So if the radar pointer is off how do I correct the yaw value? I did get a compass warning before take off on the beach, so I moved the backpack and AC 10' away and the compass warning cleared.
IMU & Compass Warnings
- Thread starter cneedelman
- Start date
So if the radar pointer is off how do I correct the yaw value? I did get a compass warning before take off on the beach, so I moved the backpack and AC 10' away and the compass warning cleared.
You corrected by moving away from the backpack. There evidently was mettalic interference which threw the compass off. When you moved did the icon correct as well? It should have. Or did you notice?
I'm not sure what you're describing about the radar pointer. Is it an inconsistency between the pointer and what you see when you look at the P4? Or, is it an inconsistency between the pointer and the N symbol?
Rather than using the radar pointer a better choice is the heading indicator in the map display. Using the radar display can be tricky and produce erroneous results. Check out
Mavic Air fly-away with no luck to find it.
You previously posted this
I'm not sure what you're saying here. Is it that the North point wasn't actually at the top when the tablet was facing true north? If so, calibrating the P4 compass won't affect this. A tablet compass calibration is necessary to fix this.
There is no guarantee that the FC will detect a compass problem prior to launch unless the magnetometer readings are seriously off normal because, unlike the operator, the FC has nothing to compare to and so no way to know which direction the aircraft is really facing.
And if the directional arrow is pointing in the wrong direction there is no way to fix it at that location - you need to move to a different location that does not have a distorted magnetic field. In this case, if the source of the problem is your backpack, simply moving that is not going to help. I suggest that you check it for magnetic interference and consider an alternative launch platform.
DJI does a poor job of wording its error messages and makes virtually no effort at all to explain how flight control works, but it is still surprising how difficult it is to convey to people that it's not bad compass calibrations causing these problems.
Just a comparison in the discussion. Granted this is a Litchi screen shot but both the map and the radar icons point to the southeast, which in this particular quick flight from quite a while back is spot on as to the direction that the Phantom was facing before takeoff. Just for what it's worth, I always check both before flight.
I'm not familiar with Litchi. Can you expect that both icons will point the same - regardless of tablet orientation? If so, that's different from the Go App.
Oso
Premium Pilot
My understanding is that the diagnosis was magnetic interference from the backpack or something in the backpack.
Post 11 from Meta:
"I would not expect this from launching from a backpack on the beach unless you had a substantial steel item in the part of the backpack you rested the Phantom on to launch."
Post 11 from Meta:
"I would not expect this from launching from a backpack on the beach unless you had a substantial steel item in the part of the backpack you rested the Phantom on to launch."
Oso
Premium Pilot
Of course I recommended a compass calibration in a clean area. He said he had recalibrated in a then suspect area thinking it would fix the compass error. I would all day long recommend moving to a known good area to redo a suspect calibration if nothing else but to have confidence in the gear and to eliminate a variable. I'd hope that most here would recommend the same.
Tablet orientation I cannot confirm, although while facing the Phantom ( As you should for Antenna Orientation), Yes they should match. This screen shot is a mission return from the WNW to SSE.
But, you can't get a flawed compass calibration by calibrating in a bad location. At least, there has never been case with at least some compelling evidence. It's a myth - it doesn't happen. Unnecessary calibrations aren't a problem per se. The problem is that promoting a compass calibration makes it difficult to focus on the real problem and solution, this thread being a good example of that.
If the problem was the backpack then the compass calibration will have been fine (unless it was done in the backpack). And as @BudWalker mentioned above, a compass calibration in a locally distorted magnetic field will fail because the external field will not be constant. As I said - the fixation with compass calibration distracts from the root cause of these incidents.
Oso
Premium Pilot
We are not physically standing beside the folks who post here, so we never really know what they are doing or know fully their surroundings. In these "compass error" cases when people have already calibrated in suspect conditions, my opinion has been that the greater good is served by simply recommending a calibration in a clean area to ensure a good baseline, leaving the calibration alone from then on, and continuing to explain over and over as we do that calibrating is rarely the fix for that error. That is what I will continue to recommend. Of course feel free to recommend something else. All we can do is provide data points to help people to decide what is best for them.
Fair enough - that's good advice as long as it doesn't fuel the widespread misconception that a bad compass calibration causes these problems in the first place.
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