“Although he had been drinking”
In my experience in flight, alcohol has been the #1 problem.
If 100 people in the plane, 50 drink, 1 or 2 out of 50 can’t handle their drink and ruin it for the 100.
It's more prevalent in aircraft due to thinner air getting people more drunk faster, but especially when airlines cheap out and don't pressurize the cabin to a low enough altitude.