I was visiting a dragon nest SSW of Whiterun, dont remember the name. Walked up the long stairs and saw it sleeping on the top of the architecture. An arrow woke his azz up up. He was just a "dragon" so i was having fun knocking him around, taking my time. He went back up into the air, and as he swooped down (still at 1/2 health) he just drove himself into the ground right into my companion and myself. He dug a trench 50 feet long and dirt was everywhere. He was not dead, but seemingly confused as he just lay there. I put him out of his misery. Very nice to see this after this long, i was totally surprised. Had not seen this before out of about 30 killed dragons.
So is this a just a rare occurrence? Or is it just this particular nest? as he seemed to drive himself into the ground, straight down the path to his alter?

It's not possible to physically change the terrain in-game unless it's quest related. You were more likely near a dragon mound/dragon burial site, and that was the "trench" you saw (it literally looks like a massive circular trench in the ground).

no not rare i ve seen this happen regular when they crashland , usually when they hit 40% ileft on their HP and are still in the air or when they try to fly away with less than 40% left
Always dramatic and epic to watch

Hmm.. I think you'll find the OP was correct. If a Dragons health drops below a certain amount while flying it will crash spectacularly, that includes digging a big dirty trench in the ground.

Intredasting... I always assumed that the terrain was static. Well, I've gotta test this out for myself

Yep I have seen this once. There was an almighty crash and I turned to see the Dragon I was fighting had dive bombed into the Guards that were fighting with me and had indeed scraged a kind of dirt trench thing.

It was the first dragon you fight outside Whiterun, on my third playthrough and it was the first time I had seen it in 200 hours of play.

Was pretty cool.

I see it happen often, although I do use quite a powerful bow on them mid-flight, so the odds of seeing it while doing that are somewhat higher.

Probably shouldn't have stated what you did like it was fact then

Seen it happen twice, but one of those dragons was still at 75% health when he did that, made it easier for me cause i was sword wielding with that character.

Gets annoying being a warrior and being left to wave and yell at a dragon in an attempt to get the retards attention.

Occasionally when Dragons are low on health they will make a crash landing into the ground, leaving a "trench" in their wake. They are not actually modifying the terrain around them, though - the "trench" is a separate mesh that overlays the original terrain, and it disappears once you leave the area.

It's a great effect but the first time I had it happen the bloody thing flattened me.

You know what's funny? They will go in a straight line always when they crash, so if there is a rock, or even a HOUSE or SHACK they will slide into into it and elevate over it. Rather hilarious.

They don't crash often. Unless you use Arrow or other ranged Attacks, the conditions are rarely created for them to do this. Which is lowered health and being airborne.

I've only seen this recently while playing, and before it only on some Skyrim trailers. Have they just actually added it to the game? It's still buggy though; they go through things into which they crash.

I've had this happen three times. The first time I was high on a mountain near Labyrinthian. The dragon took off to cicrle around me. I watched the dragon come in for what I thought was going to be a landing. Dirth everywhere I went running into the gaint dirt cloud looking for the dragon and almost fell off the mountain. Then I relized the dragon had crashed and was now behind me. Then I ran over to the dragon to continue the fight. This is also the first time I was able to jump on top of dragon to finish him off. It had such an epic feel to that fight. I also had this happen just outside of Whiterun and once more near Riften.

The ground does not stayed scared. When you return the ground will look normal again.

Yes I've seen this more than once. They come down like a plane landing with no landing gear and slide across the ground. There's a lot of dust/dirt that comes up and that's when they add in the trench so when the dust settles the trench is there. No real time deforming of terrain. it's a nice effect though. If you come back after a certain amount of time the trench will be gone and everthing will be back to normal, just no dragon.

It's pretty epic when they crash and then you get a cinematic kill on them too. Bonus if one of the dragon battle songs is playing.

Well, if the only affect in the whole game that alters terrain in any way is a scripted dragon crash landing, then yes, it still is pretty static

I have seen this once or I think maybe twice in many, many long hours of gameplay.
Yes it's real! They land like a UFO or something, like how superman's capsule landed when he was a baby...
Long furrow, dirt piled up on either side. Excellent!
Yeah my dragon was almost dead too.
But mine I recall was out in the open in a wide field (no altars or word walls etc. involved).
L8R

I've had them crashland a few times as well.

Thanks for the info guys. It was a great thing to see, just when I thought I had seen it all.
And while I woke it with an arrow, i had switched back to melee, my follower was plunking away though
Hope i find a few other little things like this. The game itself is quite repetitive, so this kind of find keeps me interested.

Unfortunately, it looks like they removed the wonderful glitch that would make them instantly take off while I was stabbing one, then promptly crash to the earth.

I have never seen a Dragon crashland like that. I thought the OP was mistaken. I did wonder what happens to a Dragon if it`s knocked out of the sky or even if it could be.

I look forward to seeing that at some point.

happens a lot to me and its not related to anything its just depends on terrain (if there is enough sapce for it to dive) and health and off course pure chance