Learn Hardcore Finnish: Jos vahinko sattuu, soitan päivystykseen heti. - If an accident happens, I call the emergency clinic immediately.

Jos vahinko sattuu, soitan… = If an accident happens, I’ll call… (it might happen, or might not)
Kun vahinko sattuu, soitan… = When the accident happens, I’ll call… (sounds like you’re sure it will happen at some point)

In normal everyday speech here, jos is the natural choice, because accidents are by nature uncertain.

Why is sattuu in the present tense if we’re talking about a possible future accident?

Finnish does not have a separate future tense. The present tense is used both for present and for future time.

So:

Jos vahinko sattuu… literally: If an accident happens…
In context, it naturally means If an accident (ever) happens / If an accident happens (in the future)…

The same is true for soitan: it is present tense but corresponds to English I’ll call here. The future meaning comes from the conditional structure, not from a special verb form.

What does vahinko sattuu literally mean, and why use sattua with vahinko?

Literally, vahinko sattuu is something like “a mishap happens” or “a damage/accident occurs”.

vahinko = a mistake, mishap, damage, something bad that wasn’t intended
sattua = to happen (by chance), to occur; it can also mean to hurt in other contexts (e.g. Käteen sattuu. = My hand hurts.)

In this combination:

Vahinko sattuu ≈ An accident/mishap happens (by chance).

You could also say vahinko tapahtuu (tapahtua = to happen/occur), but vahinko sattuu is very natural and idiomatic, especially for something accidental or unintended.

What is the difference between vahinko, onnettomuus, and tapaturma? They all look like “accident”.

All three can be translated as accident, but they differ in nuance:

vahinko
- very general: a mishap, damage, mistake, accident
- can be small: Lasissa on pieni vahinko. (There’s a small chip/crack in the glass.)
- also used for doing something by mistake: Se oli vahinko. (It was an accident / I didn’t mean to.)
onnettomuus
- a serious accident, often involving people getting hurt: liikenneonnettomuus (traffic accident), junaonnettomuus (train accident)
- more dramatic in feel than vahinko.
tapaturma
- especially a personal injury accident, like at work or at home: työtapaturma (work accident)
- common in official / medical / insurance language.

In Jos vahinko sattuu, soitan päivystykseen heti, vahinko is fairly neutral; context will tell how serious it is.

Why is there no minä before soitan? How do we know it means “I call”?

In Finnish, personal pronouns are usually dropped because the verb ending already shows the person:

soitan = I call (1st person singular)
soitat = you (sg) call
soittaa = he/she/it calls
soitamme = we call, etc.

So soitan by itself clearly means I call or I will call.
You can add the pronoun for emphasis:

Minä soitan päivystykseen heti. = I’ll call the emergency line immediately (as opposed to someone else).

What case is päivystykseen, and what does it add to the meaning of soitan?

Päivystykseen is in the illative case, which often corresponds to “into / to (inside)”.

Nominative: päivystys
Illative singular: päivystykseen = to the emergency duty / emergency clinic / on-call service

With soittaa, the illative -een/-hVn ending often marks the target of a phone call:

Soitan päivystykseen. = I’ll call the emergency duty (service / clinic / line).
Soitan kotiin. = I’ll call home.
Soitan lääkäriin. = I’ll call the doctor (i.e. the doctor’s practice/office).

So päivystykseen answers “where / to which service are you calling?”.

What exactly is päivystys in Finnish healthcare terms?

Päivystys literally relates to being on duty / on call. In healthcare, it usually means:

an emergency department, on-call clinic, or urgent care that is open outside normal hours
or the emergency/on-call service in general.

So soittaa päivystykseen = to call the on-call / emergency service or clinic, typically for urgent medical help or advice.

Why is there a comma after Jos vahinko sattuu? Is it always required?

In Finnish, a comma is normally used between a main clause and a subordinate clause, more consistently than in English.

Jos vahinko sattuu, soitan päivystykseen heti.
- Jos vahinko sattuu = subordinate conditional clause
- soitan päivystykseen heti = main clause

A comma is used between them, regardless of which one comes first. If you reverse the order, you also typically keep the comma:

Soitan päivystykseen heti, jos vahinko sattuu.

So yes, here the comma is standard and expected in normal written Finnish.

Can I change the word order, like Jos sattuu vahinko, soitan heti päivystykseen? Does it change the meaning?

You can change the word order, and the basic meaning stays the same. Word order mainly affects emphasis and rhythm.

All of these are possible:

Jos vahinko sattuu, soitan päivystykseen heti. (neutral)
Jos sattuu vahinko, soitan päivystykseen heti. (slight emphasis on something or other happening, more speech-like)
Jos vahinko sattuu, heti soitan päivystykseen. (emphasis on immediately)

Finnish allows quite a bit of word order flexibility as long as:

the verb is in second position in simple main clauses (here it’s in the second clause), and
the sentence remains clear in context.

Why is it soitan päivystykseen and not something like soitan päivystystä or päivystykselle?

With the meaning “to phone / to call (by phone)”, soittaa usually takes:

allative (-lle) when you emphasise the person you are calling:
- Soitan lääkärille. = I’ll call the doctor (as a person).
illative (-n / -seen / -hVn) when you emphasise the place/service/number you are calling:
- Soitan päivystykseen. = I’ll call the emergency service/clinic.
- Soitan kotiin. = I’ll call home.

Soitan päivystystä wouldn’t work for “call the emergency service”; partitive is used with soittaa in the other meaning to play (an instrument), e.g. soitan pianoa = I play the piano.

What does heti mean, and where can it go in the sentence?

Heti means immediately / right away.

In your sentence:

soitan päivystykseen heti = I’ll call the emergency service immediately.

You can move heti a bit for different emphasis:

Heti soitan päivystykseen. (strong emphasis on immediacy)
Soitan heti päivystykseen. (very natural: I’ll immediately call the emergency service.)

It normally sits close to the verb it modifies.

How would I make this more hypothetical, like “If an accident were to happen, I would call…”?

For a more hypothetical / less likely condition, Finnish uses the conditional mood on both verbs:

Jos vahinko sattuisi, soittaisin päivystykseen heti.
- sattuisi = conditional of sattua
- soittaisin = conditional of soittaa

Nuance:

Jos vahinko sattuu, soitan…
= a realistic, neutral condition (If an accident happens, I’ll call…)
Jos vahinko sattuisi, soittaisin…
= more theoretical or less likely (If an accident were to happen, I would call…).

Could this sentence also mean “If it hurts, I’ll call the emergency service immediately”?

Not in this exact form, because the subject vahinko is clearly “an accident / a mishap”.

For “If it hurts, I’ll call the emergency service immediately”, you would normally say something like:

Jos sattuu, soitan päivystykseen heti. (If it hurts, I’ll call…) – where the subject “it” is just understood from context, or
Jos käteen sattuu, soitan päivystykseen heti. (If my hand hurts, I’ll call…)

So sattua can mean to hurt, but here vahinko makes it clearly “an accident happens”, not “something hurts”.