Nearly lost my Mavic Air this morning - Home Point changed randomly

[Bondaneka]

Sorry, I have tried to locate the DAT file on my mobile phone to no avail. The flight took place two days ago on 26 March but for some inexplicable reason - and assuming that I am interpreting the file naming convention correctly -there appear to be no DAT records for that date (see screenshot below).

 

[netfolks2000]

Just finished reading through this and wanted to say thank you to all of the experts out here who are willing to jump in and help another drone pilot when things go awry. My first drone is the Mavic Air so I’ve only had it less than 2 months but have learned a ton from this forum. Flight pre-checks, actually reading the manual and understanding all that the drone can do, and above all, actually praciticing in safe areas - not just flying wherever I want. I feel like I’ve learned a ton in the past 2 months and hope to never have to post on this forum that I lost my Air. I still have lots to learn so I’ll keep soaking it up. Thank you!

I'm reading this like a fantastic mystery drama, not to the end yet, but I also would like to say THANK YOU for you guys who step in to solve these mysteries. You are appreciated.. Now back to the story....

 

[netfolks2000]

I don't mean to change the direction of this thread but this is related. I hope this one question is related to this problem. Yesterday when flying low in another pasture I lost my link to the drone. I had to restart my phone and the controller to regain contact with the drone. Fortunately I could hear that RTH started and it was coming back in my direction. So here is the question: Should we use the option HOVER IN PLACE when contact is lost as a default or continue to do failsafe RTH? Which is recommended? In this case with Bondaneka, would it have been better for his drone to just hover while he tried to get close to it to regain control?
(When I lost control I was very low to the ground, about 12 feet, trying to herd some cows.)

 

[joejaxvic123]

My issue with hover in place would be the risk of not being able to reconnect, battery goes dead, bird force lands in an undesirable location.

 

[sar104]

I don't mean to change the direction of this thread but this is related. I hope this one question is related to this problem. Yesterday when flying low in another pasture I lost my link to the drone. I had to restart my phone and the controller to regain contact with the drone. Fortunately I could hear that RTH started and it was coming back in my direction. So here is the question: Should we use the option HOVER IN PLACE when contact is lost as a default or continue to do failsafe RTH? Which is recommended? In this case with Bondaneka, would it have been better for his drone to just hover while he tried to get close to it to regain control?
(When I lost control I was very low to the ground, about 12 feet, trying to herd some cows.)

If you are flying under obstructions, trees, etc then RTH hover may be a better option. Generally not though.

 

[chazzm]

This is curious because I’ve noticed discrepancies on my Mavic Pro and RTH coordinates changing randomly at times while in flight! My bird would record the home point but was actually two points BEHIND!! I only noticed this when my battery went low and RTH activated,,, I expected it to come land at take off point but it bypassed me and went to the second home point back!! After updating to the latest FW this problem went away! I have to wonder if DJI inadvertently screwed up kept quite about it and fixed the problem on the sly?? Because this should not happen!

 

[joejaxvic123]

chazzm: Did you move and update your home point while flying? Just curious because mine overshot without me updating HP.

 

[Gizmo]

Bondaneka you seriously need to read the manual before flying, I noticed it at first when you said you were expecting your aircraft to descend after the RTH, the mavic will either only ascend or keep current altitude, depending on your RTH settings, but will only descend when landing at the home point. Knowing that by pressing the pause button or enabling sport mode will cancel RTH could have saved you lots of trouble.

I don't mean to be rude, but reading the manual and having a good preflight checklist are the most basic things to ensure that you have a fun and safe flight.

 

[Bondaneka]

Fair point Gizmo - lesson learned and I have done as you suggest

 

[BJR981S]

This has been a serious issue since DJI introduced the "current location" as a RTH point. There is a zillion checks and warnings from the Drone on the number of sats and the HDOP accuracy of the Home lock but nothing checks the Phone GPS. It is all too easy for the phone location to jump around and there is no way to check or warn about its accuracy. Also flying near a magnetic anomaly will cause the heading reported to drift often pointing the wrong way for a RTH.

My advice. (my Two Bobs Worth) I do not use RTH. I bought my drones to fly, not watch them fly. RTH, I treat as an emergency measure that I hope I will never have to use. Like if I drop my controller and Smart-device in the river.

I have only ever had 1 RTH since I started flying drones and that was my Phantom 2 Vision Plus years ago. That for some reason lost the Transmitter signal.

And using Auto RTH so you can extend the flight times out of your model is just plain dumb. Depleting batteries well below 50% just shortens their life and reduces the number of cycles you can effectively charge the LiPos.

Cheers

 

[Aerial West]

If it means anything, i never let my students use RTH. I personally have never activated RTH on any drone.

There's a few reasons for that, beyond this threads example. I really feel like more stick time flying and understanding your drone and orientation is valuable experience. landing manually is a skill necessary if automatic fails, and accordingly you should be very familiar with it.. far more familiar that an automated process. And every minute you have on your drone maneuvering, including landing, makes you a better pilot.

In a sense, RTH is like always flying in GPS mode, rather than learning ATTI mode and how to fly in it if GPS fails. You should know how to fly your drone in the most manual, least automated settings so that you are always prepared.

It sounds like this guys phone may have had some GPS drift. I am not surprised. Being able to deactivate all automated features and immediately and competently fly your drone is critical.

 

[cab124]

Do the experts who have been studying this case see any correlation between problems like this and Android vs. iOS devices? I like both types of phones, but I have tended to notice that when I read through threads such as this, they seem to be skewed toward people who are using Android devices. Am I off base on this?

 

[Aerial West]

Do the experts who have been studying this case see any correlation between problems like this and Android vs. iOS devices? I like both types of phones, but I have tended to notice that when I read through threads such as this, they seem to be skewed toward people who are using Android devices. Am I off base on this?

I'm a huge fan of Android, but dji does a much better job with the Apple app.

 

[sar104]

Do the experts who have been studying this case see any correlation between problems like this and Android vs. iOS devices? I like both types of phones, but I have tended to notice that when I read through threads such as this, they seem to be skewed toward people who are using Android devices. Am I off base on this?

There were some problems with Android devices under earlier firmware, but those have been fixed. It's not clear to me, even in this particular case, whether the phone's location data were bad or whether the Go app was not interpreting them correctly. Either way I agree - these problems seem to be reported far more often on Android.

 

[BJR981S]

You actually need to see what the specification is for the GPS capability of the Smart Device.

Smartphones and tablets in the Android world have a huge range of GPS capability from little to enhanced.

The important specifications:

Is it GPS, or GPS / GLONASS (Dual GPS)

How many RX channels. The more the better.

I use both Android and IOS. But the Androids are DJI Crystal Sky Displays with enhanced GPS capability.

This is basic HW outside of any FW and IOS / Android related bugs.

 

[Travisimo]

If it means anything, i never let my students use RTH. I personally have never activated RTH on any drone.

While I agree in principal, it's also somewhat difficult to avoid using RTH at least occasionally on an aircraft that uses WiFI as its transmission technology. Even if you confine yourself as a pilot to flying within line of sight, there is definitely the potential to lose transmission in congested locations. So unless you're willing as a pilot to limit yourself considerably in location and distance, you may very well encounter the need for Failsafe RTH. Therefore, I also think it's imperative to teach RTH while simultaneously training pilots not to make it part of regular flights.

A low-battery RTH is easier to avoid than a Failsafe RTH, as you can still take control and fly the aircraft yourself with the former (especially if you are within LOS). With Failsafe RTH, you have no control and thus have no choice but to rely on this important safeguard. WiFi is so variable that even with good practices you may encounter a disconnect.

 

[Lake_Flyer]

there is definitely the potential to lose transmission in congested locations

Exactly, that's why one shouldn't fly in a congested area.

 

[Simmo]

I'm a huge fan of Android, but dji does a much better job with the Apple app.

Weird eh. when the aircraft runs on an Android OS!

 

[BJR981S]

that uses WiFI as its transmission technology

Mavic Pro does not use WiFi. It uses Occusync. It just so happens that it uses the 2.4Ghz band. Just like new 2.4Ghz RC transmitters that also are not WiFi.

This is the technology that gives the Mavic its 7 km range. Phantom 4 Pro uses Lightbridge 2 also in this same spectrum to give 7 klm rang. It also is not WiFi.

Cheers

 

[sar104]

Mavic Pro does not use WiFi. It uses Occusync. It just so happens that it uses the 2.4Ghz band. Just like new 2.4Ghz RC transmitters that also are not WiFi.

This is the technology that gives the Mavic its 7 km range. Phantom 4 Pro uses Lightbridge 2 also in this same spectrum to give 7 klm rang. It also is not WiFi.

Cheers

That's an important distinction that makes a big difference, but this discussion was about a Mavic Air, which does use wifi.