First close call with Phantom 3 Pro

[denodan]

I always calibrate my compass but today almost found out first hand what could happen. Taking off from the same spot as last time and didn't calibrate. Auto-takeoff and within seconds I sense something is wrong. My indicators have satellites I got the safe to fly go-ahead, but no good. Phantom is drifting in air and my weak manual skills had to be used to land her. Find a patch of grass close to a metal fence, land right beside the fence with the winds blowing me around, safely landed but my propellers sliced the fence and broke. She didn't even tip over just propeller damage. Replaced and calibrated. Next flight was as smooth as always.

Just a heads up, always calibrate your goods.

I have never had issues. Had a phantom 1 since they first came out only calibrated once.

My Phantom 2+ have had around 70 flights only calibrated once, no issues

And 40 flights on th p3 only calibrated once no issues.

You may have been near a metal surface or underground metal pipes could have caused an issue. Calibrating to much can be a bad idea also as its still possible to get a bad compass calibration. The more you do this, the greater the risk of a bad calibration.

All that will happen is it will toilet bowl and can control it and land easy, and taking off you will know in less than 1 minute it's not right.

 

[edonovanl]

P-ATTI - explains the drift.

Agree!

 

[ScottyT]

I think we know what it is now. It was gps. Strange but it is what it is.

Out of interest where were you flying to lose GPS signal? How many GPS Sats do you normally get?

I had a glitch like that once and I'm sure I got a message on my screen - at least I remember it being fairly obvious.

 

[Dome]

I faced something similar few days ago during tracking, with a flight in high mountain, no wind. First battery with all calibration done was a wonderful flight. I landed it, I switched off and change battery. But when take off again I immediately realize that something was wrong and weird drifting. I hand catch the bird, so no damage. Switched off and on again, this time everything went fine. Mhhh... The sats where ok, p-gps activated. No explanation, except that probably the system boot didn't go as expected. Rebooting again it worked fine.

 

[phantomized]

I had 11 or 12 satellites right before take off. It was semi-cloudy. It all happened so fast I didn't have much time to react as I was so low to the ground, about 6 feet or so. I did have control but I didn't want to take it any higher (I went up to 20 something feet max) and risk a flyaway or a bad crash in to an apartment building so I came down ASAP. I think I just need to be more observant on take off and not automatically assume gps will work all the time, this way I could have saved my 2 propellers. I am happy with my landing and no damage to the birds shell/camera at all.

 

[AHill]

I faced something similar few days ago during tracking, with a flight in high mountain, no wind. First battery with all calibration done was a wonderful flight. I landed it, I switched off and change battery. But when take off again I immediately realize that something was wrong and weird drifting. I hand catch the bird, so no damage. Switched off and on again, this time everything went fine. Mhhh... The sats where ok, p-gps activated. No explanation, except that probably the system boot didn't go as expected. Rebooting again it worked fine.

Had same thing happen. Did compass cal., ran two batteries to about 50%. Took off with third battery after getting ok to fly, was drifting and had toilet bowl effect so I landed it. Shut off and restarted, all was ok for last flight (didn't redo compass cal.). Always let it hover for a short time after taking off to verify all is working ok.

 

[F6Rider]

Practice flying in ATTI!!!, every pilot should do a lot of this, because at some point you are going to need it. As soon as I read 'I had 11 Sats, and 'Drifting with the wind' I thought ATTI mode. I always get 15-20 Sats almost at once, 11 is iffy and you need to be ready for ATTI because it will shift into it when it hits 7 sats. I fly at least one entire battery in ATTI mode once a week or so, did it with my P2 also, don't rely solely on GPS, kind of like practicing non-standards, you hope you won't need the skills but you better have them.

 

[phantomized]

Practice flying in ATTI!!!, every pilot should do a lot of this, because at some point you are going to need it. As soon as I read 'I had 11 Sats, and 'Drifting with the wind' I thought ATTI mode. I always get 15-20 Sats almost at once, 11 is iffy and you need to be ready for ATTI because it will shift into it when it hits 7 sats. I fly at least one entire battery in ATTI mode once a week or so, did it with my P2 also, don't rely solely on GPS, kind of like practicing non-standards, you hope you won't need the skills but you better have them.

Yes for sure ATTI would be really good to master. I am just okay because I use to fly a WL Toys quad and it is very difficult to control. I don't want to practice ATTI with the Phantom so I should probably practice more with the wltoys. Thanks for advice.

 

[phantomized]

I think we know what it is now. It was gps. Strange but it is what it is.

In this pic it says my height is -9.8 feet. How is this possible? I didn't take off from a higher elevation.

 

[F6Rider]

In this pic it says my height is -9.8 feet. How is this possible? I didn't take off from a higher elevation.

Bad GPS signal will do that, do you have VPS turned off?, if not you might have been at 10' or so, where VPS turns off.

 

[Dave Ward]

Something like that happened with my P3P a few days ago. I took off from a wooden observation deck, in the middle of nature. No metal or strong interference around. 10+ satellites the entire time.

Just after takeoff, it immediately veered right as sharply as if I had given it a full-right input on the tx. I countered with full left, but it went back right each time I let off the left input. After several seconds of fighting (which felt like hours at the time), it just stopped and started flying perfectly normal.

The whole ordeal ended up being a good thing, because some birds came out of the trees at about the same time that the Phantom started acting crazy. Normally, I bring it down whenever I see birds, but the erratic behavior seemed to scare them away and I was able to complete my flight without any more trouble.

I can see how this is leading to crashes though. If I had been in my back yard when this happened, it would have been plastered against a fence or my neighbor's house before I could get control back.

 

[snowghost]

Something like that happened with my P3P a few days ago. I took off from a wooden observation deck, in the middle of nature. No metal or strong interference around. 10+ satellites the entire time.

Just after takeoff, it immediately veered right as sharply as if I had given it a full-right input on the tx. I countered with full left, but it went back right each time I let off the left input. After several seconds of fighting (which felt like hours at the time), it just stopped and started flying perfectly normal.

The whole ordeal ended up being a good thing, because some birds came out of the trees at about the same time that the Phantom started acting crazy. Normally, I bring it down whenever I see birds, but the erratic behavior seemed to scare them away and I was able to complete my flight without any more trouble.

I can see how this is leading to crashes though. If I had been in my back yard when this happened, it would have been plastered against a fence or my neighbor's house before I could get control back.

Did you try switching to Atti Mode to get control?

 

[Dave Ward]

Did you try switching to Atti Mode to get control?

I probably should have, but was focused on doing what was working and didn't think about that until later.

 

[phantomized]

Out of interest where were you flying to lose GPS signal? How many GPS Sats do you normally get?

I had a glitch like that once and I'm sure I got a message on my screen - at least I remember it being fairly obvious.

I was flying out from a parking lot between a few apartment buildings, usually I get about 11 or 12 sats at take off and when I get higher up I'm 15+. After reviewing my replay it looks like I didn't get any warnings until a couple seconds before I landed it went in to ATTI mode.

 

[eseckinger]

Lost GPS, nothing to do with calibration here OP. please understand this so you do not confuse people.

 

[phantomized]

Lost GPS, nothing to do with calibration here OP. please understand this so you do not confuse people.

I understand this now. I have updated the original post with a NOTE informing folks.

 

[Dome]

Practice flying in ATTI!!!, every pilot should do a lot of this, because at some point you are going to need it. As soon as I read 'I had 11 Sats, and 'Drifting with the wind' I thought ATTI mode. I always get 15-20 Sats almost at once, 11 is iffy and you need to be ready for ATTI because it will shift into it when it hits 7 sats. I fly at least one entire battery in ATTI mode once a week or so, did it with my P2 also, don't rely solely on GPS, kind of like practicing non-standards, you hope you won't need the skills but you better have them.

Yes, this is a right suggestion and I switched it to atti mode immediately and I drove it down. But also in atti it was quite uncontrollable. I fill very lucky to catch it without damages (me and p3) ..
When on the ground and switched off motors, I looked at sensors parameters and nothing was wrong: IMU ok, compass ok, GPS ok, sticks ok. This is scaring!

 

[F6Rider]

Yes, this is a right suggestion and I switched it to atti mode immediately and I drove it down. But also in atti it was quite uncontrollable. I fill very lucky to catch it without damages (me and p3) ..
When on the ground and switched off motors, I looked at sensors parameters and nothing was wrong: IMU ok, compass ok, GPS ok, sticks ok. This is scaring!

You must remember that in ATTI every motion requires a counter motion. Once you have it moving in one direction centering the sticks WILL NOT stop it, it will continue in that direction until you apple equal and opposite control inputs. So it might feel out of control compared to GPS mode but it is not. That is why it drifted with the wind, think of it as a balloon that you must control against the wind. Takes a little practice in LIGHT winds but it will make you a much better pilot.

 

[Bret Lucas]

Understanding when to calibrate is vital.

When Should I Calibrate?

You do not need to calibrate before every flight and in some cases you definitely should not calibrate. That doesn't mean you shouldn't ever bother doing it. It only takes one time for it to go very wrong. The most important aspect of compass calibration is making sure the magnetic "noise" around your Phantom is consistent between calibration and during flight.

DO Calibrate
If you go to a new location that is a good distance (i.e. >100 miles) from the last place you calibrated the compass.
If the terrain has changed significantly i.e. going from prairie to mountainous.
If you change any equipment on your Phantom.
If you just installed new firmware.
If you just degaussed your compass (BTW, don't degauss unless you are absolutely positively sure you need to).
If you have taken all the precautions to make sure there are no localized magnetic fields near you.

DO NOT Calibrate
If you're in an urban area surrounded by concrete, buildings, and hidden or overhead power lines / pipes / etc.
If you're on the beach or on a boat.
If you're in immediate proximity to metallic objects or anything magnetic.

 

[snowghost]

You must remember that in ATTI every motion requires a counter motion. Once you have it moving in one direction centering the sticks WILL NOT stop it, it will continue in that direction until you apple equal and opposite control inputs. So it might feel out of control compared to GPS mode but it is not. That is why it drifted with the wind, think of it as a balloon that you must control against the wind. Takes a little practice in LIGHT winds but it will make you a much better pilot.

Yes, or get a toy one like the X5C and practice in light winds--or even no wind.