noun
rescue helicopter
A helicopter used for search and rescue operations, often by the coast guard, military, or disaster response teams.
遭難者を救難ヘリコプターで救助した。
They rescued the victims with a rescue helicopter.
救助ヘリ is a more casual abbreviation often used in news or conversation, while 救難ヘリコプター is the full formal term.
Compound of 救難 (rescue, relief) and ヘリコプター (helicopter).