Labroides
Core User of DJI
Flight distance : 9991457 ft
Australia
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Olivier Vietti- Posted at 2017-9-23 23:17
but it is not a hazzard, although it only affects a few people, the bug exists, I have to say else found a bug with the clock, it is therefore possible that the syncronization gps does not just right and misleads the drone, attached the file of the flight in question impossible to link the flight "blocked by dji"
https://www.dropbox.com/s/qcjdz8 ... 9-35-54% 5D.txt? dl = 0
That makes interesting reading.
I'll try to explain what I see in the flight data that DJI didn't explain very well.
To go back to your original report of the loss of the P4 pro, you said...
Lastly during an exercise with the fire brigade, the connection with the drone was lost without possibility of recalling the drone, which left full south at high speed. The incident was submitted to DJI, who today writes that they see a loss of connection with the indication of the 77% battery and the position of the sleeves. DJI offers a discount of 30% in the form of coupon, it is unacceptable, I think that any machine can have unfortunately a computer problem or hidden hardware that can not be detected by the end user. I am reassured that this drone apparently did not cause damage to third parties on the ground ... We are also strongly disappointed DJI after-sales service. I hope this will not happen to you in your life.
Looking at your flight record, it shows that you flew out over a large lake and had it flying in P-GPS and Sport modes.
The last few seconds of the flight record are what is important because up till then everything is quite normal and there are no error indications.
At 7:50.5 the Phantom is 3600 feet out on the lake and flying at 35 mp in Sport Mode.
The IMU altitude is showing 18.7 feet altitude above launch point which was at or close to water level.
you have been flying at moderate fast speed and push the right stick hard forward and quickly get to 40 mph.
At 7:54 when the the flight record ends you still have the right stick hard forward.
Looking back at your altitude readings, there are some big differences between the IMU altitude and the VPS altitude.
At 7:50.5 you had IMU alt = 18.7 ft VPS = 11.5 ft
At 7:53.6 IMU = 20.7 ft VPS = 6.2 ft
It's usual for the IMU altitude accuracy to vary as the Phantom warms up during a flight so we can not rely on the IMU altitude to give an accurate height for the Phantom.
We also know that VPS is not accurate for use over water or reflective surfaces and is strongly affected by the tilt of the Phantom when flying fast.
Your Phantom was flying with a pitch angle of 35°-38° just before the flight record ends.
The specs tell us that the VPS has a velocity range of ≤31 mph (50 kph) at 6.6 ft (2 m) above ground.
This is because at greater speeds, the tilt of the Phantom makes the VPS altitude measurement inaccurate as it is designed to give a reading of the vertical distance below the Phantom.
Page 29 of the P4 pro manual gives a list of conditions where pilots should use caution with regard to the VPS:
Operate the aircraft with great caution in the following situations:
a) Flying over monochrome surfaces (e.g. pure black, pure white, pure red, pure green).
b) Flying over a highly reflective surfaces.
c) Flying at high speeds of over 31mph (50kph) at 2 meters or over 11mph (18kph) at 1 meter.
d) Flying over water or transparent surfaces.
e) Flying over moving surfaces or objects.
f) Flying in an area where the lighting changes frequently or drastically.
g) Flying over extremely dark (lux < 10) or bright (lux > 100,000) surfaces.
h) Flying over surfaces that can absorb sound waves (e.g. thick carpet).
i) Flying over surfaces without clear patterns or texture.
j) Flying over surfaces with identical repeating patterns or textures (e.g. tiling).
k) Flying over inclined surfaces that will deflect sound waves away from the aircraft
In another post you said ....
In fact, there were just 30 firefighters who saw the drone sailing at high speed due south while I had my hands placed towards the sky to show that I no longer had control of this drone, and for the data they are in the remote control and the recording stops where the drone takes flight ...
Perhaps Swiss firefighters all have exceptional eyesight but I'd still be surprised if they can clearly see a Phantom close to the lake's surface at a range of 1100 metres.
I mostly fly over water and I know that I have trouble keeping a clear view at half that distance.
Clearly some of the incident description does not match the story that the data is telling us.
The data is more reliable than the opinion of someone that is unsure of what they are seeing and/or doing.
So what we can be sure of is:
You flying very fast, very close to to the lake's surface, 1100 metres out.
The altitude indications cannot be relied on for accuracy but they do tell us that you were very close to the water.
The Phantom appears to be responding to your control inputs.
See 7:16 when you changed direction and brought the drone lower for an example.
We regret that Dji makes no guarantee, we have decided to inform our partners of the low reliability of your products in order to prevent an accident and especially to avoid our bad experience Dji ...
Perhaps you should inform your partners that they should not allow you to fly drones for them.
Sometimes the flight record shows evidence of a malfunction.
Sometimes it doesn't. This is one of those times.
It appears that the problem was the operator and not the drone.
It is most likely that you "lost control" of the drone because you flew it into the lake at high speed and too far out to be able to see it. |
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