Pilotfag
There was no storm during his flight as far as I recall.
I was working as a flight instructor when John Jr. crashed.
All of us, instructors, were theorizing about what happened.
We concluded that he lost reference with the horizon due to low visibility and due to his inexperience lost control, stalled and spun or just flew into the water. CFIT-controlled flight into terrain.
<It was a nasty night. Conditions at Martha's Vineyard were reported as clear with visibility of eight miles, but erratic: a few minutes earlier they had been humid and hazy with only six miles visibility. Kennedy's newly acquired certificate for flying his plane using instruments alone forbade him to fly with visibility less than five miles.
https://www.theguardian.com/world/1999/jul/25/kennedy.usa