How I Lost My Mavic 2 Zoom

[hermitdog]

One week ago today, on October 13th, I flew into this gulch called "Buzzard's Roost." A friend took this photo of the ravine with his drone - but he was smarter than I and did not attempt to fly as far into the gulch as I did. I have added text and arrows to his photo to explain what happened.

 

[UAVNV]

It happens, appreciate the fact that you took the time to understand the point of failure in your flight.

do you plan to continue flying?

 

[hermitdog]

I ABSOLUTELY plan to continue flying! I sold all of my Mavic 2 Zoom cables, controller, charger, batteries, etc, on eBay, and the very next day I bought a new Mavic Pro -- I'll miss the Mavic 2, but people are saying GREAT things about the Mavic Pro, so I'm looking forward to flying it. Sadder but wiser, as they say.

 

[Rusty in Bend]

Ouch. That's painful to read. I see so many "tree crashes" ... that I've tended to stay either well above, or away from forests. And I never take off from a location that isn't clear enough to allow for an easy RTH and/or visual landing. Stories like this reinforce my "Crashadroneaphobia".

 

[Kilrah]

You shouldn't be afraid of trees, buildings and hills work "just as well" to eat drones as per many threads here. Just understand to set your RTH height above the relative height of any obstacle you're going to go behind (or don't go behind stuff in the first place based on the understanding that RF has a hard time going through obstacles so loss of link is likely).
And land at 25-30% battery instead of pushing it unreasonably.

 

[hermitdog]

Excellent responses and advice. My home is surrounded by tall trees, but I've never had a problem with RTH set at 200 feet. (I ALWAYS land manually once the AC has descended to just above tree height, anyway.) But my error with this ill-fated flight was not really about trees; it was forgetting that flight altitude is measured from the launch location. Thus, "maximum altitude reached" was not really 400 feet after I'd flown up and into the gulch. However, because the drone thought it was at maximum altitude, it was impossible to ascend any further. I still could have flown back around the obstructing ridge - IF I'd have had a signal connection, which I'd lost. Now -- if I'd have flown into the gulch from the top, instead of the bottom, of its hills, I'm pretty confident that I'd still have my Mavic 2. Returning home at 25% battery would probably also have prevented the loss.

re "Crashadronaphobia" -- Get back on the horse that threw ya!

 

[daveatpdx]

Is there any way to reach the crash zone? I crashed my Mavic in an inaccessible, overgrown valley. I thought that it would not be worth retrieving. But I really wanted the chip because I thought I had some good images. So I took a rope and walking poles and spent a couple hours fighting the brush and lowering myself down steep declines, found it, brought it home, replaced two props, and it flew and photographed perfectly. They are tough little beasts.

 

[hermitdog]

Thanks for your concern. I'm 76 years old, and I'm sure it would not be possible or safe for me to hike to the "soft landing" site. My 34-year-old flying companion (who took the photo in this thread) also felt it impossible to hike through the cliffs, dense forest, and across the creek to find the drone. I learned an important lesson from this error and hope others will learn it too: Do not fly toward a steep incline, let your drone go out of sight, then fly behind an obstacle (in my case a large ridge) that blocks the RC signal. Once I made all of those errors, I could not ascend (because the drone thought I had reached maximum altitude) and I could not steer (because the drone could not receive a signal from the RC.) Note: the drone performed perfectly. Once it lost the signal, it began the RTH, flew 900 feet back, then got trapped behind the large ridge that you can see in the photo. Thanks again, Dave, for your concern.

 

[daveatpdx]

I had a similar crash where my key error was flying behind a hill. Like you I could not get the drone to climb high enough (still don't understand why; it was below the take off point but still would not climb). I did not have enough experience at that time to know where the drone was without seeing it. I tried to escape to the side but by then the battery was too low. It crashed in dirt. I found it the next day and put in a new battery and it worked fine.
Glad that a fellow oldster is enjoying this stuff too. (I"m 73).
Dave

 

[hermitdog]

Maybe the hill blocked your controller's signal. . . ? I don't know; just guessing.
Happy to hear your adventure had a happy ending, though.

 

[Kingdave]

Could you have changed your maximum flight altitutde during your flight when you seen it was stuck? Or did you not have time?

 

[Meta4]

Maybe the hill blocked your controller's signal. . . ? I don't know; just guessing.

Maybe??
If you fly behind a mountain, a tall building, a forest etc, you will lose signal.
Don't fly behind obstacles.
You need to have a clear, unobstructed line of sight to have control of your drone.

 

[hermitdog]

I'm pretty new to drone flying, but I thought 400 feet was the maximum altitude anywhere in America. Since the drone measured its altitude from the home point, as soon as I'd ascended 400 feet above that point, I could go no higher. Problem was that the hills were higher (!)

You have it right, Meta4. No wonder the FAA says to keep a line of sight at all times. (Does anyone actually DO that?) - I mean, with a drone the size of the Mavic, it becomes invisible beyond 500 feet or so. . . and folks claim to have flown it several miles.

 

[Meta4]

You have it right, Meta4. No wonder the FAA says to keep a line of sight at all times. (Does anyone actually DO that?) - I mean, with a drone the size of the Mavic, it becomes invisible beyond 500 feet or so. . . and folks claim to have flown it several miles.

People get confused by the expression Line of Sight.
The FAA talks about VLOS (Visual Line of Sight) meaning keep your drone in visual range
LOS is a different kind of law.
It's a law of physics that radio signals won't travel through mountains.
Your drone could be 10 miles out and still be in LOS but it might be out of VLOS at 900 ft.

 

[DanMan32]

Low frequencies may get around some obstacles, even through them. Higher frequencies in the Ghz are very susceptible to attenuation through objects, even leaves.

 

[Ian in London]

One week ago today, on October 13th, I flew into this gulch called "Buzzard's Roost." A friend took this photo of the ravine with his drone - but he was smarter than I and did not attempt to fly as far into the gulch as I did. I have added text and arrows to his photo to explain what happened.
View attachment 50875

Well, I totally share your pain, having lost mine over the White Cliffs of Dover almost 2 years ago. But you analysed the flight, worked out what went wrong, and crucially went out and bought a new one straight away. Just as I did, and as you say, it's a tough but good lesson.

The general advice above is spot on; the moment you fly around large objects, you run the risk of signal loss and a bee-line back to take off point. In addition, flying around trees very often impacts signal strength and you will be more prone to signal loss. My advice is always stay away from trees, buildings and people....

Have fun with the Pro

Cheers
Ian in London

 

[hermitdog]

Thanks for taking the time to share your pain, Wellsi. Unfortunately, I could not afford to replace my Mavic 2 Zoom with another one, so I got a brand new Mavic Pro at almost half price. It's a great little machine - but without the obstacle avoidance sensors of the Mavic 2. I'm also looking into the "Terrain Follow" flight mode and wondering if it would "rise to the occasion" (maintain the same altitude above ground) if I were flying the drone uphill but not following anything.

btw, I would LOVE to be able to fly my drone over the white cliffs of Dover!

 

[DanMan32]

Thinking about it, and you mentioning terrain follow, RTH and obstacle avoidance should have prevented a crash, unless AC reached its altitude limit, or obstacle was enough where avoidance couldn't figure a way out, so it hovered until battery died.

 

[Jack Daw]

On the MA, at least, an RTH initiated when the controller loses signal doesn't make a 'beeline' back to its point of origin: it follows the path it took to get there, no matter how curved or erratic it may have been. Is this not true of the MP2?

 

[Meta4]

On the MA, at least, an RTH initiated when the controller loses signal doesn't make a 'beeline' back to its point of origin: it follows the path it took to get there, no matter how curved or erratic it may have been. Is this not true of the MP2?

Not quite.
The drone will only reverse it's course to the point it regains signal or for 60 seconds, whichever happens first.
If signal is not regained, it's the straight line home .

Here's the relevant section from the MA manual:
When Failsafe RTH is activated the aircraft starts to retrace its original flight route home.
If the wireless control signal is re-established within 60 seconds of Failsafe RTH being activated, the aircraft hovers at its present location for 10 seconds and waits for pilot commands.
The user may tap X in the DJI GO 4 app or press the RTH button on the remote controller to cancel Failsafe RTH and retake control.
If no pilot command is given the aircraft flies to the Home Point in a straight line.
If the wireless control signal is still lost 60 seconds after Failsafe RTH was activated the aircraft stops retracing its original flight route and flies to Home Point in a straight line.