Yes, you can say 비행기의 비, but in practice there are a few different ways. 1. 날 비 ("to fly" 비). This is the traditional and more formal way to refer to hanja characters with their meaning. The fist part explains the meaning (usually) in native Korean (>날 is the future/indefinite form of 날다 = to fly), and the second part shows the pronunciation. Other examples: 하늘 천 ("sky" 천(天)), 갈 거("to go" 거(去)), etc. 2. 비행기(의) 비, or '비행기'라고 할 때(의) 비 (비 as when you say 비행기) This just tells what one means by giving an example. In everyday situation, this is probably more common. e.g. A: 이름이 영철이야? 한자로 무슨 영이야? B: 응, '영웅' 할 때 '영' 자야 [or 응, 영웅 '영' 자].