Mavic did not RTH. Kept drifting away and had to do an emergency landing. Why?

[pseudeep]

Hi experts,

First off, I am relatively new to droning and just received my Mavic five days ago. I had been reading up in prep for it and have run a bunch of simulations and short practice flights after receiving it. All have been successful with no crashes.

Yesterday, I took it out for a flight in a relatively open area (large area that has construction going on in some spots, but large open swaths of land in others).I mainly wanted to test the RTH function and fly a little further (LOS) than usual. Below is my healthydrones summary:

HealthyDrones.com - Innovative flight data analysis that matters

If you look at the Notifications tab, you can see that 1 minute 9 sec into the flight I initiated RTH (when the drone was 188 ft away). It successfully returned to home. If you see, I have set my RTH altitude the same as Max altitude (400 ft), so it gave a "max altitude reached" warning when RTH. I will be changing that so that my RTH altitude is lower than the max altitude. Anyway, it returned to home.

At 4min 8 sec, it reached the home point and was hovering 4ft about the home spot. At that point, I canceled RTH and flew it back up into the air (since I gained confidence by this point that the RTH function was working fine). This time, I flew it further out but still within LOS, for the most part. As you can see, at 8min 27 sec, it was at the farther end of LOS for me and I decided to initiate RTH again.

This is when things started getting out of hand. Although it started beeping stating RTH was initiated and it was climbing up to RTH altitude, I thought at some point it would start flying back to home. But it kept drifting away with the wind. At 9 min 2 sec, it reached max RTH altitude, but stayed at that altitude and kept drifting away for a good minute. At 10 min 2 sec, I got really worried after a minute of drifting away in RTH. So I canceled RTH and tried to maneuver the drone back myself. I tried to point the drone back in the direction facing home (using the arrow on the GPS map on the DJI Go 4 app). After pointing it back home, I kept pushing the forward direction control for a while, but it seemed like the drone kept drifting away and the forward command did not seem to work. Finally I turned the gimbal vertically down and after drifting over some water, I was able to bring the drone down. Fortunately the descend control seemed to work and I was able to land it in an open construction lot with minimal damage to key components.

My question is: why did the RTH function not work in this case? It seemed like a moderately windy day (15-20 MPH winds). I seemed to have full GPS strength. Did I do something wrong, or is there a setting change that I need to make, which might have caused the drone to drift away during RTH? It was also quite a cloudy day...the sun was not visible and I was not flying into it (this was around 11am). Also, I had prop guards mounted on the drone.

Please let me know (hopefully politely) if this was user error or not, so I can learn, keeping in mind that you might have been beginners too at some point in your journey. Could the prop guards have caused the drift due to additional drag on the drone...or should I have not been operating the drone in winds of this speed? If the wind speed caused the issue, why did it RTH the first time? Thanks.

FYI - I have the leg extensions installed on the drone as well.

 

[BD0G]

As you have already surmised you have the RTH altitude set WAY too high.

While wind speeds at the ground location may have been 15-20 MPH
Winds at higher elevations can and usually are much stronger so that can cause drift even if holding the right stick full forward. While in P Mode flying the Mavics top speed and forward pitch is limited. This will not allow it to cheese wedge itself through strong winds and high altitudes.

In order to fight those high winds one should reduce altitude to a safe height over obstacles , but not up at 400 feet AGL .

Then use the switch on the right side of the remote controller and switch it up and into SPORT MODE. Now you are cooking with gas. Higher speed is obtainable and forward pitch is allowed to become much more aggressive and the Mavic will carve forward through the wind.

You could also do this. Let her drift away without forward stick movement , but instead drop altitude. Then Sport Mode after lower altitude has been achieved and then slice back though the lesser wind resistance.

When going full stick in P Mode into wind you are just treading water (or air in this case) and wasting precious battery power achieving nothing.

Dropping out of the air takes much less "juice" as the Mavic is just fighting the wind to remain upright and horizontally balanced.
Also - Ditch the prop guards for outdoor flying as they act as wind socks and inhibit your Mavic even more.

 

[BD0G]

Another thing to note with such a high RTH setting is say you flew above 16 meters right in front of yourself and then pressed and HELD the RTH button. Well you would waste a shite ton of battery as the Mavic would then ascend to its preset RTH altitude -in your case 400 feet AGL. Then come straight back down to its Home point. Talk about wasteful and with high winds risky business.

My RTH is usually max of 120-140 feet AGL. That will clear most obstructions in the areas I fly commonly.

 

[Strafe1]

As you have already surmised you have the RTH altitude set WAY too high.

While wind speeds at the ground location may have been 15-20 MPH
Winds at higher elevations can and usually are much stronger so that can cause drift even if holding the right stick full forward. While in P Mode flying the Mavics top speed and forward pitch is limited. This will not allow it to cheese wedge itself through strong winds and high altitudes.

In order to fight those high winds one should reduce altitude to a safe height over obstacles , but not up at 400 feet AGL .

Then use the switch on the right side of the remote controller and switch it up and into SPORT MODE. Now you are cooking with gas. Higher speed is obtainable and forward pitch is allowed to become much more aggressive and the Mavic will carve forward through the wind.

You could also do this. Let her drift away without forward stick movement , but instead drop altitude. Then Sport Mode after lower altitude has been achieved and then slice back though the lesser wind resistance.

When going full stick in P Mode into wind you are just treading water (or air in this case) and wasting precious battery power achieving nothing.

Dropping out of the air takes much less "juice" as the Mavic is just fighting the wind to remain upright and horizontally balanced.
Also - Ditch the prop guards for outdoor flying as they act as wind socks and inhibit your Mavic even more.

Perfect explanation here.

 

[BD0G]

Perfect explanation here.

 

[pseudeep]

Thanks BD0G. I agree about the RTH altitude. That was just me trying to be overcautious. I now realize that 120-150 ft. RTH altitude should be more than enough for me to return back safely as well.

I will probably take the prop guards off soon if they seem to be causing drag (or try to limit my flying to low wind days for the next few times until I am more comfortable). I like the Sport Mode suggestion in these type of emergencies. I hadn't tried that yet based on where I currently am in my learning curve, but a good thing to know and practice, just in case.

I just wanted to make sure I was not missing any type of setting or having any issues with my Mavic. I really the appreciate the help that you have provided and will hope to pay it back or forward some day! ;-)

 

[BD0G]

Sport Mode is essential! I jet out to chosen filming location on full boost. Then drop into P Mode or Tripod (other intelligent flight modes) . Capture footage . Then switch right back into Sport Mode for the ride back. Lots of pilots use this methodology.

Take your prop guard money and instead buy a $60 dollar a year personal articles policy for your Mavic only. You do not need to be currently insured with StateFarm to have them issue this policy. It covers everything that could potentially happen to your Mavic and will allow you piece of mind to fly with more confidence.

 

[pseudeep]

Wow. Learnt something new today about the personal articles policy for the drone! Wish I had known this before plunking down money for the DJI Care Refresh (even though I have heard all kinds of s**t about DJI customer service).

Thanks BD0G. You rock! Now I'm wondering if I should contact State Farm right now or whether I should wait the 1 year until the DJI Care Refresh is close to expiring before contacting State Farm. Decisions decisions!

 

[Birdman5280]

Don't wait on getting covered by State Farm. I've got both SF and DJI refresh. Several members here do. It's worth every cent.

 

[Randy]

Another thing to note with such a high RTH setting is say you flew above 16 meters right in front of yourself and then pressed and HELD the RTH button. Well you would waste a shite ton of battery as the Mavic would then ascend to its preset RTH altitude -in your case 400 feet AGL. Then come straight back down to its Home point. Talk about wasteful and with high winds risky business.

My RTH is usually max of 120-140 feet AGL. That will clear most obstructions in the areas I fly commonly.

I lost GPS once also when it was windy, it immediately started to drift away, and I tried to bring it back in ATTI mode (which it had gone to when it lost GPS) I did not have enough power authority to overcome the wind and bring it back until I switched to sport mode, it was like night and day.

 

[pseudeep]

Thanks all. Again appreciate the tremendous help.

Birdman5280, is there any benefit to having the DJI Care Refresh in addition to the State Farm policy? Just curious.

 

[zebrock]

I

Thanks all. Again appreciate the tremendous help.

Birdman5280, is there any benefit to having the DJI Care Refresh in addition to the State Farm policy? Just curious.

If you lose your MP, or its stolen, Refresh does nothing for you. SF on the other hand, will cover it.

 

[BD0G]

Thats correct. DJI wants the Mavic sent in to them to have it covered under the refresh care option. If you dont physically have the Mavic Pro (due to theft , dropped in the lake or ocean, flew away and cannot be found, etc) then you will be unable to use the refresh option.

Sounds "Refreshing" right?

 

[pseudeep]

Sorry, I should have stated my question in a better way. It sounds like the SF policy is better than the DJI care refresh. I guess I was wondering if there is any benefit to having the DJI care refresh at all then? Is there any situation that is covered by DJI care refresh but not by SF? As stated earlier, had I known this before my purchase, I probably would not have bought the DJI coverage at all? I'm now desperately trying to find something that will make me not regret plunking down the $99 for the DJI coverage

Well at least I am better informed now and can warn anyone else that I know who might be looking to buy a DJI or an expensive drone.

 

[pseudeep]

Also, in reference to my original post about the Mavic drifting away due to high winds - I did run the simulator in the DJI app last night to mimic the relatively high wind conditions. At high enough winds (like 10 m/s or 22 mph in the simulator), the simulator itself shows the drone drifting away due to such high winds (unless in sport mode). At wind speeds higher than that, even sport mode doesn't seem to work.

Lesson learnt and reason confirmed! I'm going to watch wind conditions like a hawk from now on, before flying the Mavic

In a related note to the prop guards, there seems to be a Mavic setting in the app called "Enclosed Propeller Guard". It's an ON/OFF toggle switch. Anyone know what it does?

 

[BD0G]

Turning Prop Cage on and off allows the Mavic to attempt to compensate for the additional drag and influence that they (the prop guards) would have upon flight.

Refresh does not cover anything that StateFarm Personal Articles Policy would not already cover.


Watching wind conditions at ground level can only go so far as they can be much higher up above.

 

[pseudeep]

"Refresh does not cover anything that StateFarm Personal Articles Policy would not already cover." ...thanks for bursting my bubble. haha

I'm hoping to use the Windytv, wind forecast app to get an idea of wind speeds at higher altitudes. The website gives wind speeds at 100M altitude, so that should at least serve as a good gauge. Thanks for all your help!

 

[CyberNate]

In addition to all these great responses, there is also the option of pushing the right stick (pitch) full forward while in Return to Home mode. The airspeed will increase from 20mph to over 30mph. If that is not enough, then you'll have to switch to sport mode to get full power. As others have stated, bring the craft to a lower altitude will also help.

 

[BD0G]

"Refresh does not cover anything that StateFarm Personal Articles Policy would not already cover." ...thanks for bursting my bubble. haha

I'm hoping to use the Windytv, wind forecast app to get an idea of wind speeds at higher altitudes. The website gives wind speeds at 100M altitude, so that should at least serve as a good gauge. Thanks for all your help!

I just call em as I see em.
Statefarm is really great to have as it takes alot of the stress of crashing or not being able to find ones Mavic off the table.

 

[pseudeep]

In addition to all these great responses, there is also the option of pushing the right stick (pitch) full forward while in Return to Home mode. The airspeed will increase from 20mph to over 30mph. If that is not enough, then you'll have to switch to sport mode to get full power. As others have stated, bring the craft to a lower altitude will also help.

Thanks CyberNate. I did not know there was the option to control/increase the forward speed in RTH mode. Will keep that in mind going forward. I basically haven't flown again since this event a few days ago, but after all these discussions, I've built up my confidence again and can't wait until the next low wind day to take it out again.