Learn Hardcore Korean: bihaengi jiyeondwaeseo gonghangeseo gidaryeoyo. - The flight is delayed, so I’m waiting at the airport.

지연돼서 comes from the passive verb 지연되다 (“to be delayed”). It’s formed by attaching the connective -아서/어서 to the stem 지연돼-, so literally it means “because (it) was delayed.”

What is the function of -서 in 지연돼서?

In Korean, -서 (from -아서/어서) links two clauses by expressing cause or reason. Here, 지연돼서 gives the reason (“because the flight was delayed”) for the action in the main clause.

Why is it 돼서 instead of 되어서?

돼서 is the contracted, more natural form of 되어서. Both are grammatically correct, but 돼서 is far more common in everyday spoken and written Korean.

What’s the difference between 지연되다 and 연착되다?

Both mean “to be delayed,” but:

연착되다 originally refers to trains or flights arriving/departing late and sounds a bit more colloquial.
지연되다 is slightly more formal or written-style and used in announcements or official contexts.

Why is 비행 followed by the particle 이, and could 는 or 가 be used instead?

이 is the subject marker attached when a noun ends in a consonant (here 비행 ends in ㅇ).
You could use 가 if the noun ended in a vowel.
Using 는 (the topic marker) is also possible (비행은 지연돼서…) but that shifts the focus: it suggests contrast or emphasis on “the flight” as a topic rather than simply marking it as the new subject.

Why do we say 공항에서 instead of 공항에?

에서 marks the location where an action takes place (“waiting at the airport”).
에 alone would indicate destination or existence (“arrive at” or “be at”), so 공항에 기다려요 would sound unnatural for “waiting.”

Why is the main verb 기다려요 in the simple present, and how would the progressive form change the nuance?

기다려요 is the polite present tense, which in Korean often implies an ongoing state (“I wait”).
If you use 기다리고 있어요 (“I am waiting”), you emphasize the ongoing, moment-by-moment action a bit more, but both are natural.

What politeness level is expressed by -아요 in 기다려요, and what other endings could you use?

-아요/어요 is polite informal (or “standard polite”). Other common endings:

-습니다 (formal polite) → 기다립니다
-아/어 (casual) → 기다려 (with friends or younger people)
-십니다 (very formal/honorific) for announcements.

Can you omit 공항에서 or 비행이 in casual conversation, and how would that affect the meaning?

Yes. Korean often drops contextually clear elements:

지연돼서 기다려요 (omitting 공항에서) still means “(Because of the delay,) I’m waiting,” but you lose the specific location.
지연돼서 공항에서 (omitting 기다려요) sounds incomplete; the verb is needed.
공항에서 기다려요 (omitting 비행이 지연돼서) just says “I’m waiting at the airport” without giving the reason.