According to a tweet from Flightradar24, approximately one hour into the flight, the aircraft was in cruise flight at 29,100 feet when it abruptly lost altitude, entering a steep descent. The aircraft appeared to recover briefly at approximately 8,000 feet, then it reentered dive.
Some sources claim the sudden nose-dive was intentional because of manual crew input, but to me it sounds like the crew reacted to something extremely strange happening and tried to correct it ("let's click the AUTO button and get some rest. Oh shit."), especially since the aircraft "appeared to recover briefly at approx. 8,000 feet". Sounds a lot like all the other Boeing 737-x crashes where the pilots were surprised by the sudden nosedive, wrestled manual control back, only for the systems to kick in again into a dive.
I post this not as news, but as a point of interest for me personally.
MCAS was invented specifically for the 737 MAX 8 and 9. It's not present on the 800.
After reading all the Admiral Cloudberg articles and watching all the videos on the Mentour Pilot youtube channel, I can fairly confidently say that there are a huge number of potential causes for a sudden loss of altitude, most of them initiated by human failure.
It's funny. Most of the time if someone said "watching this YouTube channel has made me very confident in my opinion" my Dunning-Kruger detectors would be in high alert. But Cloudberg and Mentour are just so very good and taking complex, highly technical systems and breaking them down in a way that makes sense to someone with little to no knowledge of airplanes.
Kyra and Petter are both amazing