Learn Hardcore Czech: Na letišti se budu ptát, kde je autobus, který jede do centra. - At the airport I will ask where the bus that goes to the center is.

na letišti = literally “on the airport,” but idiomatically “at the airport.”
Many public places use na:
- na nádraží (at the station)
- na poště (at the post office)
- na univerzitě (at the university)

v letišti would sound like you are physically inside the structure of the airport building, not just “at the airport” in general. For the normal “at the airport” meaning, Czechs say na letišti.

What is the ending -i in letišti? Which case is that?

Letišti is the locative singular of letiště (neuter noun, “airport”).

Nominative: letiště (the airport)
Locative: (o) letišti, na letišti (at the airport)

The locative case is used mainly after certain prepositions like v, na, o, po when we talk about location:

v městě (in the city)
na stole (on the table)
na letišti (at the airport)

Why do we need se in se budu ptát?

Because ptát se is a reflexive verb in Czech; its dictionary form is ptát se = “to ask (a question / about something).”

Without se, ptát usually means “to torment / to torture,” which is a different verb.
So the reflexive se is an essential part of the verb ptát se, not just an optional pronoun.

Think of ptát se as one unit, like learning “to ask” as a fixed phrase rather than just “ptát” alone.

Where does se go in this sentence? Can I say Na letišti budu se ptát?

In modern Czech, Na letišti se budu ptát is the natural word order. Se is a clitic (an unstressed short word) and tends to stand early in the clause, usually after the first stressed element.

Very natural: Na letišti se budu ptát…
Also possible in some contexts: Budu se ptát na letišti…
Na letišti budu se ptát… sounds unusual and slightly wrong to native speakers.

A good basic rule: keep se close to the verb, but don’t push it too far back in the sentence; it usually comes early.

How is the future tense formed in se budu ptát? Why not something like se ptám budu?

Czech forms one type of future with budu + infinitive for imperfective verbs:

ptát se (to ask, imperfective) → budu se ptát = I will be asking / I will ask (in general)

The pattern is:

budu / budeš / bude / budeme / budete / budou
- infinitive
  e.g. budu číst, bude psát, budeme pracovat, budu se ptát

You cannot say se ptám budu; that mixes present and future wrongly. The auxiliary budu must come before the infinitive: budu (se) ptát.

What is the difference between budu se ptát and zeptám se?

Both can be translated as “I will ask”, but they differ in aspect:

budu se ptát – imperfective future
- Focus on the process or repeated act: “I’ll be asking / I’ll be (going around) asking.”
- Can suggest a longer or less single, finished action.
zeptám se – perfective future (from zeptat se)
- Focus on a single, completed act: “I will (once) ask,” “I’ll ask (and that’s it).”

In your sentence, Na letišti se budu ptát, kde je autobus…, it can imply you might ask several people or that asking is part of a process. If you said Na letišti se zeptám, kde je autobus…, it sounds more like one quick question.

Why is there a comma before kde in … se budu ptát, kde je autobus …?

Czech uses a comma to separate a main clause from a subordinate clause introduced by words like kde, že, protože, etc.

Main clause: Na letišti se budu ptát
Subordinate clause: kde je autobus…

So you put a comma before kde to mark the beginning of the subordinate (indirect question) clause:

Budu se ptát, kde je autobus.
Nevím, kde je autobus.

In kde je autobus, why does it look like normal question word order if it’s an indirect question?

In Czech, indirect questions keep the same word order as direct questions starting with a question word.

Direct: Kde je autobus? (Where is the bus?)
Indirect: Ptám se, kde je autobus. (I’m asking where the bus is.)

Czech does not switch to “where the bus is” order like English; it simply embeds the question as it is:

Direct: Kdy přijede vlak?
Indirect: Nevím, kdy přijede vlak.

Could we say kde autobus je instead of kde je autobus?

Kde je autobus is the normal, neutral word order.

Kde autobus je is possible but more marked; it can sound a bit emphatic, like stressing autobus versus something else, e.g.:

Kde autobus je, ale vlak ne? – “Where the bus is, but not the train?”

In your sentence, for a neutral meaning, you should use kde je autobus.

Why is it autobus, který jede do centra and not které or která?

The relative pronoun který agrees with the noun autobus in gender, number, and case.

autobus is masculine inanimate, singular, nominative.
So the correct form is který (masculine singular nominative).

Other forms, for comparison:

Masculine: který
Feminine: která (e.g. žena, která…)
Neuter: které (e.g. město, které…)

So: autobus, který jede do centra = “the bus that is going to the centre.”

Could we just say autobus do centra instead of autobus, který jede do centra?

Yes, in many contexts you can say:

Na letišti se budu ptát, kde je autobus do centra.

This is very natural and actually shorter; Czechs often say autobus do centra, vlak do Brna, etc.

Difference in nuance:

autobus do centra – more compact, like a label (“the bus to the centre”).
autobus, který jede do centra – more explicit description (“the bus that goes to the centre”).

Both are correct; the relative clause version is just more “sentence-like” and explanatory.

Why is it do centra and not do centrumu or do centrum?

The preposition do (“to, into”) always takes the genitive case.

Nominative: centrum (centre)
Genitive singular: centra

So:

do centra = “to the centre”

You cannot say do centrum (that’s nominative/accusative form, wrong case here).
centrumu would be another genitive form used mostly for some masculine patterns; centrum here is a neuter noun of the -um type, and its genitive is centra.

Why is jede in the present tense if in English we say “goes to the centre” or “is going to the centre” (often with future meaning)?

Czech present tense of motion verbs like jet / jít can describe:

Current action
- Autobus jede do centra. – The bus is going to the centre (right now).
Timetabled / regular action, which often has a future sense in English:
- Autobus jede v šest hodin. – The bus goes / leaves at six (future timetable).

In autobus, který jede do centra, we are describing the kind of bus (the one that goes to the centre), not focusing on the exact time, so present jede is natural and matches both “goes” and “is going” in English.