The promised sunny and calm weather this week-end turned out to be calm, yet foggy. Really foggy.

The visibility at ground level was about 50 meters, so I decided to give it a go. The flight consisted of a few short foreys around the neighbourhood at an altitude of 50-70 meters, followed by an experiemt, where I climbed above the take off spot, straight up to 120m, noting how the view of the ground gradually disappered, also noting at which altitude I would lose sight of Mavic. The flight was done with the new propellers.

Here is a video of a few moments form the flight (using SkyPixel as that's still the easiest platform to upload to directly from DJI GO)



Here are a few points of interest to note:

• Fog shifts quickly. A spot where you for a second may have a good 200m of visibility can quickly turn into 30-40m.
• I could hear Mavic up to 50m up with the new props when hovering, afther that it went completely silent.
• I have a white Cree strobe light attached to the bird. While I lost sight of the Mavic's silhouette at about 50m above me, the blinks from the strobe were visible until Mavic was about 70-80 meters up.
• It is very easy to become disoriented in the fog. I had to switch to map view and point camera straight down on many occasions to get my bearings, even though I was never further, than 250m away and over a well-known area.
• Having a helipad on the ground (orange side up) is helpful when returning at altitude - it was the last thing to disappear from view in the straight up test.
• After the flight I noticed fine droplets of condensation from on the following areas: upper and front surfaces of the arms, and on the upper rear of the body, where white DJI logo is located. The rest of the bird was dry. In sub-zero foggy conditions such condensation can freeze, build up and result in added weight.
  

Doesnt Look to good ;)

Very nice.

You rather use the radar instead of the map. It is much easier to re-orient yourself and yes fog flying is dangerous especially in the winter so I try not do it but sometimes you can't resist

I am the E Posted at 2017-11-6 11:16
Very nice.

You rather use the radar instead of the map. It is much easier to re-orient yourself and yes fog flying is dangerous especially in the winter so I try not do it but sometimes you can't resist

Thanks for the hint.
Radar and its usefulness was largely overlooked by me. I actually first started to look closer at it after that flight.
And, yeah, when conditions are borderline safe, it's hard not to challenge oneself to a flight
I plan on doing some flights during winter, so this fog flight was a valuable lesson with regard to condensation.

Speaking of borderline safe...
I had a case of multiple "Compass error" and "Speed error" faults on the last voyage that day. There is a mobile phone antennae mast camouflaged as a tree approximately where I drew a red circle in the image below. I've flown above and past the spot on multiple occasions before. But then I would also climb to about 90m before proceeding due to the hillside. This time the fog kept me at 50 meters, meaning I was only 20 meters above ground at that particular spot.
I didn't realise it at first (only thought of the antennae in the post-flight analysis), but it looks like I flew into the radio emitter beam.
The strange thing here was that the AC did not switch to ATTI mode (like it did once), but continued in P-GPS. As soon as I registered the error, I let it hover and gained a bit of altitude, though not much so as not to lose ground out of sight. After it drifted a bit backwards and sideways (the small loop), Mavic got its compass bearings back, and I proceeded returning home in manual mode. In retrospect, an attempt to RTH in that condition may have sent Mavic in a completely different direction, resulting in a fly-away.

Nice one! I had a similar experience not so long ago and I can relate to what you wrote at 100% especially about switching to the map. I have never tried the radar though, guess I should give it a look. Oh, and of course, I found that flying closer to the ground was a good way of getting usable footage in such conditions (If you're curious: https://forum.dji.com/thread-117616-1-1.html)
Thanks for sharing!

Pretty courageous BumblerBee and glad it flew without a hitch. I always wondered how the MP would behave flying in the fog. My concern would be the condensation in the MP.

What's this about radar?  How does one engage that?

StanfordWebbie Posted at 2017-11-6 17:59
What's this about radar?  How does one engage that?

It's on the lower left side of the mobile screen. You can tap on the round radar icon to change the viewing options.

Ah, I wondered if that was what you meant.  As I think more about it, you're probably calling it "radar" because it sort of resembles a radar screen.  I was thinking (at first), "Do these folks actually think that their quad has radar?".    Silly me.  

Nice video.
Fog is dangerous and beautiful

Nice flying. It was cloudy the other day and I decided to try to fly above the clouds. It too around 95m to "reach" the cloud and another 330m to get over the clouds.

BumblerBee Posted at 2017-11-6 12:03
Thanks for the hint.
Radar and its usefulness was largely overlooked by me. I actually first started to look closer at it after that flight.
And, yeah, when conditions are borderline safe, it's hard not to challenge oneself to a flight

I hear you mate. One more thing I always canvass the area before I fly around. These pesky Cell Towers are all over the places now.

I use: http://www.cellreception.com/towers/

to search for cell towers in the areas. Put the city or zip code and google map gets populated!

I am the E Posted at 2017-11-7 12:44
I hear you mate. One more thing I always canvass the area before I fly around. These pesky Cell Towers are all over the places now.

I use: http://www.cellreception.com/towers/

Thanks, though that site is for US only, and not worldwide.
I know of that tower (and about 6 other in the immediate vicinity of where I live), but I usually have enough clearance over them. This time the fog kept me closer that what was apparently advisable.

Great video - just be careful flying in any type moisture

BumblerBee Posted at 2017-11-8 10:46
Thanks, though that site is for US only, and not worldwide.
I know of that tower (and about 6 other in the immediate vicinity of where I live), but I usually have enough clearance over them. This time the fog kept me closer that what was apparently advisable.

Got you! Be careful