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Saved by Mavic's Forward-Looking Sensors

Conservative Nihilist

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Nov 9, 2020
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Age
39
Location
Down the dirt road a ways.
For the first time ever, I saw the benefit of having a forward-looking collision sensor-equipped drone. Most of the time I fly my trusty Phantom 3S, launching it on autonomous flights far beyond signal range because it is perfectly legal to do so in my remote Third World location. My drone's usual altitude in this area has always been 150 feet AGL, and I'd never had any issues at that height.

A new airport is being carved out of the jungle a few miles away, and I decided to check it out flying my Mavic Pro, without the benefit of a Litchi flight plan, because I wasn't sure about the exact location of the runway that is being bulldozed. Drove to a secure location about a mile from the site, and flew over the area at 200 feet AGL, returning to base without incident.

With my confidence thus boosted, and the location pinpointed on my Litchi map, I decided to prepare a flight plan that departed from a different location that was about 20 feet lower in elevation than the original launch site. Sent the Mavic on its way, at a lower altitude of 150 feet AGL so as to have a better look at the proposed airport, and soon the bird was out of signal range, presumably flying the waypoint course without a hitch. Twiddling my thumbs I awaited its arrival.

About 22 minutes later, the drone arrived after auto-RTH evidently kicked in, which I found a bit odd, since I'd flown the Mavic on flights of identical duration before, without having RTH taking over. When I reviewed the footage, however, my jaw dropped, because the drone had just barely cleared several treetops, and was clearly NOT flying at 150 feet AGL as programmed. The altitude was more like about 80 feet AGL, which was just a hair above the palm trees.

Finally, as the footage played, the Mavic was on a direct collision course with a tall palm tree right beside the newly bulldozed runway, but then, to my grateful amazement, it slammed on the brakes at the very last instant, swiveled around, and made a beeline for home. That entire sequence of events took place well beyond signal range, and I was none the wiser until I played the footage back.

The purpose of this long dissertation is to recount a new lesson I have learned just today about programming Litchi flights, which is that if the launch site is lower in elevation than the course to be flown, a very generous margin of error must be applied to the altitude, so as to avoid hitting trees or terrain.

I have flown my Phantom3S close to 2,000 miles cumulatively, and never experienced any near misses with trees, yet, I am now absolutely certain that the Phantom would have hit that palm tree and joined its ancestors right there, if I had flown the Phantom and not the Mavic today. Thank goodness for Mavic's obstacle avoidance technology. Here are a few screenshots of the near calamity that taught me this vital lesson about staying at a safe height.

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If that was me and it had hit that tree and never returned I would run around like a headless chicken until I found it or died of exhaustion or starvation.
I'd have been inclined to try looking for it if it hadn't returned but the place is under military guard around the clock. That said it isn't fenced off yet, so I'd have been tempted to pose as a butterfly collector who got lost if I got caught snooping around haha.
 
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Climbing a tree would solve all your problems, unless you got shot… In which case… I never suggested that, and I was never here.
 
Haha getting shot would be a possibility for sure if I forgot to bring along some loose change to oil the wheels of progress, as it were. An adventurous buddy of mine bluffed his way past the sentries a couple of times by claiming he owned a farm in the general area, but he did offer up a generous donation towards the day's beer fund on each occasion.
 
And the mini graced us without this technology forward facing. Maybe to reduce weight, maybe some other reason; don't know. But it is useful, when the camera isn't even looking forward for one.
 
I see the third pic. I assume that's where your drone stopped and turned around? You're very lucky.

That was indeed the very moment when the drone stopped, paused, spun around, and headed home. Watching the footage, and having entirely forgotten about the forward-looking sensors on the Maic Pro, I was expecting to see the drone miraculously slip between the swaying palm fronds, but when it stopped, I finally realized what had happened, and my hat is off to DJI engineers for this marvel of drone self-preservation.

This incident also illustrated the sequence of steps that will unfold if obstacle avoidance occurs during a fully autonomous flight. The drone will not rise above the obstacle and resume the waypoint mission, but will rather call it a day, and head straight home. This was poetry in motion to behold. When it comes to drone technology, the Chinese are the absolute masters of the genre.
 
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This is one time where video would have been nice. Once that Air Port is in , things are going to change quickly .

Phantomrain.org
Gear to fly your Mavic Pro in the Rain and the Jungle.
Now that I have an even more precise fix on the location of the future terminal building complex, I've programmed a 22-minute double loop over that area in Litchi, and will take another recon flight at 200 feet AGL to produce some footage I can post on youtube and share here.

Until the location is registered with the ICAO and added to the global NFZ list by DJI, I'll be snooping around satisfying my curiosity, thanks to the Mavic Pro. Decided not to send the Phantom3S due to the racket it makes, and the ease with which it could fall victim to a well-placed shotgun blast. No sense in pushing my luck.
 
That sounds… Less than legal on the side of the officials.

That is a tactful way of describing the situation here. Over the years out here in the sticks, I've lost count of the number of times I've been gently relieved of spare change at police checkpoints dotted along the pot-hole-riddled roads.

The main difference between such unofficial "toll collection points" and a regular stick-up is that the rifle muzzles generally stay pointed in a safe direction, and gratitude is expressed for my kind contributions to the smiling officers' welfare fund. I understand a similar protocol is observed in Russia, with the difference being that a crisp salute is offered to motorists that are prompt and generous in their response to donation requests.
 
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