Barometer suddenly drops


I am using Cube Orange + copter 4.0.7.
In this recent flight test, at landing phase in Loiter mode, when the drone was at 50cm height from ground, it lost its height and fell to the ground (no damage!)
I check the log and see that barometer was dropped right before the impact.

Bin file:

Can anyone please help to figure the cause whether it is from hardware or firmware.
Thanks in advance,

If the copter is big enough then 50cm is probably low enough for you to get a pressure blip off the ground and confuse the barometer.

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Hello @andyp1per, thanks for your reply.
50cm is estimated from the end point of landing leg to the ground. So in the log, you can see that the height calculated by the barometer decreases sharply (which is not desired by the by pilot).
I am not sure what you mean by “blip off” (sorry for my English) but I have never experience this situation before.

More information: my Cube is inside the cover box with 1 6mm diameter hole only.
Hope that you can advise.

I have to say it looks like ground effect to me - you get the same pattern at takeoff, but you are right baro inside the cube should be largely unaffected.

SW: 4.0.7 copter
HW: Cube Orange
flight logs, outdoor
ightware SF02 Rangefinder
flow sensor
drone weight is 1.8Kg

We experience drone oscillating (up and down) suddenly in Loiter flight mode outdoor. Hope to get a solution to this problem. we notice barometer values can go below 0, far zero and fluctuate badly.


Did you face the same problem in AltHold mode?

do not think so, may be did not move fast enough both roll and pitch.
A good example of barometer readings

Just test it in AltHold mode to observe. Let’s apply some roll and pitch with >= 4m/s. If this did not happen in AltHold or any non-GPS modes, go to Loiter again and check if reducing these parameters a half will help or not: PSC_POSZ_P and PSC_VELZ_P.

I can give a try and report again. Right now, my guess is that the Loiter mode brake algorithm could be the cause or the barometer is faulty.

If you are sure the problem started from AltHold mode, let’s increase this parameter a bit when you are in Loiter EK2_ALT_M_NSE

EK2_ALT_M_NSE was 3 previously and experience height drop when roll and pitch. I increased to 5 and the height is much stable when roll and pitch. we do not experience hover hold issue all along after tune using autotune.

I have an indoor flight log with the same parameters, small flying space, log looks fine to me except that the CTUN.BAlt is way below 0.

we do not have an issue with AltHold flight mode, very stable both indoor and outdoor. So, we decide not to change these two vlaues.

These two parameters are for GPS modes (Loiter,…), not for AltHold as I said in previous post.

Oh, noted. But we set EK2_GPS_TYPE,3.

with the same parameters, did a retest outdoor hope to repeat the problem.
Also to see if we need to reduce PSC_POSZ_P and PSC_VELZ_P by half.

Not manage to get the up and down oscillation in Loiter flight mode but in FlowHold flight mode. Once oscillate, I have to quickly find the descend timing to land the drone.

Flight log.