M2P Descending Crazy Slow

[Parkerjh]

On several flights today, my descent was only about 1' every second or so.
I had been using DroneDeploy and figured it was an app issue.
Then, switched to DJI Go with the same results.
Happened in P, Sport and Tripod modes.
Just crazy slow at full stick down.
Weirdly, when the drone finally got to 10' or so, normal controls resumed.
So the first time it happened, I was full throttle down trying to land before battery died and when normal operations kicked in, I was flying full speed at ground and nearly crashed.
The next few flights, I was careful not to full stick down as I got close to ground.

I do see a message in the log "Downward altitude sensor data error."
Not sure that is related or not.

Any ideas what could be causing this erratic behavior?

 

[Meta4]

I do see a message in the log "Downward altitude sensor data error."
Not sure that is related or not.

It's very much related.

Usually this sort of problem is caused by a problem with the VPS sensors, and that's what caused your problem.
Your drone was descending at normal speed while up high, but below 270 ft the rate of descent slowed significantly.
From 73 feet, it dropped below 2 ft/sec and from around 40 ft, it was 1 ft/sec.

Your VPS sensors have a limited range (max 66 ft) and when out of range should record nothing.
Looking at the height above ground that is showing for the VPS when the descent starts to slow (with the drone 240 feet up), the VPS sensor is indicating that the drone is 12 feet above the ground.
Later with the drone 84 feet up and descent slows to 2 ft/sec, the VPS is indicating that the drone is 4 ft above the ground.
When it's 44 ft up, VPS indicates a height of 2.6 ft.

This is landing protection acting to prevent the drone slamming into the ground, but with false VPS sensor data.
Sometimes this is caused by fog that can fool the sensors or a badly fitted accessory blocking the view of the VPS sensors.
If neither was the cause in your case, try cleaning the VPS sensors and recalibrating them.

 

[Parkerjh]

It's very much related.

Usually this sort of problem is caused by a problem with the VPS sensors, and that's what caused your problem.
Your drone was descending at normal speed while up high, but below 270 ft the rate of descent slowed significantly.
From 73 feet, it dropped below 2 ft/sec and from around 40 ft, it was 1 ft/sec.

Your VPS sensors have a limited range (max 66 ft) and when out of range should record nothing.
Looking at the height above ground that is showing for the VPS when the descent starts to slow (with the drone 240 feet up), the VPS sensor is indicating that the drone is 12 feet above the ground.
Later with the drone 84 feet up and descent slows to 2 ft/sec, the VPS is indicating that the drone is 4 ft above the ground.
When it's 44 ft up, VPS indicates a height of 2.6 ft.

This is landing protection acting to prevent the drone slamming into the ground, but with false VPS sensor data.
Sometimes this is caused by fog that can fool the sensors or a badly fitted accessory blocking the view of the VPS sensors.
If neither was the cause in your case, try cleaning the VPS sensors and recalibrating them.

thanks, that all makes sense.
But is the VPS disabled in Sport Mode?
If so, shouldn't I be able to descend at normal rate?

 

[Meta4]

But is the VPS disabled in Sport Mode?
If so, shouldn't I be able to descend at normal rate?

No .. VPS continues to work in Sport Mode.
It's the forward obstacle avoidance that is inactive in Sport Mode.

 

[Parkerjh]

No .. VPS continues to work in Sport Mode.
It's the forward obstacle avoidance that is inactive in Sport Mode.

Great thanks, that explains it

 

[Fuzzyants]

Has this issue been resolved? I've also discovered the same thing for my MA2. The issue has been present for over a couple months now. At first I thought it might be solved by an update however the issue still persists.

Here's my flight log. For this specific flight I took off at a higher elevation and needed to drop approximately 400m in elevation to get down to the area I need to snap some photos of. I found myself burning all of the battery trying to decent to the elevation I need because of this weird slow decent issue.

Any help is much appreciated!

 

[Meta4]

Has this issue been resolved? I've also discovered the same thing for my MA2. The issue has been present for over a couple months now. At first I thought it might be solved by an update however the issue still persists.

Here's my flight log. For this specific flight I took off at a higher elevation and needed to drop approximately 400m in elevation to get down to the area I need to snap some photos of. I found myself burning all of the battery trying to decent to the elevation I need because of this weird slow decent issue.

Any help is much appreciated!

Your flight data looks like this:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

It shows that the VPS sensors were causing the issue.
They started the flight reading properly, but by about 2:20 they were starting to throw incorrect height readings and starting to slow your descent.
By 2:38.3 the VPS height is indicating 10 feet above the ground below the drone and descent has slowed to half the normal rate.
And by 4:14.1 the descent rate is down to less than 1 ft/sec.
For most of the rest of the descent VPS indicates a height of 2-3 feet.

If there was no physical blockage of the view of VPS by fog or condensation on the sensor windows, the sensors appear to be malfunctioning.

 

[Fuzzyants]

Your flight data looks like this:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

It shows that the VPS sensors were causing the issue.
They started the flight reading properly, but by about 2:20 they were starting to throw incorrect height readings and starting to slow your descent.
By 2:38.3 the VPS height is indicating 10 feet above the ground below the drone and descent has slowed to half the normal rate.
And by 4:14.1 the descent rate is down to less than 1 ft/sec.
For most of the rest of the descent VPS indicates a height of 2-3 feet.

If there was no physical blockage of the view of VPS by fog or condensation on the sensor windows, the sensors appear to be malfunctioning.

Thanks for the quick answer!

Looking at the bottom of my MA2 it doesn't look like there's any dirt, grime or fog blocking the VPS and I should add that I have just received this new MA2 back in May as a replacement through DJI Care. Do you think I could recalibrate it in any way to solve the problem? Or would this just indicate a faulty unit all together.

 

[Meta4]

Thanks for the quick answer!

Looking at the bottom of my MA2 it doesn't look like there's any dirt, grime or fog blocking the VPS and I should add that I have just received this new MA2 back in May as a replacement through DJI Care. Do you think I could recalibrate it in any way to solve the problem? Or would this just indicate a faulty unit all together.

It's hard to know without more information.
Does this problem consistently show up every flight or was it something related to the place/time where this flight occurred?
Was the air clear or was there fog?

The manual gives only brief details about calibrating the sensors on p16-17 here:

https://dl.djicdn.com/downloads/Mavic_Air_2/Mavic_Air_2_User_Manual_v1.6_enIII.pdf

 

[Fuzzyants]

It's hard to know without more information.
Does this problem consistently show up every flight or was it something related to the place/time where this flight occurred?
Was the air clear or was there fog?

The manual gives only brief details about calibrating the sensors on p16-17 here:

https://dl.djicdn.com/downloads/Mavic_Air_2/Mavic_Air_2_User_Manual_v1.6_enIII.pdf

This has been an issue that I have noticed on all my flights in the past few months, it hasn't been a big issue since I've always thought it was going to be fixed and could just be a small glitch. So I waited it out until I couldn't anymore.

The weather that day was sunny with clear skies, no fog or any moisture in the air. I will take a look at the calibration guide and see if I can do anything there. Thanks!