Mavic Air 1 - Low Altitude hold issue

[Atomwild]

Looks like there is still a problem. Looking at FLY061 at time 513 secs the Flight Controller incorrectly thinks the height is increasing as shown by IMU:alti (blue plot). The FC responds by descending as shown by pressure, GPS:heightMSL and ultrasonic height. For the next 6 secs the FC thinks the MA is ascending and continues to command MA to descend.
View attachment 133251

I had stated previously that the pressure sensor seems to dropout when the AC descends below a pressure altitude of -7.8 meters. But, the dropouts occurred in this flight at a different pressure altitude (+7.8 meters). I took a look at some other MA .DATs and found more examples of these dropouts and at different pressure altitude heights. Additionally, those flights did not exhibit incorrect IMU:alti data. From this it's obvious the dropouts are not the cause of the problems seen in @Atomwild 's flights.

The common denominator in these flights is that the ultrasonic height data shows the dropout happening as the MA is descending below 0.5 meters above the ground. My current theory is that the drop in pressure altitude is due to a momentary pressure increase between the downward prop thrust and the ground. Just a theory.

Thanks BudWalker, Slup and RGallant for your thorough analysis and discussion on my flight data. This low flight issue is an infrequent occurrence and I'll manage that or send in to DJI. Again many thanks.