RTH/Obstacle Avoidance
1293 8 2018-12-28
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Sato Zoom 2
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Flight distance : 3172890 ft
United States
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Had a near miss incident during a RTH procedure the other day.  The whole thing in hindsight could have been avoided if I had planned better ahead of time but the shoot was a spontaneous idea.  I’m doing a short circle POI video of a building that happened to be about 380’ tall with a radio like tower on top of it that extended well above 400’ AGL above that.  My M2Z is at or about preset max altitude (120m/397’ or so) barely above the “roof” of the building but well below the thin tower extending probably another 50’ upwards from there.
  
Big mistake, during the shoot I let the aircraft get behind the building placing the building between the transmitter and the craft, of course I started to lose signal and lost VLOS. The app asked me if I wanted to RTH for poor video signal and had I just barely clicked yes before it just went into total controller loss, aircraft completely disconnected.  So looking at the video later, it went to RTH but not FAILSAFE RTH due to controller loss where it should retrace it’s flight path backwards for a short period of time.  The M2 turned and made a straight line back to home with the tower right in the flight path. So not realizing this, I’m staring at a dead screen until reconnection is made and to my horror upon reconnection, I’m on a very short collision path with the tower on the top of the building.  Looking back on it, I could/should have just immediately hit the pause button, but in panic, I tried to steer away and of course had no directional control in RTH.  I held my breath and the M2 passed safely by but NARROWLY maybe within 5’ of the tower.  All of this happened within about 5 seconds.  It made for some unintentional but spectacular video.
  
  
Lots of lessons learned on this flight for me, mistakes I’ll never repeat, but here’s a real question that I can’t find an answer in the M2 manual.
  
  
Obstacle avoidance.  The manual says if an obstacle is detected on RTH, the craft will ascend until no obstacle is detected. What if it’s already at the max preset altitude limit during RTH?  Will it disobey that limit and ascend to avoid an obstacle or what will it do?  My thought is that I’ve always had my max altitude set as a crutch so that I wouldn’t accidentally bust the 400’ legal limit.  Maybe for safety reasons I should set that much higher and then just be diligent when flying to “manually” keep myself below the 400’ limit and leave headroom for the craft to go higher in an emergency if needed………setting max altitude to FORCE it below the legal limit seemed like a prudent thing to do, but now I’m not so sure about that………

2018-12-28
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ff22
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I want to see the "narrow escape" video!!!  But glad you and the craft survived.
2018-12-28
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Sato Zoom 2
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ff22 Posted at 12-28 12:41
I want to see the "narrow escape" video!!!  But glad you and the craft survived.

Well I hope this works, here's some screens.......it's the 5 seconds where I had no pulse LOL...


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2018-12-28
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DroPro
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Flight distance : 1134285 ft
Germany
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Good that the drone returned safely. Now that‘s a really good question and I‘m curious if DJI can answer that with factual input instead of „Thank you for reaching out ... blablabla“ Thanks for that question, I also wanna know.
2018-12-28
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fans8fe2d396
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Flight distance : 377464 ft
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I lost my drone, does anyone have any suggestions on how to find it?
2018-12-28
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DroPro
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Flight distance : 1134285 ft
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fans8fe2d396 Posted at 12-28 14:51
I lost my drone, does anyone have any suggestions on how to find it?

Sorry for that. Can’t you see the flight path in the DJI App on your phone? It should show you the last position just before you lost the connection.
2018-12-28
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fans8fe2d396
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DroPro Posted at 12-28 15:21
Sorry for that. Can’t you see the flight path in the DJI App on your phone? It should show you the last position just before you lost the connection.

Yes, I did.
2018-12-28
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ff22
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Sato Zoom 2 Posted at 12-28 13:19
Well I hope this works, here's some screens.......it's the 5 seconds where I had no pulse LOL...

Oh, sheesh, you were really close and really lucky.
2018-12-28
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ff22
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fans8fe2d396 Posted at 12-28 14:51
I lost my drone, does anyone have any suggestions on how to find it?

There is a "Find my Drone" function in the GO app.  Check the Manual on how to use it in addition to the tracking someone else mentioned.
2018-12-28
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