yeogwon eobsi bihaenggireul tal su eobseoyo.

없이 means without.

In 여권 없이, it means without a passport.

A simple pattern is:

• noun + 없이 = without + noun

Examples:

• 돈 없이 = without money
• 예약 없이 = without a reservation
• 친구 없이 = without a friend

So 여권 없이 비행기를 탈 수 없어요 literally has the idea of without a passport, (you) cannot board a plane.

Because 없이 attaches directly to a noun phrase and usually does not take 을/를 or 이/가 before it.

So the natural form is:

• 여권 없이 = without a passport

Not:

• 여권을 없이
• 여권이 없이

You can think of 없이 as functioning like a postposition-like word that already completes the phrase.

In 비행기를 탈 수 없어요, 비행기 is the object of 타다.

• 비행기 = airplane
• 비행기를 = airplane + object marker 를

The verb 타다 means to ride / take / board a vehicle, so the vehicle is treated as the object:

• 버스를 타요 = ride/take the bus
• 지하철을 타요 = ride/take the subway
• 비행기를 타요 = take/board a plane

So 를 is there because 비행기 is what you are boarding/riding.

Korean uses 타다 very broadly for getting on and riding many kinds of transportation.

It can mean:

• ride
• take
• board

depending on the context.

Common examples:

• 차를 타다 = ride/take a car
• 버스를 타다 = ride/take a bus
• 기차를 타다 = ride/take a train
• 비행기를 타다 = take/board a plane

So even though ride a plane sounds odd in English, 비행기를 타다 is completely natural in Korean.

This is the grammar pattern -(으)ㄹ 수 없다, which means cannot / be unable to.

Breakdown:

• 타다 = to ride / board
• 탈 = the -(으)ㄹ form attached to the verb stem
• 수 = a way to express possibility/ability
• 없어요 = does not exist / there is not

So:

• 탈 수 있어요 = can ride / can board
• 탈 수 없어요 = cannot ride / cannot board

In this sentence, 비행기를 탈 수 없어요 means cannot board a plane.

The dictionary form is 타다.

To make -(으)ㄹ 수 있다/없다, you use the verb stem plus -(으)ㄹ.

• 타다 → stem 타-
• since the stem ends in a vowel, you add -ㄹ
• 타 + ㄹ → 탈

So:

• 타다 → 탈 수 있어요 / 탈 수 없어요

More examples:

• 가다 → 갈 수 있어요
• 먹다 → 먹을 수 있어요
• 읽다 → 읽을 수 있어요

It most naturally means you cannot board a plane without a passport, and in real life that often implies both:

• it is not permitted
• therefore you are unable to do it

The grammar -(으)ㄹ 수 없어요 often expresses cannot / be unable to. In a context like air travel, that inability usually comes from a rule.

So in English, depending on context, it could feel like:

• You can’t board a plane without a passport
• You’re not allowed to board a plane without a passport

Both match the overall idea.

Korean often leaves out the subject when it is obvious from context.

So 여권 없이 비행기를 탈 수 없어요 can mean things like:

• I can’t board a plane without a passport
• You can’t board a plane without a passport
• People can’t board a plane without a passport

The exact subject depends on the situation.

This is very normal in Korean. You do not need to state the subject every time.

없어요 is in the polite informal style, often called 해요체.

That means it is polite and very commonly used in everyday conversation.

Compare:

• 없어 = casual
• 없어요 = polite
• 없습니다 = formal

So the same sentence can appear as:

• 여권 없이 비행기를 탈 수 없어. = casual
• 여권 없이 비행기를 탈 수 없어요. = polite
• 여권 없이 비행기를 탈 수 없습니다. = formal

Yes. That is also natural, but the nuance is slightly different.

• 여권 없이 비행기를 탈 수 없어요 = You cannot board a plane without a passport
• 여권이 없으면 비행기를 탈 수 없어요 = If you do not have a passport, you cannot board a plane

So:

• 없이 focuses on the without X condition
• -으면 focuses on the if X is absent / if you don’t have X condition

Both are correct and natural.

Yes, in many situations you can.

• 비행기를 탈 수 없어요
• 비행기를 못 타요

Both can mean cannot board the plane.

However, there is a slight nuance:

• -(으)ㄹ 수 없어요 often sounds a bit more explicit about ability/possibility
• 못 + verb is a very common, natural way to say cannot

In this sentence, both are fine, but 탈 수 없어요 can sound a little more formal or explanatory.

For example:

• 여권 없이 비행기를 못 타요. = Without a passport, you can’t board a plane.
• 여권 없이 비행기를 탈 수 없어요. = Without a passport, you cannot board a plane.

Both are natural Korean.