Phantom 4 RTH Crash! (Obstacle Sensing)

levancuthbert · May 29, 2016

Hey everyone! I'm an Inspire flyer, but just bought a new Phantom 4 a couple days ago. I'm in Atlanta this weekend visiting family, and was flying around a park downtown to get some neat shots of the skyline. As I was flying between 2 buildings, the Phantom lost connection with the RC, and the video image on the screen went black. It popped up to activate RTH, but still no image. Around 10-15 seconds into its auto RTH flight, the video image flashed on the screen for about a second or 2, and I see that it's about 5-10 feet from hitting the building! I immediately tried to turn it left to avoid impact, and the screen went black again. Then shortly after, it showed Aircraft Disconnected. I'm assuming it hit the building and crashed. I did have the obstacle avoidance setting ON, so I have no idea how it didn't detect the building and avoid it. The building has another attached level which I believe it landed on, so I wasn't able to retrieve it. Since its Memorial Day weekend and the building isn't open, I'm going to try to figure out a way to get it before I have to drive back to Indiana.

So, I'm looking for opinions about why you all think it didn't avoid the building, and whether this is something DJI may possibly cover (even if I'm not able to retrieve the aircraft itself). I have the flight records showing all of this. Thank you for any input!

Chopstix Kid · May 30, 2016

It's possible that the bird lost GPS signals as well. I'm not certain what that would result in but RTH is dependent on GPS. What altitude were you flying? I think the default RTH alt is 30m so if you were higher than that, no issue there but if you were lower, the bird will gain alt till it reaches the RTH alt... and it will hit anything that may be above it. Did you happen to notice the obstacle sensing warning bars on your display? I'm new at all this too but I've been following enough threads to know that these are all the things (plus more) that people will ask.

Fallguy · May 30, 2016

Flying in downtown Atlanta between buildings ? Not a smart choice. Too many things could happen , and most are bad. Your lucky you didn't hurt someone flying over city streets blind. Not trying to preach to you , but "come on man."

Mark Granger · May 30, 2016

Another DJI drone that would have been saved if DJI implemented return along path for about 100 meters to put the drone back in signal range rather than make a beeline to home through the object that blocked the signal. RTH was a cool feature two years ago but now days it seems like the dumbest thing ever.

cokeaddict · May 30, 2016

Great idea Mark. Yes Return via path sounds perfect but sadly I don't think it would solve issues, especially if the bird has been flying for 20 minutes then decided to RTH, it would have to re trace the 20 minute flight before getting back to its launch site. Would be fantastic if they could find a way to get the bird back to the point of take off as quick as possible using the same path you suggested without having to do the full 20 minute flight .

Dirty Bird · May 30, 2016

RTH is great but it does require a bit of due diligence on the pilot's part to ensure it functions properly. Primarily all that is required is verifying & setting your RTH altitude to clear any obstacles. Also many pilots do foolish things without considering the ramifications....like flying around the back side of a 500' building with the RTH set for 100'. It's cool to attempt to fly behind the obstacle as long as you have set RTH accordingly in case of signal loss. The default 30m RTH setting is simply too low in many instances. Setting it for 100-130m would be a wiser default though those flying in urban & mountainous terrain may need to adjust up accordingly.

Mark Granger said:
Another DJI drone that would have been saved if DJI implemented return along path for about 100 meters to put the drone back in signal range rather than make a beeline to home through the object that blocked the signal. RTH was a cool feature two years ago but now days it seems like the dumbest thing ever.

Mark Granger · May 30, 2016

cokeaddict said:
Great idea Mark. Yes Return via path sounds perfect but sadly I don't think it would solve issues, especially if the bird has been flying for 20 minutes then decided to RTH, it would have to re trace the 20 minute flight before getting back to its launch site. Would be fantastic if they could find a way to get the bird back to the point of take off as quick as possible using the same path you suggested without having to do the full 20 minute flight .

Nope. Every time I suggest this idea someone comes up with this reason why it won't work. That's why I said it should retrace its path about 100 meters (perhaps some user option like RTH altitude) to allow you to get the drone back under control before making a beeline for the home point. This would get the drone back under control about 99 times out of 100.