Yes, Confirmed, seriously annoying!

Related (but NOT duplicate) of #2149.

True duplicate of closed tickets #1211 and #1883

The player can only stand on very steep terrain. Entering this terrain in any other stance will cause the player to stand up. On extremely steep terrain, the player will slide down the hill on his feet.

I don't think the current solution to steep terrain is very realistic, but I can not think of an obviously better solutions either...

This issue was processed by our team and will be looked into. We thank you for your feedback.

Please keep the issue monitored to see when it is fixed.

@ceeeb: the default stance on very steep terrain, should be prone. It would simulate climbing or crawling on both legs and arms. Sliding down would also happen in the prone position, possibly with rolling effect. If rolling, the speed would increase, until the character hits something or rolls down to a flat terrain. Character could be injured or killed in the process, exactly as during an accident in the mountains.

Can you write coordinates of some place, where this issue happens? Write into watch field "position player" in debug console [Esc]. Number which will be shown are your coordinates. Thank you.

This occurs at any point of the island which has a slope of the ground surface is more than about 30-40 degrees. I believe that a game character under any circumstances should not perform any actions without my orders. I think that this is not a bug, it's a decision the developer is very similar to the one that can not be shot from a grenade launcher in the supine position. This is a very strange decision in my opinion.

Northweast from Camp Rogain
I was stalking guard tower on vehicle showcase:
4956.01,5943.38,0.00273132 (crawling on a heading 222 deg)
another walkthrough:
4965.29,5956.11,0.00332642 (heading 230 deg)
Here I was spotted and killed by the guards in the tower.

Cliffs between Agia Marina and Airbase
I was crawling up the hill to a sniper position:
2448.11,5767,-0.000518799 (heading 153 deg)

Northweast from Camp Tempest
I was exiting from water there on scuba showcase:
1830.55,3621.33,-0.00211859 (heading 128 deg)
It's a VERY steep terrain between the rocks, which could be possibly navigated, with the help of some gear. Even a knife sticked into the soil, to create a supporting point, would do. It would be a slow upward drag, on your belly, with both arms and legs pulling you up. But in Arma3 you can't crawl there, while walking uphill is possible.

North from Camp Rogain
Another find from vehicle showcase, I was crawling there to stealthy sneak into the camp:
5016.9,5968.1,-9.15527e-005 (heading 172 deg)
After my character stood up, I quickly dashed forward and got prone, only to stand up again a few steps further:
5016.57,5960.8,-0.000274658

In the current Dev version, character stands up only to a crouch, but it's still wrong. The ideal outcome, when encountering too steep or otherwise impassable terrain, would be to stop the character's movement there and leave up to player's choice, whether to change stance or to move back and find another way.

Default movement stance on a very steep terrain should be prone, when moving up (climbing) or down (sliding). When moving across such very steep terrain, it should be possible to walk or crouch-walk, but with a possibility to slip and fall down, especially when moving fast.

behaviour changed so the character goes just to kneel. This is best we can do, allowing prone on big slopes causes even more severe problems.