on the occasion of
at the time of
Structure
- Noun + に際し / に際して
- Verb[る] + に際し / に際して
- Noun + に際しての + Noun
硬
[Extremely formal・Used in instructions, warnings, speeches, etc.・に際しまして form is also used, mostly in speech]
[Similar to にあたって, に際して usually has to do with some sort of preparation for a future event]