My first flyaway! What did I do wrong?

[Jeff watson]

I had a recent fly away. I just reviewed the log this morning. I calibrated the compass for the area. I got up to 20 feet and hovered. Sent the bird out and turned toward a big hill. I lost GPS signal and was flying into the hill at 15 mph. I tried to use the controls and resorted to RTH. I heard the control say RTH activated. The copter turned toward home and travelled a few feet and stopped. I then had a camera view and since it was hovering, continued flying. I was told there are magnetic fields over in those mountains. Maybe that's what happened. I don't know.


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[flyNfrank]

What does A/C stand for?

A/C= AirCraft
R/C= Remote Controller

 

[skipilot1]

A/C= AirCraft
R/C= Remote Controller

I get the RC. I just always referred to the AC as the bird or the drone. Now I know.

 

[flyNfrank]

I used to calibrate often, if I changed location I calibrated. That stopped when I had a problem that resulted in a compass error. Fortunately for me, I knew what to do and I recovered the bird without much butt puckering... The problem was absolutely because I calibrated in a bad spot. I now follow the directions from the primer thread. I have 300 miles flown and no real issues since. I can vouch that calibrating too often increases the chance of introducing a bad calibration. I'm in the camp of lock it in and do not change it unless their is something of significance occurs warranting a new calibration.


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Sounds more like you were not sure of the compass calibration process. If you're in a bad spot, or do the process out of spec in some manner, it will not give you the successfully completed flashing green light.

Btw, the compass issue itself seems to appear the most with those that use the app's Auto Takeoff feature. It is the app that sends the commands. It's like the app doesn't wait to receive confirmation from the 1st command from the A/C before sending additional commands. Like in this situation here, it sends this same warning message out every other second for 5 times in a row "Warning:Satellite Positioning Off. Fly with caution".

Then it's also commanding RTH, along with Auto Land, plus more.

 

[flyNfrank]

I get the RC. I just always referred to the AC as the bird or the drone. Now I know.

There was a time when the reference "drone" was a bad word with several members on here. We were trying to figure out why so many people had bad vibes about multicopters in general. I gave the reason that people hear the national news give reference to the government drones that spy and have guns attached, ect. And from that look at what we fly as being able to do the same type of spying and what not.

 

[Susruth]

There was a time when the reference "drone" was a bad word with several members on here. We were trying to figure out why so many people had bad vibes about multicopters in general. I gave the reason that people hear the national news give reference to the government drones that spy and have guns attached, ect. And from that look at what we fly as being able to do the same type of spying and what not.

And drones being paparazzi too

 

[qrandle]

@flyNfrank, I appreciate the Refernce to the solid green lifht. But I was doing a calibration and got the solid green light halfway through the second rotation when the A/C is sideways so to speak. I was basically still holding it in the air bringing it to the ground with a solid green and then I get the blinking green.

So that's why I get a bit confused when you state to wait for the solid green light. For me the solid green light seems to happen really fast before I even realize it.

Anyway, just trying to make sure I understand the process completely.

Q

 

[flyNfrank]

@flyNfrank, I appreciate the Refernce to the solid green lifht. But I was doing a calibration and got the solid green light halfway through the second rotation when the A/C is sideways so to speak. I was basically still holding it in the air bringing it to the ground with a solid green and then I get the blinking green.

So that's why I get a bit confused when you state to wait for the solid green light. For me the solid green light seems to happen really fast before I even realize it.

Anyway, just trying to make sure I understand the process completely.

Q

The solid green light needs to take place at the end of a 360 degree (full) turn. The blinking green light has to do with receiving the required number of satellite signals. If the volume is up on your device at this point you might also hear it say home point has been recorded and ready for flight.

 

[RocketBrew]

I only calibrate after a firmware upgrade.
Took my P3P to CA - over 400 mi. away (as the drone flies) - and flew it several times without calibrating, then another 50+ miles to San Clemente for some beach footage. Back in Tucson continued to fly calibrating, including a 2.6 mile flight across the desert. No errors or problems.

 

[rdandy5875]

Only thing I have to add is make sure you don't have a steel watch on (or similar) when doing the calibration. My SS watch (diver with SS bracelet as well) messed up the compass calibration a couple times before I knew better.

In fact after I got a good compass calibration I haven't done it again in about a dozen flights. Good to know about the 100+ mile, re-calibrate, though. Makes sense.

Good luck with the re-cal...Glad you got it back in one piece.

 

[flyNfrank]

I only calibrate after a firmware upgrade.
Took my P3P to CA - over 400 mi. away (as the drone flies) - and flew it several times without calibrating, then another 50+ miles to San Clemente for some beach footage. Back in Tucson continued to fly calibrating, including a 2.6 mile flight across the desert. No errors or problems.

I wouldn't be bragging about that kind of carelessness. That's like Russian roulette.

 

[qrandle]

The solid green light needs to take place at the end of a 360 degree (full) turn. The blinking green light has to do with receiving the required number of satellite signals. If the volume is up on your device at this point you might also hear it say home point has been recorded and ready for flight.

I think that's basically when it is occurring I believe; so what is the purpose of the second full 360 where you are holding it vertically?

 

[jaseman007]

I've never really got the theory of performing a compass calibration before every flight. Since my first compass calibration my home point is successfully recorded before each flight. My thoughts would be that if your home point doesn't record correctly then calibrate otherwise she's good to go.

 

[flyNfrank]

I think that's basically when it is occurring I believe; so what is the purpose of the second full 360 where you are holding it vertically?

I don't know the answer to that. I do know there is a gyro involved which data does get recorded for it. Keep in mind the A/C logs the flight pitch, the flight roll, and the yaw. If I had to guess, the vertical calibration is related to these I just mentioned.

I've never really got the theory of performing a compass calibration before every flight. Since my first compass calibration my home point is successfully recorded before each flight. My thoughts would be that if your home point doesn't record correctly then calibrate otherwise she's good to go.

Ok so....to begin with, the compass calibration is NO theory. If you were to consider yourself as a regular follower of this forum, I would think that based on the threads created compass calibrations would be common sense. If you were to ask each of those that has either lost or crashed who posted a thread such as this one we're posting in here, you will find the number of those that did NOT calibrate prior to the issue,....that number will far exceed those that do calibrate. Regardless what any other person that follow behind this post may say about calibrating, just ask those with a loss if they did or did not properly calibrate before hand. Btw, just so you know, compass calibrations are logged in the flight log.

Your Home Point is recorded only based on the Longitude & Latitude. The compass has nothing to do with Home Point.

I was a dji P3 and GO app beta tester until I decided to take a break. And the tech developers said calibrating before each flight was a process that should be done before every flight. There were those that asked for a more detailed response on why it should be done, and they questions were ignored/unanswered.

 

[FantomFlier]

There were those that asked for a more detailed response on why it should be done, and they questions were ignored/unanswered.

That is most likely because there is no sound technical reason for calibrating before every flight.

DJI does also recommends that you do not fly over water. What possible sound, technical reason could there be?

CYA.

Frank, you are entitled to be conservative in your approach to looking after your quad, and all power to you, but that doesn't make everyone else who differs wrong.

I am absolutely convinced that by far the greatest majority of Phantom 3 pilots do not calibrate before every flight, with no ill effects.

 

[Vertigo]

The "calibrating before every flight" doesnt make a lot of sense to me. Unless you travel a few 1000 Km between flights, or dont fly for weeks, then whatever you think could change in the magnetic field between 2 flights could just as well change during a flight, especially a long distance one. I also fly full scale planes, and do you know how often we calibrate electronic compass on those? Never. But they calibrate themselves during flight, and if you read the phantom 3 manual carefully, it would seem the phantom does too when you get the '"Compass error, exiting P-GPS mode" message AND you are high enough (not specified) with good GPS reception. See my post here:

HELP! P3 Professional went out of control and crashed.

The manual is very vague and no one seems to know exactly how this procedure is supposed to work. I know how it works on some other non DJI flight controllers like the pixhawk, where ground track is calculated from GPS position and used to slowly adjust magnetic offsets.

My current theory is that when you get the "Compass error, exiting P-GPS mode", the phantom does just the same thing, as mentioned in the manual, just not as gracefully as the pixhawk, and while the process is under way, a process that may involve yawing the quad and tilting it in various directions to get all the needed data, the quad appears out of control. And I guess, pretty much is out of control of the pilot, but it just needs to travel enough distance to calculate headings accurately to adjust the magnetic offsets.

If this is true, then I do not understand why on earth this procedure isnt explained in more detail and why the hell its not aborted if you switch to attitude mode. A mode in which you shouldnt need valid compass data or even a compass to have a perfectly flyable quad. To be clear, you did manually switch the RC to attitude mode, correct?

 

[With The Birds]

I don't know the answer to that. I do know there is a gyro involved which data does get recorded for it. Keep in mind the A/C logs the flight pitch, the flight roll, and the yaw. If I had to guess, the vertical calibration is related to these I just mentioned.



Ok so....to begin with, the compass calibration is NO theory. If you were to consider yourself as a regular follower of this forum, I would think that based on the threads created compass calibrations would be common sense. If you were to ask each of those that has either lost or crashed who posted a thread such as this one we're posting in here, you will find the number of those that did NOT calibrate prior to the issue,....that number will far exceed those that do calibrate. Regardless what any other person that follow behind this post may say about calibrating, just ask those with a loss if they did or did not properly calibrate before hand. Btw, just so you know, compass calibrations are logged in the flight log.

Your Home Point is recorded only based on the Longitude & Latitude. The compass has nothing to do with Home Point.

I was a dji P3 and GO app beta tester until I decided to take a break. And the tech developers said calibrating before each flight was a process that should be done before every flight. There were those that asked for a more detailed response on why it should be done, and they questions were ignored/unanswered.

Each to their own. Personally i am more comfortable with flying my known good calibration within 100 miles of where it was performed.

The only issues i have had compass related were in the early flights where i was calibrating at every new location. Early days and getting used to flying the phantom these new locations were in areas where there were often contributing factors, the most notable being a calibration i performed near an astro turf cricket pitch. Yes, the turf was laid over concrete which almost certainly contained steel reinforcing and in hindsight was seen by the phantom as a giant bar magnet. That was a white nuckle flight, the phantom behaved unpredictably everwhere except close in to where i performed the calibration. That was an education for me.

As to compass related crash threads my sense is there are as many if not more where the compass was calibrated pre flight.

If the mod values look good im flying on the last known good calibration.

 

[Mimoid]

After seeing this in more then one of your post, you seriously need bring yourself up to speed on doing compass calibrations. You mention having compass issues multiple times(more then once) and this really needs to be taken seriously. I calibrate the compass before every flight and I never have to redo or question any of them.

Treat the calibration process with respect. As in keep the aircraft level, and don't do the process too fast.

Do not, I repeat, do NOT calibrate your compass before every flight. Or by all means, do it, but understand what you are doing.

You need to understand what a compass calibration does. It measures Earh's geomagnetic field, and registers both the local differences as well as any magnetic anomalies near the aircraft. This data is then stored and used to calculate the directional movement and orientation of the aircraft in flight.

After a good calibration, the Phantom is perfectly calibrated for your generic geographical location. Since Earth's magnetic field will not change radically over the short time span of a few months, it's a one-time activity. Unless you are travelling hundreds of km's, where the geomagnetic field is different, or if you have not calibrated in six months or so, you don't need to do it again.

The problem with frequent recalibration is that every new calibration increases the risk for bad or incorrect compass offset data to be stored, which might lead to more or less serious navigation errors.

The first flight after a compass calibration should be regarded as a controlled test flight to find potential compass related navigation errors. You should be prepared for strange behavior, like inability to hold position or camera tilt during turns, and in that case switch to Atti mode and land immediately.

Needless to say, if you are recalibrating before every flight, you are pretty much only doing test flights.

// Tom

 

[FrequentFlyer]

I've never really got the theory of performing a compass calibration before every flight. Since my first compass calibration my home point is successfully recorded before each flight. My thoughts would be that if your home point doesn't record correctly then calibrate otherwise she's good to go.

Recording the home point is a function if the GPS and has nothing to do with the compass or compass calibration.


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[flyNfrank]

Everyone is entitled to their opinion. Sometimes some do not respect others. I have not told anyone they were wrong for not pre-calibrating. I have pointed out the numbers in failures between those that have, and have not. And that is a fact.

Calibrating one time based on location is how it SHOULD actually take place. But, for whatever reason it seems there is not a 100% guarantee the info on that calibration remains forever locked with in the P3. Or, it does stay with the aircraft, but possibly it's the App that causes the confusion every once in a great while. I feel like the calibrating I do before each flight reminds all aspects of the P3 just what those settings are.