what was really happening during flight, apologies to all for dishing out bad advice.

I'll be sure to double check the heading in future! usually, I look at the home position pretty carefully esp if taking off near water/obstacles, but hadn't considered that the heading might be off so never paid attention to it!

 

[Nigpd]

Why? He said away, not higher than the take off point...

CAA guidlines are max flight distance 500m away from take off point

 

[mavic6611]

The real issue is the Flight Controller's value for Yaw. Shortly after the battery is turned on the FC sets the Yaw value from the magnetometers (compass). After that Yaw is derived mostly from the IMU; i.e the compass has only a small effect. So, if it's a situation where the Mavic is turned on while sitting on a manhole cover then the compass will recover after launch (because it clears the effects of the manhole cover. BUT, Yaw is still compromised. Many fly-aways have been caused by this situation.

The single most effective check to prevent a fly away at launch is to make sure the heading indicator in the Go App is correct. This triangle represents Yaw value being used by the FC.
View attachment 16627
Suppose Mavic is turned on while sitting on a manhole cover and then moved to a site that isn't geomagnetically distorted. In this case the Yaw value will gradually change to reflect the now correct compass value. The is because of the small influence of the compass. If you look at the Go App you can see the red triangle change. When it's correct then it's OK to launch.

Now suppose the Mavic is turned on at a site that isn't geomagnetically distorted and then moved to the manhole cover for launch. If launch is immediate the Yaw value will be close enough to correct that there won't be a problem. Again, check the Yaw value presented by the Go App.

Probably the best and logical explanation I've heard.
Great way to explain, alot of people who read this will learn from it.

Thanks mate.

 

[Nigpd]

Probably the best and logical explanation I've heard.
Great way to explain, alot of people who read this will learn from it.

Thanks mate.

Ageed

 

[Capt. Jim Ferman]

Are you

Are you sure it's telling you to calibrate? Or are you just simply seeing the calibrate button?

Have you tried doing an IMU calibration Jim? That solves most issues. You should try that. It's likely that will cure the problem.

When I start up my Mavic a window comes up confirming that I have the latest firmware and a little farther down the screen it shows the word calibrate with a box around it. (Thanks for your reply)

 

[BossBob]

When I start up my Mavic a window comes up confirming that I have the latest firmware and a little farther down the screen it shows the word calibrate with a box around it. (Thanks for your reply)

You are seeing the calibrate button that takes you to the calibration routine. I've seen that button ever since my Mavic arrived and never done a calibration. I've never had any problems.

 

[Flycaster]

Not once since opening the boxes.
I always check the sensor states, and always happy!
Once, as a test, I was trying to powerup, and take of, got the compass issue notification,
moved the Savy Mavy 5 feet from a car, and all was happy.

 

[ivor4000]

I'm in the UK and the app is 9 times out of 10 asking for calibration of the compass.

 

[dsd317]

I've been flying my Mavic all around Texas since November 2016 and have NOT performed a single compass calibration at all...even while flying in Hawaii.

 

[MavicMo]

I only do CC when the app tells me to OR I notice the Mavic is drifting...

 

[wolfmad]

Nope

 

[jwjonesjr]

It seems no one does a preflight before launch. Should do a compass calibration before each flight in a new location.

 

[flyaway]

I only calibrate when the app prompts me that it needs calibration