domestic flight; domestic airline
Refers to domestic air routes or the airlines that operate them. Often used in contrast with 国際線 (international flights).
国内線の搭乗手続きはあちらです。
Check-in for domestic flights is over there.
その航空会社は国内線を大幅に増やした。
That airline significantly increased its domestic routes.
I boarded a domestic flight from Haneda and went to Osaka.
The domestic flight terminal is in Building No. 1.
The domestic flight to Fukuoka departs from Gate 3.