Kalau penerbangan terlambat, kami harus transit lebih lama di bandara lain.

Yes. In this sentence, kalau means if.

• Kalau penerbangan terlambat = If the flight is delayed
• Jika can also mean if

The difference is mainly register:

• kalau = very common in everyday speech
• jika = a bit more formal or written

So this sentence sounds natural and normal in conversation.

Penerbangan means flight, as in the trip/service itself, not the airplane as a physical object.

• penerbangan = flight
• pesawat = airplane / aircraft

So:

• penerbangan terlambat = the flight is delayed
• pesawat terlambat can be understood, but it focuses more on the plane itself and is less precise in this context

If you are talking about airline schedules, connections, or delays, penerbangan is usually the better word.

In Indonesian, adjectives and adjective-like words usually come after the noun they describe.

So:

• penerbangan terlambat = a delayed flight / the flight is delayed
• bandara lain = another airport
• lebih lama = longer

This is a very common pattern in Indonesian:

• noun + description

So penerbangan terlambat is the natural word order.

Terlambat means late or delayed.

In this sentence, it means the flight is delayed:

• penerbangan terlambat = the flight is delayed

Telat usually means the same thing, but:

• terlambat = more standard
• telat = more informal, conversational

So you may hear:

• Kalau penerbangannya telat... in speech

But terlambat is a very good standard choice.

This is an important Indonesian distinction.

• kami = we, but not including the person being spoken to
• kita = we, including the person being spoken to

So kami harus transit... means:

• we have to transit...
• but the listener is not part of that we

If the speaker included the listener in the group, they would say kita harus transit...

English uses just we, so Indonesian is more specific here.

Harus means must, have to, or need to, depending on context.

Here:

• kami harus transit lebih lama = we have to transit longer

A useful thing about Indonesian is that harus does not change for person or number.

So you can say:

• saya harus = I must
• kamu harus = you must
• dia harus = he/she must
• kami harus = we must

No verb conjugation is needed.

Yes, it can be used very naturally as a verb in everyday Indonesian, especially in travel contexts.

So:

• transit di bandara lain = to have a layover / to transit at another airport

This is common and natural.

You might also see longer expressions like:

• singgah
• berhenti sementara
• melakukan transit

But in airline/travel language, just transit is very normal.

Lebih means more, and lama means long or for a long time.

Together:

• lebih lama = longer

So:

• harus transit lebih lama = have to transit longer / have to spend more time in transit

This is the standard way to form a comparative in Indonesian:

• lebih
  • adjective/adverb

Examples:

• lebih cepat = faster
• lebih mahal = more expensive
• lebih lama = longer

Di here is the preposition in / at.

• di bandara = at the airport

Lain means other or another, and it usually comes after the noun:

• bandara lain = another airport / a different airport

So:

• di bandara lain = at another airport

This word order is normal in Indonesian:

• noun + lain

Examples:

• kota lain = another city
• hari lain = another day
• orang lain = another person / other people

No. They look similar, but they are different.

In this sentence:

• di bandara = at the airport
• here di is a preposition, so it is written separately

Compare that with passive verb forms:

• dibuka = opened
• ditulis = written

There, di- is a prefix, so it is written attached to the verb.

A useful rule:

• di
  • place/location → usually separate
    
    • di rumah, di Jakarta, di bandara
• di-
  • verb → attached
    
    • dibaca, dipakai, ditutup

Yes. Indonesian allows both orders.

Original:

• Kalau penerbangan terlambat, kami harus transit lebih lama di bandara lain.

Also natural:

• Kami harus transit lebih lama di bandara lain kalau penerbangan terlambat.

Both mean essentially the same thing:

• If the flight is delayed, we have to transit longer at another airport.

Putting the kalau clause first often makes the condition clearer right away.

Indonesian often does not mark tense the way English does. Time is usually understood from context.

In this sentence, the meaning is clearly conditional/future:

• If the flight is delayed, we have to transit longer...

Even without a word like will, Indonesian speakers understand that this refers to a possible future situation.

If needed, speakers can add time words or markers such as:

• akan = will
• nanti = later
• besok = tomorrow

For example:

• Kalau penerbangan terlambat, kami akan transit lebih lama di bandara lain.

But akan is not necessary here.

The comma separates the conditional clause from the main clause.

• Kalau penerbangan terlambat = the condition
• kami harus transit lebih lama di bandara lain = the result

So the comma works much like in English:

• If the flight is delayed, we have to transit longer at another airport.

In casual writing, people sometimes leave commas out, but using one here is clear and standard.

Yes, absolutely.

• Kalau penerbangan terlambat = If the flight is delayed
• Kalau penerbangannya terlambat = If the flight is delayed

The suffix -nya can make the noun feel more definite, like the in English, depending on context.

So:

• penerbangan = flight / the flight
• penerbangannya = the flight / that flight

Both are natural. The version without -nya is perfectly fine and a bit leaner in style.