I admit that helicopter doesn’t look like a threat. He’s landed and far down the runway.
Look what happens to the plane. 
That’s known as dirty air from turbulence.
News reports said the pilot did one go around to let the air settle. It wasn’t enough. The pilot reportedly survived.
I learned a lot from this video. I didn’t appreciate how bad dirty air can be.
Cite It also happens with race cars. Slipstream and 'dirty air' explained - Racecar Engineering
Small, single-engine Cessnas (which is what the crashing plane looked like, even if I’m not 100% sure) are surprisingly crash worthy. Not that I would ever want to crash anything, of course.
Wake turbulence is a big deal. It was certainly on my mind the time ATC slotted me between an F-16 and a B737 on the way into Fort Wayne, Indiana, with me in a tiny 2-seat Cessna, but fortunately everyone involved was competent and following directions so everything was fine.
I’ve run into a couple of pilots who hit wake turblence, including an FAA examiner who admitted that when he blundered into a blender he “screamed like a little girl”. He was high enough to recover without an issue, though. Other than perhaps requiring a change of underwear.
It happens with boating too, although there you can see most of the turbulence. It is a nasty experience in a race car, I don’t even want to imagine it in a plane.
I’m going to modify this. Imagine you are in a van, pulling a boat down the highway at 60 mph. Suddenly you are passed on the left, and then again on the right by fully loaded semi trailers doing 90 mph. Feel that suck? Scared when the boat trailer starts fishtailing? Now think about that in a plane, trying to land.
I remember we had been climbing for quite some time out of Heathrow heading for Egypt. Suddenly the jet dropped like a rock. 0G for so long. It stopped with a big bang as we grabbed air again. Passenger apologized for grabbing my leg so hard. That happened at high altitude with spacing observed. Pilot announced it as a wake turbulence issue.
Happened to my flight in 2002 to Germany, Lufthansa. I screamed like a not so little girl and grabbed mutually the little old lady sitting next to me who was also screaming.
Then we both got a shot from the steward in our section and had a stiff shot. Vodka as a sedative for the win!
Another helicopter/plane crash. Merion air disaster - Wikipedia
Killed John Heinz (ketchup) and John Kerry married the widow
Here’s a very detailed write up of the Merion crash.
All of Admiral Cloudberg’s crash analysis is excellent.
Yes, excellent analysis. A very good article indeed.
He usually writes one a week. I come across them in r/CatastrophicFailure. Check on Saturday afternoons.