Flyselskabet har et erstatningsfly, i tilfælde af at forbindelsesflyet ikke kommer.

Danish very often combines nouns into a single compound word.

• fly = plane / flight
• selskab = company
• flyselskab = airline
• flyselskabet = the airline

The ending -et is the definite ending for a neuter noun, so instead of using a separate word like the, Danish usually adds the definiteness to the noun itself.

So:

• et flyselskab = an airline
• flyselskabet = the airline

Because fly is a neuter noun in Danish, and neuter nouns take et in the singular indefinite form.

So:

• et fly = a plane
• et erstatningsfly = a replacement plane

A good rule of thumb is that the last part of a compound usually determines the gender. Since the last part is fly, the whole compound takes et.

Literally, it is something like replacement-plane.

It is made from:

• erstatning = replacement
• fly = plane

So et erstatningsfly is a plane used as a substitute if the original or expected one does not arrive or cannot be used.

This kind of compound is very normal in Danish. English often uses two words where Danish prefers one.

That -s- is a very common linking element in Danish compounds. It does not have a separate meaning of its own; it just helps connect the parts of the compound.

For example:

• erstatning
  • fly → erstatningsfly
• forbindelse
  • fly → forbindelsesfly

You do not translate that -s- directly. It is just part of how many Danish compound nouns are formed.

Again, this is a compound noun.

• forbindelse = connection
• fly = plane / flight
• forbindelsesfly = connecting flight / connection flight
• forbindelsesflyet = the connecting flight

The ending -et makes it definite: the connecting flight.

In travel contexts, Danish fly can refer to the aircraft itself or to the flight, depending on context. Here, English would usually say the connecting flight, even though the Danish word contains fly.

Because the sentence is talking about specific, identifiable things:

• Flyselskabet = the airline
• forbindelsesflyet = the connecting flight

Danish often uses the definite form when the listener is expected to know which thing is meant from the situation or context. That is very similar to English using the.

So the sentence is not talking about just any airline or any connecting flight, but about the airline involved and the relevant connecting flight.

Yes, you often could say hvis here, and it would sound natural:

• ... hvis forbindelsesflyet ikke kommer = ... if the connecting flight doesn’t come/arrive

But i tilfælde af at is a bit more formal and more like:

• in case
• in the event that

So the original sentence sounds slightly more formal or official. It fits well in written information, announcements, policies, or customer service language.

Because i tilfælde af is a fixed expression meaning in case of or in the event of, and when it is followed by a full clause, Danish adds at.

Compare these:

• i tilfælde af forsinkelse = in case of delay

  • here, forsinkelse is a noun

• i tilfælde af at flyet er forsinket = in case the plane is delayed

  • here, flyet er forsinket is a clause

So af belongs to the expression i tilfælde af, and at introduces the clause that follows.

Because this is a subordinate clause:

• ... at forbindelsesflyet ikke kommer

In Danish subordinate clauses, the finite verb usually comes after sentence adverbs like ikke.

So:

• Main clause: Flyet kommer ikke = The plane is not coming
• Subordinate clause: ... at flyet ikke kommer = ... that the plane is not coming

This is one of the most important word-order differences in Danish.

A simple way to remember it:

• main clause: verb before ikke
• subordinate clause: ikke before the verb

In Danish, komme is very commonly used for vehicles, transport, and arrivals in general. So flyet kommer can naturally mean:

• the plane arrives
• the flight comes in
• the flight shows up

English usually prefers arrive in this context, but Danish often uses komme where English would not.

So although kommer literally looks like comes, the natural English meaning here is usually arrives.

Yes. Danish often uses the present tense for future situations, especially when the future event is understood from context.

So:

• Flyselskabet har et erstatningsfly does not necessarily mean only right now; it can mean the airline has / keeps / provides a replacement plane as a standing arrangement.
• ... hvis forbindelsesflyet ikke kommer refers to a possible future event.

This is very normal in Danish and works a lot like English in sentences such as:

• If the train doesn’t come, we take a taxi.

Present tense, but future meaning.

Yes. A more everyday version might be:

• Flyselskabet har et erstatningsfly, hvis forbindelsesflyet ikke kommer.

Or even:

• Hvis forbindelsesflyet ikke kommer, har flyselskabet et erstatningsfly.

These mean basically the same thing, but i tilfælde af at sounds more formal and official than hvis.

So the original sentence is correct and natural, but it has a slightly more formal tone than ordinary conversation.