What would be considered a Level 3 fault in a ship? Just curious

[UnionPacific1983WP]

In the Engineer's Report, I notice there's 3 levels of fault: Level 1, just info. Level 2, something you might want to check out, and Level 3, from its icon, I would assume it to be a deadly fault. What would be considered a Level 3 fault? I've noticed that not having a parachute is only considered Level 2, so I don't know what a L3 would be. Just curious.

[Norcalplanner]

Hatch is obstructed and can't be opened.

[Alshain]

No control is Level 3.