Exceeded Max Altitude on RTH

[robee683]

I recently read a post where a member described problems associated with OA after initiating RTH when flying into the setting sun. I then realised that this could have been the problem I had during a recent flight.

I was flying in GPS mode, OA was activated and I initiated RTH. The controller displayed Going Home and the alarm was sounding but the AC didn't appear to be getting any closer. A bit of panic and after nearly two minutes the AC appeared overhead. At the time of RTH it was at 145m altitude and 78m distance. After RTH (and facing the sun) it flew a further 8m away and climbed to 169m. It then flew back to Home Point and continued to climb to 209m before orienting to the south and then landing at Home Point.

Shortly after takeoff I reached my Max Altitude of 30m and realised because I was recording a flight up a dam wall I needed to have a Max Altitude in excess of 120m so at that point in the flight I reset Max Altitude to 150m.

So my query is, on RTH when flying into the sun, will the OA cause the AC to continue to climb even beyond the Max Altitude setting?

I have uploaded the Flight Log to "msinger" and checked the viewer to see if it confirms that I had Max Altitude set to 150m but it doesn't appear to show this setting. Also the Flight Log shows a comment that Max Altitude of 209m was reached before descending to land. This makes it look like my error. However I can't believe I selected and odd number like 209 or that it could be a mistyping of 150. I did check the setting on the App before my next flight and it was set at 150m.

Also, I did not reset RTH Altitude and this would have been at 30m. Therefore the AC was not climbing to a very high RTH Altitude.

Look forward to your comments.

 

[robee683]

www.phantomhelp.com/LogViewer/W2L7SWTSREFWRLEJCB2B

 

[msinger]

The TXT flight log does not show the max altitude setting, but I can see the RTH altitude was set to 30 meters for the entire flight.

The entire RTH process looks very odd. I've seen the bottom sensors cause the Mavic to ascend beyond the RTH/max altitude while landing, but that doesn't seem to be the case here since your Mavic was not landing and those sensors were showing 0 feet at the time (as expected). I don't see anything in your log that indicates why your Mavic ascended two separate times on its way back to the home point.

 

[robee683]

Thank you for your input. Without confirmation of the Max Altitude Setting we are probably not going to get any further.

However re ascending during RTH it is possible that I had some control inputs once I started to get nervous (as it was out of sight above the trees) however I am certain I did not fly it away from the Home Point nor ascend after initiating RTH. I believe my inputs occurred about mid-way through the latter period of the return flight when I felt the AC should have been overhead. It was only 80m away at RTH and should have been overhead quite quickly but it took nearly two minutes.

Memory however is a fickle thing

 

[msinger]

Without confirmation of the Max Altitude Setting we are probably not going to get any further.

RTH should never exceed the RTH altitude though. Your Mavic was well beyond that altitude.

I believe my inputs occurred about mid-way through the latter period of the return flight when I felt the AC should have been overhead.

On the way back home, you weren't controlling either stick the majority of the time. The only thing you did is yaw the Mavic.

 

[BudWalker]

Here is an incident where, during an RTH, the Mavic climbed above the RTH max altitude. Litchi locked me out, crashed! The sun caused the Mavic to think there was an obstacle that it needed to climb over. But, in that incident the Mavic stopped at the Max Altitude, hovered until a critical low battery developed, and then attempted to land. In contrast in this incident the Mavic appears to be climbing above the Max Altitude.

I'll speculate that there could be two Max Altitudes. One a 500 meter DJI hard limit, and also a pilot defined Max Altitude which can't be set higher than 500 m. Further, that during an RTH the Mavic is limited by the 500 meter DJI hard limit. Not the pilot defined Max Limit.

 

[BudWalker]

There is this in the configLog stream of the .DAT
[ 500] => fly_limit_height
We don't know for sure what this means but it suggests that there is a 500 meter Max Altitude that won't be exceeded.

 

[znuttyone]

There is this in the configLog stream of the .DAT
[ 500] => fly_limit_height
We don't know for sure what this means but it suggests that there is a 500 meter Max Altitude that won't be exceeded.

Correct. 1640ft, 500M is for sure the max that DJI allows the AC to go and you cannot exceed it. Tested this with P4 and Mavic. if you set this to 200M.. then you cannot fly above it....but if "RTH Obstacle Check" is set, then it seems this setting will override the value you put in Max Altitude, ad it will keep flying higher upto the max of 1640ft/500M in an attempt to go over an obstacle ( .0400 code)

To answer the question on this thread. @robee683 had , if you have the setting 'RTH Obstacle check' set and flying into the sun, the mavic on the latest firmware (.400) will potentially climb up to 1640ft, regardless of the settings of the app for the RTH altitude or the Max Altitude...
First it will rise to the RTH altitude it it is not already above it, then it will start flying home, if the RTH Obstacle check is set, and the sun is in the flight path , low on the horizon, then the OA on the Mavic will think there is an obstacle in its path and will stop moving forward and start to climb, it will recheck and may or may not move forward, then climb again until it wither reaches 1640ft or no longer detects the sun as an obstacle. In the testing I have done, it can rise a 100ft and then make it home.. or depending on where the sun is , it will go all the way to 1640. You will see the controller flashing between Returning home and Obstacle with the controller beeping the entire time.
Best thing to do is flip to sport mode, if you are high enough with no obstacles in the way, then guide it home manually.

Also I run sunrise and sunset missions with Litchi and have noticed the AC can be flying backwards, with the camea and forward facing OA sensors facing the sun and the silly thing will still flash obstacle and slow the AC as it attempts to avoid the sun as an obstacle, even though it's flight path is moving away. This cause the AC to YAW back and forth as well as impact the speed, not good if you want to capture smooth video. I have started just turning OA off unless I am flying lower than tree tops or any obstacles in the area.

If anyone wants to test this, I captured a cookbook of steps to follow there. see Litchi locked me out, crashed!