RTH and map malfunction resulting in crash

[Michael Ainsworth]

I believe that manually switching to Sport this disengaged the auto RTH being flown by the Drone.
That is you took over the programme.
I may be wrong someone else with more experience can tell you.
As an aside I posted in another thread about people using the radar on the screen, personally I use this more than the map as it shows me the real heading in relation to me.
This may have helped you in this case, although hindsight is a wondrous thing.
Sorry for your loss.

 

[geigy]

Whew - glad you are on Refresh!

I can see one or two things I think I would have done differently here, but in the heat of the moment in a new situation, there is not always enough time to figure out a new situation. I want to wait for one of our more experienced people to take a look and say what they think happened.

There's another person who went through a similar thing to yours, who lost his drone near the White Cliffs of Dover. He's quite an experienced pilot who did almost the same thing you did, came back manually because he wanted to avoid RTH taking on too much altitude, then overshot. He actually thought he had landed safely, but there was still another surprise waiting for him.

So it can happen to anyone. You just happened to be the unlucky one in a new situation, and it got out of hand. Thanks for sharing what happened - it may save other people from the same situation and maybe that will give you a little satisfaction! All the best.

 

[Marine0302G2/8]

My point was that if you had been looking at the video feed on your phone, you would have seen that you were over land and could have landed safely.

I could see on the screen that there was some green but that area has marsh and floating islands. So I thought that maybe I was at the water's edge. The distance away is what was messing me up. Because was scared that It would not make land and the fact that I lost visual I was unable to believe my lying eyes and common sense. lol

 

[YngveN]

I believe that manually switching to Sport this disengaged the auto RTH being flown by the Drone.
That is you took over the programme.
I may be wrong someone else with more experience can tell you.
As an aside I posted in another thread about people using the radar on the screen, personally I use this more than the map as it shows me the real heading in relation to me.
This may have helped you in this case, although hindsight is a wondrous thing.
Sorry for your loss.

I do believe you are correct that switching to sport mode will cancel the RTH. Also believe sport mode will drain the battery faster. And it was a few "high wind velocity" warnings that surely would mess with the Mavics heading.

 

[Marine0302G2/8]

Whew - glad you are on Refresh!

I can see one or two things I think I would have done differently here, but in the heat of the moment in a new situation, there is not always enough time to figure out a new situation. I want to wait for one of our more experienced people to take a look and say what they think happened.

There's another person who went through a similar thing to yours, who lost his drone near the White Cliffs of Dover. He's quite an experienced pilot who did almost the same thing you did, came back manually because he wanted to avoid RTH taking on too much altitude, then overshot. He actually thought he had landed safely, but there was still another surprise waiting for him.

So it can happen to anyone. You just happened to be the unlucky one in a new situation, and it got out of hand. Thanks for sharing what happened - it may save other people from the same situation and maybe that will give you a little satisfaction! All the best.

I wish I would have seen this video yesterday before my flight.

 

[Marine0302G2/8]

I believe that manually switching to Sport this disengaged the auto RTH being flown by the Drone.
That is you took over the programme.
I may be wrong someone else with more experience can tell you.
As an aside I posted in another thread about people using the radar on the screen, personally I use this more than the map as it shows me the real heading in relation to me.
This may have helped you in this case, although hindsight is a wondrous thing.
Sorry for your loss.

Thanks for the input. I feel like crap. Typically I always follow procedure. I should have just hit the return to home button. I was so far away and over water, I panicked. I did not think it would make back.

 

[YngveN]

Thanks for the input. I feel like crap. Typically I always follow procedure. I should have just hit the return to home button. I was so far away and over water, I panicked. I did not think it would make back.

In retrospect it is very easy to say you should have done so and so, in the heat of the moment I could easily have done the same.
However after seeing your case I hope I (and others) can learn from it and avoid similar situations.

I spent weeks reading about cases on this and other forums while waiting for my Mavic to arrive, and I can say for sure that have helped me to avoid a lot of problems.

Use your refresh and get that bird back in the air

 

[Rnl]

Glad it hit that pole looks like it was headed for road. Learn from this get your refreshed bird fly safe.

 

[Marine0302G2/8]

I watched so many videos and talk to multiple people about flying the Mavic and how to avoided common mistakes. I got too comfortable. When the reality hit me that I was so far away from the home point and over water I straight panicked. I should have just hit the RTH button and waited for it to come home. Thanks to everyone for the input. I hope this helps someone else from making the same mistake.

 

[pilotattitude]

At 12m 34s got a "low power returning home" That was the Mavic software saying hey I'm taking you home right now. So Mavic set its course. then I switched to sport mode and continued on the exact same heading that was established by mavic, with zero deviation. The Mavic should have flown right back to me. I was looking at the distance thinking it had not made land. Because the closest it ever got to the rth was roughly 278ft

From your story, it sounds like you overrode the automatic pilot. Which means you would have full operational control. Unless you reinitiated the RTH, the craft was performing under your manipulation of the controls. I also believe switching to sport mode will disengage the feature too. I'm still learning the full functions of my MP so I haven't left my property. But either way. DJI REFRESH and the fact you recovered your aircraft, does take the sting out a bit.

 

[Cyberpower678]

Set RTH at beginning of flight. Got a low battery warning return to home. I immediately switched to sport mode and flew the must direct route via the blue line on the map going to the home location. The Mavic past the home about 200 yards to the home point right flank. Came as close as 800 feet to home point but I could not tell its location because it should have flown right over my head but it did not. I stayed on the forward yoke to make sure I would not land in water. I feel like the Mavic for some reason tried to go to my home point that I normally fly from instead of the RTH that was set for this flight. I have the DJI care refresh agreement but I definitely want it replaced with a new Mavic. My poor baby is really busted up. My flight log shows that my home point is set and that the blue guide line on the map took the Mavic to the wrong place. Not sure how to download flight log to this thread.

I'm looking at your flight log now, but that video doesn't make me too happy. If that pole wasn't there, you would have hit that car. I'm not trying to be mean, just being honest. I do feel for you though.

 

[Cyberpower678]

Alright I finished my assessment. A lot of the people here already said what I want to say, so I will add on. I see you noticed that this was pilot error so I'm not going to depth commenting on why. No need to pile on and make you feel worse than you already do.

Here are the facts. RTH doesn't always work, and it actually may have failed if used on your return flight. You were flying in high winds of up to 33.7 km/h. The Mavic would have had to continuously fight and adjust for that using RTH, which could have burned through the power supply faster. So using Sport mode IMO was a good call. It too burns through power faster, but gives you much greater speed and distance. However, with those high winds, your Mavic was also drifting off course. The heading of the Mavic never changed but the horizontal path did. Now, while it was still reasonably on course, fighting the winds on the way back didn't make much sense, so letting it drift until it was over land would be better, and then guide the drone back to you once over land. This however takes us to not noticing the drone flying past you. When I played your video, while it was faint, I heard the drone fly by, so it definitely was noticeable. I'm assuming you were distracted by the nice young lady talking to you. Lastly, during a critical low power, the drone will start landing. If you really thought it was still over water, holding the throttle up all the way maintains altitude until the battery hits 0%, in which it then forces a landing. During an autolanding, the drone can still be steered, and you steered yours right into the pole, fortunately for you, and also unfortunately. That would have definitely ended badly if you missed the poll and hit a car instead.

So in conclusion, this was pilot error. Distracted flying is a killer. Always focus on the telemetry and video feed when returning on a low battery.

Good luck in future endeavors. Hope you get your replacement soon.

 

[Marine0302G2/8]

Let me start by saying this was absolutely avoidable. However after careful review of the flight log I have several question with regard to the auto landing mode, Return to Home feature & critically low power. Aircraft landing.

1. At 16m 3.6s auto landing mode engaged

2. At 16m 4.2s Critical low power. Aircraft landing message.

3. At 16m 4.4s Warning return home now

Question: It is telling me, “aircraft is landing”, why give the return home warning if it is going to auto land due to lack of power?

What is the difference between VPS altitude and IMU altitude?

4. At 16m16.4s the VPS altitude was at 0ft and the IMU was at 73.2 ft. and descending rapidly. At no time during the return flight did I adjust the altitude from its preset RTH of 162 ft.

Question: At the point in time that the Mavic has less than 10% power “Critical low power warning aircraft landing. I thought the Mavic would come to a hover until no power and land. Or attempt to return to the home point. Regardless of flying mode “sport”

My drone did not attempt to go to home point or drop to low / safe altitude and land or hover.

I assume sport mode manual control overrides any and all safety features?

In conclusion: Start with the longest leg of your flight on a fresh battery. If you get in trouble use the RTH feature and trust your Mavic to make home. Never switch to sport mode after you get a battery warning let the Mavic do its thing. I hope my misfortune will help someone avoid this unnecessary catastrophe in the future. Purchase refresh care.

 

[Cyberpower678]

Let me start by saying this was absolutely avoidable. However after careful review of the flight log I have several question with regard to the auto landing mode, Return to Home feature & critically low power. Aircraft landing.

1. At 16m 3.6s auto landing mode engaged

2. At 16m 4.2s Critical low power. Aircraft landing message.

3. At 16m 4.4s Warning return home now

Question: It is telling me, “aircraft is landing”, why give the return home warning if it is going to auto land due to lack of power?

What is the difference between VPS altitude and IMU altitude?

4. At 16m16.4s the VPS altitude was at 0ft and the IMU was at 73.2 ft. and descending rapidly. At no time during the return flight did I adjust the altitude from its preset RTH of 162 ft.

Question: At the point in time that the Mavic has less than 10% power “Critical low power warning aircraft landing. I thought the Mavic would come to a hover until no power and land. Or attempt to return to the home point. Regardless of flying mode “sport”

My drone did not attempt to go to home point or drop to low / safe altitude and land or hover.

I assume sport mode manual control overrides any and all safety features?

In conclusion: Start with the longest leg of your flight on a fresh battery. If you get in trouble use the RTH feature and trust your Mavic to make home. Never switch to sport mode after you get a battery warning let the Mavic do its thing. I hope my misfortune will help someone avoid this unnecessary catastrophe in the future. Purchase refresh care.

You didn't read my post above did you?

To answer your questions, it gave you a warning to return home. You can still steer your drone while it descends. It's trying to get you to bring the drone back. In your case you steered it into a pole.

VPS, Visual Positioning System, uses the visual sensors to gauge the height off the ground. It's only effective when 13m or lower. It uses that to maintain a stable however. Higher than that it uses the GPS, Glonass Position System, and the IMU, Inertial Measurement Unit, to track its height.

Sport or no sport mode, a drone can be maneuvered during descent. It doesn't just stop in mid air and land. Sport mode only deactivates Obstacle Avoidance. All other safety systems are still in operation.

"Never switch to sport mode after you get a battery warning let the Mavic do its thing."
Do not do that. Never rely on the autonomous features to do it for you. Many pilots, through pilot error, will lose the Mavic this way because they relied too much on the autonomy without properly setting it up. Your best chance was to always maintain control of the drone. Sure RTH is great, but it can fail, and pilot's need the skills to control the drone when failures occur.

 

[Marine0302G2/8]

Final question: How are you able to determine what the wind velocity was?

 

[Cyberpower678]

Final question: How are you able to determine what the wind velocity was?

I used Airdata and it is able to calculate wind at different points of the flight.

 

[Marine0302G2/8]

Thanks Cyberpower your insight is much appreciated

 

[YngveN]

You didn't read my post above did you?
Sure RTH is great, but it can fail, and pilot's need the skills to control the drone when failures occur.

Just out of curiosity, have you seen any cases where RTH failed? Sure Mavics have crashed during RTH, but in the cases I have seen this is due to RTH-height beeing set wrong or other user error.

 

[Marine0302G2/8]

No, I have not. I see cases where people don't understand exactly how rth is suppose to work and make pilot errors due to lack of proper understand. Myself included

 

[YngveN]

No, I have not. I see cases where people don't understand exactly how rth is suppose to work and make pilot errors due to lack of proper understand. Myself included

This is exactly what I have concluded with also. IMO RTH is extremely reliable if used correctly.

An other aspect I don't understand in this case, is why the Mavic continued full speed forward while auto landing.

The manual states:
The aircraft will land automatically if the current battery level can only support the aircraft long enough
to descend from its current altitude. The user can still use the remote controller to alter the aircraft’s
orientation during the landing process.

IMO this would mean that you can spin/turn the Mavic around while auto landing, but not move forward/backward/sideways.
In this case, did sport mode override this? Or was it due to the Mavic going into auto landing while full forward was was applied?