Taking off after a storm.

[DeeRose]

My apologies for the long message. Just wanted to share an experience I had a couple of days ago with my zoom. We had thunderstorms in the area at night and soon after they passed, I decided to take a flight and see if I could catch part of the storm on video from afar. I took off from the exact spot I had taken off from many times before without any issues whatsoever in my driveway about 30 feet from a metal pole barn. I never take off without a home point established and GPS working which it was this time. As soon as everything looked good I took off and hovered about 5 feet, turned off the landing lights then she took off right into the pole barn. I don't know how it happened but the only thing that seemed to get broke was the propellers. Anyways, after spending the rest of the night running tests to make sure everything else was ok (what a freakin relief), I also discovered I had magnetic interference from a launch point that I had taken off from at least 50 times before without any issues. So, my point of this long windy message is to be careful when taking off directly after a storm because from what I can deduce, the residual electricity in the air coupled with the extreme moisture made a previously safe take off point not safe under certain circumstances and caused magnetic interference which crashed my drone. I learned a good lesson from this.

 

[kilomikebravo]

Dee: I may be completely wrong here but...using ANY concrete surface as a launch point is asking for trouble due to the steel rebar. I believe the reason you were able to successfully fly from that same location is because in those instances, you were just far enough away from the metal below to avoid a mag interference situation. But, on the crazy flight, I think your Mavic found some steel.

Should you peruse the M2 boards, you will find the following advice:

- Never takeoff from a concrete surface. If you have no other choice (unlikely,) hand launch from above the concrete. You really only need to be a short distance away from the ferrous metal to avoid the interference.

- Regardless of your launch point, when you power up everything and the aircraft has booted fully, compare the heading of the Radar Display arrow with the actual magnetic direction of the drone on the ground. Obviously, you need to be geographically oriented to know this but even if you don't have a pretty good idea of which way it's facing, you can always use the Compass app on your mobile device. Bottom line is, if the Radar Display is NOT pointing where you think it SHOULD be pointing, do not takeoff! Move to another location and repeat until the two DO line up with each other and you don't have any error messages. Many people have sent requests to DJI to get them to modify the "mag interference, move or calibrate" prompts to something more accurate and useful. Calibrating the compass will not help in the VAST majority of situations...MOVING WILL help in almost all cases.

 

[DeeRose]

Dee: I may be completely wrong here but...using ANY concrete surface as a launch point is asking for trouble due to the steel rebar. I believe the reason you were able to successfully fly from that same location is because in those instances, you were just far enough away from the metal below to avoid a mag interference situation. But, on the crazy flight, I think your Mavic found some steel.

Should you peruse the M2 boards, you will find the following advice:

- Never takeoff from a concrete surface. If you have no other choice (unlikely,) hand launch from above the concrete. You really only need to be a short distance away from the ferrous metal to avoid the interference.

- Regardless of your launch point, when you power up everything and the aircraft has booted fully, compare the heading of the Radar Display arrow with the actual magnetic direction of the drone on the ground. Obviously, you need to be geographically oriented to know this but even if you don't have a pretty good idea of which way it's facing, you can always use the Compass app on your mobile device. Bottom line is, if the Radar Display is NOT pointing where you think it SHOULD be pointing, do not takeoff! Move to another location and repeat until the two DO line up with each other and you don't have any error messages. Many people have sent requests to DJI to get them to modify the "mag interference, move or calibrate" prompts to something more accurate and useful. Calibrating the compass will not help in the VAST majority of situations...MOVING WILL help in almost all cases.

Thanks Kilo. Rebar was one thing I hadn't thought about. One thing I did notice that night was having to re calibrate the compass every time I powered it up which I don't usually have to do. Didn't seem to matter where I was though. That should have been a red flag I suppose. We have an asphalt driveway with a cement apron so I will make sure to take off from the asphalt from now on. It definitely would be helpful if mavics had better interference notifications ahead of potential crash scenarios.

 

[kilomikebravo]

Dee: Yes indeed, that should have been a HUGE "red flag" but, you didn't lose your baby and most importantly, (just like me on my concrete driveway,) you learned from the experience. That said, I have learned SO much more from the experienced and technically-savvy folks on this Forum. That knowledge is worth more than the drone itself to me.

I never considered asphalt with a concrete apron but your decision to now steer clear of the rebar should solve your issues. I'd bet a LOT of money that ALL those mag interference-move or calibrate prompts were ALL due to rebar or some other ferrous metal very near the drone.

Let's all hope that DJI listens and fixes those warnings to give the operator good information, not misleading information.

 

[DeeRose]

Dee: Yes indeed, that should have been a HUGE "red flag" but, you didn't lose your baby and most importantly, (just like me on my concrete driveway,) you learned from the experience. That said, I have learned SO much more from the experienced and technically-savvy folks on this Forum. That knowledge is worth more than the drone itself to me.

I never considered asphalt with a concrete apron but your decision to now steer clear of the rebar should solve your issues. I'd bet a LOT of money that ALL those mag interference-move or calibrate prompts were ALL due to rebar or some other ferrous metal very near the drone.

Let's all hope that DJI listens and fixes those warnings to give the operator good information, not misleading information.

The funny part was that I don't remember seeing any notifications on the screen that night but it was late and I was tired so who knows. Yes. We live and learn and hope our babies don't get too hurt in the process. After I heard it crash against the pole barn, I thought it was all over but we live to fly another day. Cheers.