Merhaba arkadaşlar. Bu gün sisli havada spark uçurdum. 265 metrede sisin üzerine çıktı ve güneşi gördüm. bir kaç fotoğraf çektim ve aşağı indirmeye kara verdim fakat uygulama sürekli "landing" yaptı ve hızlı bir şekilde aşağı inmemi engelledi. Sanırım dronun sensörleri ıslandı yada sis tabakasını yer yüzeyi zannedip yüksekliği 0 metre olarak gösterdi ve "landing" konumuna geçti. Dronu tekrar tekrar bir kaç metre yukarı yükselttim. Yükselttiğim zaman 265m gösteriyordu, aşağı indirmeye çalıştığım anda 0 metre gösterip otomatik olarak "landing" yapıyordu. Bu şekilde cebelleşirken batarya tükendi ve dron 265 metreden aşağıya düşmeye başladı. Görüntü transferi kesildi. Kafamı kaldırıp bu hazin sahneyi izlemeye başladım. Birkaç saniye sonra spark görüş alanıma girdi. Pervaneler dönüyordu, çalışıyormuş gibi ses de çıkarıyordu, ışıkları yanmıyordu ve hızlı bir şekilde beton zemine çarptı. parçalandığını düşünüyordum fakat o da ne Spark hala tek parça ve sadece birkaç çizik var. Hemen diğer bataryayı taktım ve kontrol ettim. Hiçbir şey olmamış gibi kalkış yaptı, hiç bir sorun yoktu. Daha önce de sisli havada uçurmuştum, sorun yaşamamıştım fakat siz asla sisli havada uçurmayın. Bu bana büyük bir ders oldu.

Google Translate:
Hi friend. I blew spark in foggy weather this day. 265 meters above the fog and saw the sun. I took a few photos and decided to take them down, but the practice was constantly landing and preventing me from going down quickly. I think the sensors of the drone got wet or assumed the fog layer to be the ground surface and showed a height of 0 meters and went into the landing position. I've raised the drone over and over again. When I raised it, it was 265m, and when I tried to lower it, it was showing 0 meters and automatically landing. In this way, the battery was exhausted and the drone began to drop below 265 meters. Image transfer interrupted. I raised my head and started watching this sad scene. A few seconds later, spark came into my field of vision. The propellers were spinning, making a sound as if it were working, the lights didn't go on, and it quickly hit the concrete floor. Spark is still one piece and only got a few scratches. I immediately plugged in and checked the other battery. As if nothing had happened, departure made no problem. I've flown in foggy weather before, I've never had a problem, but you never fly in foggy weather. This was a great lesson to me.

It's very risky to fly above fog or cloud cover. You're lucky the outcome wasn't worst.

Hello and good day umitdemirel. I am sorry to read and to know what happened to your DJI Spark. If you feel that your DJI Spark is not performing or flying well on your next flights. Kindly please contact our DJI Support for further assistance at https://www.dji.com/support?site=brandsite&from=nav . In addition I will be posting some tips on how to use the DJI Spark's vision sensors properly. Thank you.

But that is a known thing, described in a couple of topics already
Fog, cloud, is or can be seen as ground , by the vision sensors.

The thing that might help, (hearsay, I never had this problem myself) is sport mode and not just lowering it, but flying it in circles, whatever route , around and downwards

Last New Years' Eve I had huge problems with the thickness of the smoke from fireworks at midnight. Was trying to go into landing mode at 180' feet! Thought a couple of times it was going to just drop straight down. Finally got it landed and keep it that way, I did end up with some awesome footage of the fireworks, but that smoke will mess with the Spark, just like fog and clouds.

You got two options:

Stay grounded if risk of fog, cloud or smoke.

Use Litchi (has the option to disable downward vision sensors). This setting will be saved in the Spark.
Either fly with Litchi or Go 4 app.
Be prepared against hard landings, especially the Low Battery Auto-land mode.
Hand catch preferred