Kuulutus kertoi, että lennolla on pieni viivästys huonon sään takia.

Yes. Finnish often uses kertoa with things like kuulutus (announcement), uutinen (news item), or raportti (report).

So Kuulutus kertoi, että... means something like:

• The announcement said that...
• The announcement stated that...

It sounds normal in Finnish, even though in English we might prefer said or announced rather than told.

Also:

• kuulutus = announcement
• kertoi = told / said / stated

Here kertoi is the past tense of kertoa.

että means that and introduces a subordinate clause.

So the structure is:

• Kuulutus kertoi = The announcement said
• että lennolla on pieni viivästys... = that there is a small delay on the flight...

This is very common in Finnish:

• Hän sanoi, että tulee myöhemmin. = He/She said that he/she will come later.
• Tiedän, että olet väsynyt. = I know that you are tired.

In everyday speech, että is sometimes omitted, but in standard written Finnish it is very common.

Because the announcement happened at a particular moment in the past: it said something.

So:

• kertoo = says / tells
• kertoi = said / told

The speaker is reporting what the announcement said.

This is a normal pattern in Finnish:

• Kuulutus kertoi... = The announcement said...
• Opettaja sanoi... = The teacher said...
• Lehti kirjoitti... = The newspaper wrote...

Lennolla is the adessive form of lento.

• lento = flight
• lennolla = on the flight / during the flight

The ending -lla / -llä often means on, at, or in the context of something.

Here, lennolla does not literally mean sitting physically on top of a flight. It means:

• on the flight
• during the flight
• with this flight

So lennolla on pieni viivästys means literally something like:

• On the flight there is a small delay

which in more natural English becomes:

• The flight has a small delay
• There is a slight delay on the flight

This is because of a stem change called consonant gradation.

The word is:

• lento = flight

But in many inflected forms, nt changes to nn:

• lennon = of the flight
• lennolla = on the flight
• lennolle = onto the flight / for the flight

So the learner does have to get used to the fact that Finnish words often change internally when endings are added.

A few similar examples:

• ranta → rannalla
• katu → kadulla
• matto → matolla

That is basically the literal structure, yes.

Finnish often uses olla (to be) with a location-like phrase to express that something exists somewhere or affects something.

So:

• lennolla on pieni viivästys literally: On the flight is a small delay

This is similar in structure to:

• Pöydällä on kirja. = There is a book on the table.
• Minulla on auto. = I have a car.
  (literally: At me is a car)

So Finnish often expresses having or there being with this kind of structure.

Because Finnish does not always shift tenses in reported speech the way English often does.

English often does this:

• The announcement said that there was a delay.

But Finnish can very naturally say:

• Kuulutus kertoi, että lennolla on pieni viivästys.

This keeps the delay in the present, as something that is still true at the time being discussed.

So:

• kertoi = the announcement happened in the past
• on = the delay is/was current information

If you said oli, that would place the delay more firmly in the past. That could also be possible in some contexts, but on is very natural if the delay is the current content of the announcement.

Because pieni viivästys is the noun phrase functioning as the thing that exists in the sentence: a small delay.

Here it is in the nominative singular:

• pieni = small
• viivästys = delay

Also, the adjective agrees with the noun:

• pieni viivästys
• not pienen viivästys
• not pieni viivästyksen

A useful point: in Finnish existential sentences like this, a singular countable thing is often in the nominative:

• Pöydällä on kirja. = There is a book on the table.
• Lennolla on pieni viivästys. = There is a small delay on the flight.

If it were plural or more indefinite, Finnish often uses the partitive:

• Lennolla on viivästyksiä. = There are delays on the flight / The flight has delays.

Because Finnish has no articles.

So Finnish does not have separate words corresponding directly to English a/an and the.

That means:

• viivästys can mean a delay or the delay
• the exact meaning depends on context

Here pieni viivästys is understood as a small delay or a slight delay.

Context tells you whether something is definite or indefinite.

Because takia is a postposition that requires the genitive.

So:

• huono sää = bad weather
• huonon sään = of bad weather / bad weather’s
• huonon sään takia = because of bad weather

The changes are:

• huono → huonon
• sää → sään

This is the genitive form.

A key thing to remember:

• takia comes after the noun phrase
• and that noun phrase goes into the genitive

Other examples:

• flunssan takia = because of the flu
• kiireen takia = because of hurry
• onnettomuuden takia = because of an accident

Takia means because of.

In this sentence:

• huonon sään takia = because of bad weather

A very close alternative is vuoksi:

• huonon sään vuoksi

Both mean almost the same thing, and both take the genitive before them.

A rough difference:

• takia = very common, neutral, everyday
• vuoksi = often a bit more formal or written

So this sentence could also be written as:

• Kuulutus kertoi, että lennolla on pieni viivästys huonon sään vuoksi.

The given word order is very natural, but Finnish word order is more flexible than English word order.

Default structure here:

• Kuulutus kertoi, että lennolla on pieni viivästys huonon sään takia.

Inside the subordinate clause, this order is natural because it presents:

1. the setting: lennolla
2. the verb: on
3. the new information: pieni viivästys
4. the reason: huonon sään takia

You could move parts around for emphasis, for example:

• Kuulutus kertoi, että huonon sään takia lennolla on pieni viivästys.

This puts more focus on the reason first.

So the original order is not the only possible order, but it is a very normal and neutral one.

Literally it is small delay, but in natural English we usually say:

• a slight delay
• a minor delay
• a small delay

So pieni is doing the same job here as slight/minor often does in English.

This is common in Finnish: pieni can be used in places where English might choose a less literal adjective.

For example:

• pieni ongelma = a small problem / a minor problem
• pieni tauko = a short break / a little break
• pieni viivästys = a slight delay

Yes. This sentence is perfectly good Finnish, but there are other natural ways to say similar things.

For example:

• Kuulutuksessa sanottiin, että lento on vähän myöhässä huonon sään takia. = The announcement said that the flight is a little late because of bad weather.

• Lento viivästyy hieman huonon sään takia. = The flight is delayed slightly because of bad weather.

The original sentence is a bit more formal/informational in tone, which fits an announcement very well.