Usage patterns
〈事〉の際にon the occasion of ~; at the time of ~
In the event of a fire, please use the emergency exit.
〈場所〉の際に立つto stand right at the edge of a place
I stood right at the edge of the cliff and looked at the view.
〈動詞〉際にwhen doing ~; at the moment of ~
When you depart, please check that you haven't forgotten anything.
この際at this point; now that things stand this way
Since we're at it, let me say it clearly.
Expressions
いまわの際verge of death; dying moments 際どいところclose call; narrow margin; the eleventh hour