I am now in to week 9 since my fly away. A resolution is near with a replacement bird on its way to Oz. I was hoping for some answers from DJI after their inspection of my destroyed Inspire but have got nothing so far. I have asked this question to quite a few people in Oz and no one can answer it so I am hoping some one out there can.
The MILLION DOLLAR QUESTION>>>>>>>

You are flying in ATTI with NO GPS (ie. inside) and an RC SIGNAL failure occurs.......what is the bird going to do?

Points to note:


>  There is NO GPS so it does not know where it is
>  If it is launched without GPS so NO home point is recorded.
>  Previous home point is cleared with a power cycle from what have been told so it won't go there.

I have been asking DJI these questions since the fly away as this is a similar situation as to what occured to me except that it occured outside. Fault analysis from DJI indicated failed GPS module. RC signal failure occured with it a few metres in front of me, it then took off to god knows where at full power until it hit a big tree.

Whilst I am happy DJI eventually replaced my bird, I am eager to know the answer to what happened and have a thorough understanding of what would occur in this situation. The answer will make us all a little more informed.

Any thoughts would be appreciated, a response from an expert at DJI would be even better!

I am not an expert but I will conjecture.

First, you mention "inside" but then refer to a "big tree."  If you were inside, and there was sufficient detail in the floor (i.e. not a featureless surface) it may be able to use its visual positioning hardware to hold position.  However if it is outside or at a greater altitude than workable for visual positioning, it SHOULD go into a hover.  Unlike a GPS-controlled hover, however, it would follow the air mass.  If there is no wind it should remain stationary.  If there's a 20 mile per hour wind it will move at 20 miles per hour in the direction of that wind.

With that said, there is another thread that commenced today in which the pilot lost the control signal while the Inspire was moving forward.  Instead of stopping and hovering, the aircraft continued under power until it struck a wall and was destroyed.  This sounds an awful lot like a serious bug and not the behavior that was intentionally designed into the system.  Everything I have heard/seen about the Inspire says that with a loss of radio control it should "stop," to the degree practical, in the air.

Excellent question.  Personally I would hope it would just beep and land.   If it's indoors chances are it's pretty close to you and you can try to catch it or at least clear a path.

If it hovers 15 feet off the ground then what?   Obviously try to reestablish connection but what if you can't?

Also, in my experience you don't have to be very high before the visual positioning stops being effective.

PeteGould Posted at 2015-5-13 10:49
I am not an expert but I will conjecture.

First, you mention "inside" but then refer to a "big tree ...

Hi Pete,

I am posing a theoretical situation replicating my experience. My fly away did occur outside. I was in atti due to NO GPS, Post flight log proved a failed GPS unit.

The question posed replicates my scenario - flight with no gps and you get an rc signal failure. Just seeing if anyone knows what the inspire should do in this situation.

When my rc signal failure occurred (with zero gps) it took off on me until hitting the tree. The scenario posed I believe would place the craft into a similar situation as to what occurred - no one seems to exactly know what the result will be

jimhare Posted at 2015-5-13 11:13
Excellent question.  Personally I would hope it would just beep and land.   If it's indoors chances  ...

Hi Jim,

thanks for your thoughts. Yes, you would hope that it would just hover. My concern is that my flight in atti with no GPS and then rc signal loss , the bird did not hover. Just trying to ascertain if my bird behaved in a way it shouldn't have OR it is a scenario that has not been planned for on the inspire

Wolfman Posted at 2015-5-15 05:53
Hi Jim,

thanks for your thoughts. Yes, you would hope that it would just hover. My concern is tha ...

I would have thought that with no GPS, loss of RC signal and no RTH being set that the inspire may well hover but because there is no GPS it will drift with the wind and auto land when the battery is low provided it hasn't crashed into anything. Correct me if I'm wrong.

The OPTI mode has severe limitations. To my mind the ultrasonic sender and receiver should be separated much more than they are (say at opposite ends of the underside of the craft) so they have a greater bounce angle with the ground and with sufficient ultrasonic sender power the OPTI mode would work at greater heights and potentially be useful in holding the craft steady against the wind when there is a loss of GPS, no RC control and no RTH set. Still leaves the problem/dificulty of the craft finding (via ultrasound?) a clear landing area though.Thoughts?

gdc2510 Posted at 2015-5-15 07:58
I would have thought that with no GPS, loss of RC signal and no RTH being set that the inspire may ...

Hi GDC,

YES, I would hope that with no home point set, no gps then it would hover if rc signal loss occurs. This is the big question that still no one can categorically confirm.

CAN DJI PLEASE ADD THEIR INPUT to this question