Flyway! Technical reason

alirz · Feb 7, 2016

So I know and have read about flyaway a for a long time now for the p3... As rare as they might be.
Do we know what's the technical reason/fault that causes a fly away.?
What coordinates or whatever does the phantom fly towards during a fly away?
Is it random,garbage goes coordinates?
Is it Compass calibration error, interference that makes it think it needs to be some here else?
It it a RTH auto Trigger towards incorrect/garbage home point coordinates?

Those are points I can think off.. I mean the phantom has to fly towards something or to some coordinates during a fly away. It can't be a rand on direction with no destination........

With The Birds · Feb 8, 2016

From what i have read in the absence of confirmed mechanical/electrical failure which would include compass calibration but also improperly installed prop, esc/motor etc it is usually pilot error/judgement. Including loss of GPS lock or unexpected behaviour in autonomous flight modes and not knowing how to fly manually. Im not being critical, i have had my fair share of incidents with all sorts of RC flying things.

alokbhargava · Feb 8, 2016

A simple explanation to understand: P3 stores the home point and to return it back, it calculates the direction based on its current position and then start moving into that direction based on the direction given by the compass. Any error into direction takes it away to another location. This process is repeated from the next point reached to home point and thus is a self correcting for minor compass/ computational errors.

ELHEAPO · Feb 8, 2016

Why do so many people rely on RTH function, if you fly line of sight you should never need it, dont get me wrong its an interesting feature but I think if you fly distance and rely on the RTH you are always taking a slight chance of it not coming back...it aint no boomerang!!

Erroll · Feb 8, 2016

ELHEAPO said:
Why do so many people rely on RTH function, if you fly line of sight you should never need it, dont get me wrong its an interesting feature but I think if you fly distance and rely on the RTH you are always taking a slight chance of it not coming back...it aint no boomerang!!

Why do so many people rely on the airbags in their cars? If you drive carefully, never exceed the speed limit and stop at red lights and stop streets, you shouldn't need airbags.

I do a lot of distance flying (see HD link below). I know and understand the risks, but I do not rely on RTH. I have had RTH invoke on more than one occasion, and I was glad it worked. The day I need it again and it doesn't work will be a sad (and expensive) day indeed. I'll get over it.

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With The Birds · Feb 8, 2016

ELHEAPO said:
Why do so many people rely on RTH function, if you fly line of sight you should never need it, dont get me wrong its an interesting feature but I think if you fly distance and rely on the RTH you are always taking a slight chance of it not coming back...it aint no boomerang!!

Agreed however the op mentioned

ELHEAPO said:
Why do so many people rely on RTH function, if you fly line of sight you should never need it, dont get me wrong its an interesting feature but I think if you fly distance and rely on the RTH you are always taking a slight chance of it not coming back...it aint no boomerang!!

Agreed however the OP mentioned "auto return to home". Dont know about you but i really want that one to work and l will happily rely on it... saved me when i flew behind a headland... I let it do its ascent at which time i had a solid connection again where i cancelled and continued to fly.

RoyVa · Feb 8, 2016

You definately want home lock before you fly. Just when you think you are the best in the west... You'll find out you wished you had it. Even the best experienced and careful fliers end up with "Lost Contact, returning home" once in a while. Saves your loosing $$$$ for sure.

ELHEAPO · Feb 8, 2016

Erroll said:
Why do so many people rely on the airbags in their cars? If you drive carefully, never exceed the speed limit and stop at red lights and stop streets, you shouldn't need airbags.

I do a lot of distance flying (see HD link below). I know and understand the risks, but I do not rely on RTH. I have had RTH invoke on more than one occasion, and I was glad it worked. The day I need it again and it doesn't work will be a sad (and expensive) day indeed. I'll get over it.

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I understand the point you make but i think a lot of fly aways are more human error than technical fault but as you said its a expensive risk you take when doing long distance flying!The key with a lot of RTH failures is probably a bad compass calibration in the first place.

Erroll · Feb 8, 2016

ELHEAPO said:
....but i think a lot of fly aways are more human error than technical fault..........

I believe that is the important distinction, and on top of that, from what I see here, it is almost the culture to first blame DJI, and see if a free warranty replacement can be had.

I am down here in South Africa, where it is not practical to quickly DHL my quad to DJI for repairs, meaning a two or three month run-around. That is one of the reasons why I do a lot of pre-mission work, such as ensuring proper calibration, route checking, weather and wind checking, elevation checking, waypoint checking, and rechecking all of the above. While the mission is underway I constantly monitor my battery and other telemetry, my finger is on the P-switch all the way, I scan the horison all the time.

There is a thread on here where the pilot was sure that the quad's compass 'malfunctioned' as a result of power lines or some such, while he had in fact accidentally planned his Litchi mission to drop from 100 foot to 15 foot between two waypoints, with trees in between.

We all make mistakes. When Litchi waypoints first became available on iOS, I set up a few missions in my neigbourhood using the web. I went to my big local park, accidentally selected a mission designed for a different park and launched it. The quad made a bee-line for the second park, but because I had my finger on the P-switch I was able to abandon the mission before any damage ensued! It would have been easy to blame Litchi or DJI's firmware, or sunspots or DemunSeed, and attempt a warranty claim.....

Finally, the risk is not only in long distance. These machines are full of very complex electronics. Electronics can fail, whether you are 5 or 5000 meters out. The best a responsible PIC can do is understand this, train for it, prepare for it, and do everything you can to mitigate the risk.
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alirz · Feb 8, 2016

Thanks all. My question was more to inquire about, what's the technical reason that causes a fly away. From what I've read, for those who've experienced a fly away was something like this.
They were flying the p3 relatively close to them let's say maybe a few hundred feet away, in LOS, where suddenly the p3 just took off in a random direction for no reason...

What would cause that..

RoyVa · Feb 8, 2016

If you study a lot of the fly a way you will find no common denominator except the quad itself. And what I mean by that is its internal functions. I have come to think that the sytem reboots its self and when it does it's just like a computer. Anything that you were working on is lost. It's random access memory was erased and in the case of the quad its erasure would be the GPS cordinances its home point and now it has no information as to where or what to do hence a fly a way. This does t happen often but when it does it can be catastrophic.
The Phantom is all electronics and basically computer controlled. Same as if you were in a new city driving only on GPS and it turned off. Then what happens..... Your lost and you can go in any direction but your still lost. Just my two cents.