I'm going to speculate and predict what happened to Asiana QZ8501.

[TorchTheWitch]

4. they requested to climb but were denied

because of air traffic at the time above them. Five minutes later contact was lost with the plane. Since they couldn't climb they had no choice but to continue on through the storm. Because of the bad weather a multitude of things could have happened. We aren't going to know in any case for a long time, and the plane has to be found first. More than likely it's at the bottom of the sea, but at least this time they know in what area it would have gone down. Sadly, no one would have survived.

https://sg.news.yahoo.com/indonesia-searches-java-sea-missing-airasia-plane-relatives-022153350--finance.html
<snip>
Flight QZ8501 was travelling at 32,000 feet above the Java Sea and had asked to fly at 38,000 feet to avoid clouds, said Joko Muryo Atmodjo, air transportation director at Indonesia's transport ministry.

Permission was not given at the time due to traffic in the area. Five minutes later, at 6:17 a.m. on Sunday (2317 GMT Saturday), the plane lost contact with air traffic control, Atmodjo said.

Data from Flightradar24.com, which tracks airline flights in real time, showed several nearby aircraft were at altitudes ranging from 34,000 to 36,000 feet at the time, levels that are not unusual for cruising aircraft.