DJI Mavic, Air and Mini Drones
Friendly, Helpful & Knowledgeable Community
Join Us Now

Almost lost my Drone

Where did he break 400ft AGL?
I don't have google earth and the terrain map I have isn't very good so I can't judge his AGL but, relative to the launch point, the max height I can find is 395ft.
The IMU altitude only reports the height above the launch point. When the aircraft landed, its final position was -17'. It didn't burrow a hole in the ground. The ground was lower than the launch point.

Look at 17m 37.9s on the log. The IMU reports altitude of 2 feet. Sure, it could be off by some. But the VPS, which is more accurate, has the altitude at nearly 32 feet.

This is the reason the IMU cannot be relied on, and the reason you need to maintain VLOS. At that point the variance is 30 feet! When the drone was at its highest, 391 or whatever, according to the IMU, there is every possibility it was in fact over 400', since it passed over a point earlier where the variance was 30 feet.
 
Actually it wasn't.
He flew over rising ground that rose approximately 150 feet higher that the launch point.

The landing spot was about 30 ft lower than the launch point, but it's common for the indicated height to drift +/- 20 ft or so over the duration of a flight anyway.
Yeah, no. The VPS altitude shortly before landing was positive, as you would expect since the drone is in the air. The IMU reports below its original launch point. You're right in that there is a variance of around 30 feet. THE OTHER WAY. The actual aircraft height is 30 feet ABOVE the IMU reported altitude on at least one occasion, look at 17m 37.9s.
 
Yeah, no. The VPS altitude shortly before landing was positive, as you would expect since the drone is in the air. The IMU reports below its original launch point. You're right in that there is a variance of around 30 feet. THE OTHER WAY. The actual aircraft height is 30 feet ABOVE the IMU reported altitude on at least one occasion, look at 17m 37.9s.
At 17:37.9 the drone is landing over a point that is 30 feet lower than the launch point.
With the IMU indicating it is only 2 ft higher than the launch point, the VPS is showing 31 .5 ft.
In this case the IMU altitude doesn't appear to have drifted during the flight and is giving an accurate height relative to the launch point.
 
  • Like
Reactions: rjwmorrell
At 17:37.9 the drone is landing over a point that is 30 feet lower than the launch point.
With the IMU indicating it is only 2 ft higher than the launch point, the VPS is showing 31 .5 ft.
In this case the IMU altitude doesn't appear to have drifted during the flight and is giving an accurate height relative to the launch point.
I agree, the IMU probably hasn't "drifted". You just repeated my conclusion. Now add that same 31.5 feet (29.5 actually, see below) to 391.5 (the IMU indicated height when outbound), tell me what you get.

In the same paragraph you just contradicted yourself. The Drone isn't 30 feet below its launch point. It's 2 feet above it (IMU altitude).

Edit to add: the reason I know for fact he was over 400' above agl is because at 1m 21.7s, he flies over nearly the exact same spot he would later land at. He is at 391.5 feet IMU altitude at that point. If he later came back to that spot at 2 feet IMU altitude, but the vision system detected the ground at 31.5 feet, then he was 29.5 feet ABOVE where his IMU altitude indicated. 391.5 feet plus 29.5 feet equals over 400 feet agl.

The OP already admitted he was flying irresponsibly. He flew well beyond VLOS, is it so hard to believe he was also relying solely on his RC screen to tell him the altitude not knowing it was only indicating the altitude above his home position? Is the OP even aware of the 400' limit?
 
Last edited:
Hi Everyone,

New here and not long got my first drone a Mini 2 SE. I have been flying it pretty regularly, almost every day the weather allows here in Scotland.
Had my first scare as I almost lost my drone on it's way home.

I had reached quite a good distance which I normally do but this day I almost had a heart attack. It ran out of battery on it's way home and it was a mission to get it back because of where it landed.

It initiated a RTH at 66% battery. Warm day for here 27c little to no wind but battery just kept depeleting on the way back. It was going down 1% a second.

View attachment 168144

It got back this far and landed in a very awkward place to retrieve.
My question is why did the battery start going down so rapidly and or why did it say 66% when initiating a RTH. Faulty battery readings?

View attachment 168145

Quite paranoid now about flying it any distance.
If you want to maximize your flight distance (not talking about flight range away from you), DJI recommends flying around 11 mph. Flying in sport mode (at 33 mph) will drain your battery fast. Keeping your speeds moderate may have saved enough battery to complete your flight and return.
If your signal strength drops into the orange, you should turn back before it hits red. You may lose control of the aircraft, and at a distance and beyond VLOS, you can't anticipate what will happen and respond accordingly.
When you see the battery draining fast, it's usually good practice to fly at a safe lower altitude in order to get the drone away from higher winds aloft.
 
  • Like
Reactions: rjwmorrell
In the same paragraph you just contradicted yourself. The Drone isn't 30 feet below its launch point. It's 2 feet above it (IMU altitude).
I didn't say the drone was 30 feet below anything.
I said that the land below the drone is 30 ft lower than the launch point.
 
I didn't say the drone was 30 feet below anything.
I said that the land below the drone is 30 ft lower than the launch point.
Then yes, the land is lower, which makes his flight above 400'
 
The ONLY record of your flight is the data logs. They will show that no time did he exceed 400'.
That's not how that works, so good luck with that one if the regulator wants to enforce the rules on you some day.

Edit: Scratch that, why am I bothering? You were the one complaining about the "VLOS police" earlier, clearly following the law doesn't mean much to you. I'll add you to my ignore list.
 
Last edited:
  • Like
Reactions: zen20009
Not by enough and not for long enough to get excited about.
I disagree, a 17 minute flight out to 4 km at potentially over 400 feet is certainly enough to get an air space regulator excited. It's the whole point of having the rules in the first place.

The rules are pretty clear in the UK and they don't make any exceptions in the Open class for the 400' or VLOS rules.

In Canada, the same under 250g drone would be fine to fly at over 400 feet and BVLOS (possibly), but that's not the case in the UK.

The OP recognizes their mistake and hopefully they learn from it.
 
  • Like
Reactions: zen20009
I had a similar incident with my Mavic Pro Platinum around 5 years ago. I realized I couldn't make it home, so I landed in a field. Some farmer who saw the map, recognized the location, and found it.
 
I have become curious, can anyone produce a csv of either the ground elevations or the AGL's, for each point in this flight?
Or can anyone tell me of a website that can produce the ground elevations from an appropriate file?
I have .kmz , .kml , and .gpx files, which would I use as the source file for such a website?
I think it can be done in Google Earth pro but I can't run Google Earth Pro and so far I haven't been able to find a website that does this for unregistered guests.
 
Last edited:
The ONLY record of your flight is the data logs. They will show that no time did he exceed 400'.

That's not how that works, so good luck with that one if the regulator wants to enforce the rules on you some day.

Edit: Scratch that, why am I bothering? You were the one complaining about the "VLOS police" earlier, clearly following the law doesn't mean much to you. I'll add you to my ignore list.

You'll be missing out on some valuable posts and comments if you do.
 
That's not how that works, so good luck with that one if the regulator wants to enforce the rules on you some day.

Edit: Scratch that, why am I bothering? You were the one complaining about the "VLOS police" earlier, clearly following the law doesn't mean much to you. I'll add you to my ignore list.
For one thing, I was trying to answer his question without being judgemental. The other, HOW DOES ANYONE WHAT THE ACTUAL ALTITUDE IS? At best, over flat ground or water, there can be a 50' difference. I REALLY want to know the answer for future reference.
 
For one thing, I was trying to answer his question without being judgemental. The other, HOW DOES ANYONE WHAT THE ACTUAL ALTITUDE IS? At best, over flat ground or water, there can be a 50' difference. I REALLY want to know the answer for future reference.
Google Earth gives a reasonably good indication.
Here's a plot of the terrain height along the drone's flight path outbound.

i-7nsjvtM.jpg

It shows that ground level rose significantly higher than the launch point.
The majority of the flight was well below 400 ft above ground level.
There was only a small section (approx 600 ft long) where the drone might have been marginally above 400 ft higher than the ground below it.
That section of the flight lasted approximately 20 seconds and the drone may have been approx 400ft +20 ft above ground level ... as I said, not really anything to get excited about.

For the benefit of the member that wants to argue/nag about infringement ... I'm not discussing the obvious distance of the flight.
 
Google Earth gives a reasonably good indication.
Here's a plot of the terrain height along the drone's flight path outbound.

i-7nsjvtM.jpg

It shows that ground level rose significantly higher than the launch point.
The majority of the flight was well below 400 ft above ground level.
There was only a small section (approx 600 ft long) where the drone might have been marginally above 400 ft higher than the ground below it.
That section of the flight lasted approximately 20 seconds and the drone may have been approx 400ft +20 ft above ground level ... as I said, not really anything to get excited about.

For the benefit of the member that wants to argue/nag about infringement ... I'm not discussing the obvious distance of the flight.
Given the inherent lack of precision of the barometer altimeter, there really is no way to discern EXACT altitude much closer than 50', correct?
 
Not just lucky to have a drone to fly, but lucky no aircraft or people were harmed. Drone was flown over the 400' agl limit, and being unseen, could have caused numerous close calls with aircraft.

What's so magical about the 400 number when it comes to AGL? If the FAA changes the limit to 500 tomorrow and everyone starts flying higher, will we all of a sudden start having a bunch of "close calls" with aircraft? Same thing with flying beyond VLOS or "way beyond" VLOS as you put it, why is that inherently so dangerous; when the FAA allows it eventually will the skies become "dangerous."
 
Lycus Tech Mavic Air 3 Case

DJI Drone Deals

New Threads

Members online

Forum statistics

Threads
130,112
Messages
1,549,402
Members
159,168
Latest member
hubb43