航 (háng) is a bound morpheme meaning "to navigate," "to sail," or "to fly." It does not typically stand alone but forms many important compound words related to transportation, such as 航空 (aviation), 航线 (route), and 航班 (flight).
这家航空公司开通了好几条国际航线。
Zhè jiā hángkōng gōngsī kāitōng le hǎo jǐ tiáo guójì hángxiàn.
This airline has opened several international routes.
航班因为天气原因取消了。
Hángbān yīnwèi tiānqì yuányīn qǔxiāo le.
The flight was canceled due to weather.
他在航天领域工作了二十多年。
Tā zài hángtiān lǐngyù gōngzuò le èrshí duō nián.
He has worked in the aerospace field for over twenty years.