An aircraftman is a very low rank in the British air force (the RAF), and also a person who holds that rank. It is the first step, like a private in the army — not an officer, and not a special job title. The word looks as if it should mean “a man who works on aircraft,” but that is not how it is used: a mechanic who fixes planes is not an aircraftman just by doing that work. You meet it in British news, war stories, and RAF talk. American English almost never uses it; the US air force says airman instead. It feels official and military. There is a step just above it, leading aircraftman, which is still not an officer. Older British use also had aircraftwoman for women; the rank-word you have here is the old male form, and people still use it as the name of the rank itself.

英國皇家空軍士兵（最低階級；美國說 airman）