Η αδερφή μου τσεκάρει πάντα την ώρα της πτήσης πριν πάει στο αεροδρόμιο.

In Modern Greek, the definite article is normally used even when there is a possessive like μου.

So:

• η αδερφή μου = my sister
• ο φίλος μου = my friend
• το σπίτι μας = our house

It does not sound like English the my sister. It is simply the normal Greek pattern.

μου is the unstressed possessive form meaning my, and in standard Greek it usually comes after the noun:

• η αδερφή μου = my sister
• το βιβλίο μου = my book

If you want extra emphasis, Greek often uses δικός:

• η δική μου αδερφή = my own sister / my sister with emphasis

So the word order in the sentence is completely normal.

Yes. τσεκάρω / τσεκάρω is a very common borrowed verb in Modern Greek, especially in informal everyday speech. Here τσεκάρει is 3rd person singular, so it means she checks.

A few forms:

• τσεκάρω / τσεκάρω = I check
• τσεκάρεις = you check
• τσεκάρει = he/she/it checks

It is common and natural in conversation. A more formal or less English-based alternative would be:

• ελέγχει = checks, verifies
• κοιτάζει = looks at, checks

Because the sentence describes a habitual action:

• πάντα = always

So the meaning is not one single future event, but something she regularly does. Greek uses the present tense for habits just like English does in She always checks...

It can move. Greek word order is more flexible than English word order, although some positions sound more neutral than others.

These are all possible:

• Η αδερφή μου τσεκάρει πάντα την ώρα της πτήσης.
• Η αδερφή μου πάντα τσεκάρει την ώρα της πτήσης.

The version in your sentence is very natural. Putting πάντα in different places changes emphasis slightly, but not the basic meaning.

Because ώρα is the direct object of the verb τσεκάρει, so it has to be in the accusative.

The noun changes like this:

• η ώρα = the time/hour (nominative)
• την ώρα = the time/hour (accusative)

So:

• Η αδερφή μου = the subject
• τσεκάρει την ώρα = checks the time

Because this is the genitive, used here to mean of the flight.

So:

• η ώρα της πτήσης = the time of the flight

This is a very common Greek structure: noun + genitive to show possession or relation.

For πτήση:

• η πτήση = the flight
• της πτήσης = of the flight
• την πτήση = the flight (object)

Not exactly. ώρα can mean:

• hour
• time
• time/scheduled time

In this sentence, την ώρα της πτήσης means something like:

• the flight time
• the time of the flight
• the departure time depending on context

So Greek ώρα is broader than the English word hour.

After πριν meaning before, Greek commonly uses a verb in the subjunctive. In everyday Greek, να is often omitted after πριν.

So:

• πριν πάει = before she goes

You may also encounter πριν να πάει, but πριν πάει is very common and natural.

Greek often prefers the perfective form after πριν when talking about a single act or event:

• πριν πάει στο αεροδρόμιο = before she goes to the airport

Using πηγαίνει here would not be the normal choice.

This is connected to aspect, not just tense. Greek distinguishes between:

• πηγαίνει = imperfective, ongoing/habitual
• πάει = perfective form used here in the πριν clause

Even though the whole sentence describes a habit, each individual act of going to the airport is viewed as a complete event, so πάει fits well.

στο is a contraction of:

• σε + το = στο

The preposition σε is very common and can mean to, in, at, or on, depending on context.

Here, because the verb is πάει (goes), στο αεροδρόμιο means:

• to the airport

So:

• πάει στο αεροδρόμιο = she goes to the airport

Yes, both are used and both are correct. The difference is mostly one of style and register:

• αδερφή = very common in everyday Modern Greek
• αδελφή = more formal or more traditional

So η αδερφή μου is a completely natural modern everyday way to say my sister.