Vor dem Abflug kontrolliere ich die Flugnummer.

German often puts a time expression at the beginning of the sentence to set the scene first.

• Vor dem Abflug = before departure
• Then comes the conjugated verb: kontrolliere
• Then the subject: ich

This follows the normal German verb-second rule:

• Vor dem Abflug kontrolliere ich die Flugnummer.
• Ich kontrolliere vor dem Abflug die Flugnummer.

Both are correct. The version with Vor dem Abflug first gives a little more emphasis to the time.

Because in a main clause, German puts the finite verb in the second position.

Here, the first position is already taken by Vor dem Abflug, so the verb must come next:

• 1st position: Vor dem Abflug
• 2nd position: kontrolliere
• then subject: ich

This is a very common German word order pattern.

The preposition vor takes the dative case when it refers to time, as it does here.

So:

• der Abflug = the departure
• dative singular becomes dem Abflug

That is why you get:

• vor dem Abflug = before departure

Here vor means before in a time sense.

German vor can be used in different ways:

• vor dem Haus = in front of the house
• vor dem Abflug = before departure

So the meaning depends on context. In this sentence, it is clearly about time.

Kontrolliere is the 1st person singular present tense of kontrollieren.

The verb is:

• kontrollieren = to check / inspect / verify

Present tense:

• ich kontrolliere
• du kontrollierst
• er/sie/es kontrolliert
• wir kontrollieren
• ihr kontrolliert
• sie/Sie kontrollieren

So kontrolliere ich means I check.

No. This is an important false friend.

In this sentence, kontrollieren means:

• to check
• to inspect
• to verify

It usually does not mean English to control in the sense of to be in charge of.

So:

• Ich kontrolliere die Flugnummer = I check the flight number

not

• I control the flight number

Die Flugnummer is the direct object of the verb, so it is in the accusative case.

The noun is:

• die Flugnummer = the flight number

It is feminine, so:

• nominative: die Flugnummer
• accusative: die Flugnummer

For feminine nouns, nominative and accusative singular look the same, so the article stays die.

German often forms compound nouns by joining words together.

• Flug = flight
• Nummer = number
• Flugnummer = flight number

This is extremely common in German. English often uses separate words where German uses one compound noun.

Also, the gender of a compound noun usually comes from the final part. Since Nummer is feminine (die Nummer), die Flugnummer is also feminine.

Abflug means departure, especially for a plane or flight.

It comes from:

• ab- = away / off
• Flug = flight

So it is a very natural airport/travel word.

Examples:

• der Abflug = the departure
• die Abflugzeit = departure time
• der Abflugterminal = departure terminal

Yes, absolutely.

This version is also correct:

• Ich kontrolliere die Flugnummer vor dem Abflug.

The difference is mainly emphasis:

• Vor dem Abflug kontrolliere ich die Flugnummer.
  Emphasizes the time expression first.
• Ich kontrolliere die Flugnummer vor dem Abflug.
  Starts more neutrally with the subject.

Both are normal German.

Because in German, all nouns are capitalized.

So in this sentence:

• Abflug is a noun
• Flugnummer is a noun

That is why they begin with capital letters.

This is a basic but very important spelling rule in German.

No. The sentence already has the definite article:

• die Flugnummer = the flight number

German uses articles very regularly, often more regularly than English. Here die clearly shows that it means the flight number.

If you wanted to say my flight number, you would say:

• meine Flugnummer

So the sentence could become:

• Vor dem Abflug kontrolliere ich meine Flugnummer.

Not usually in this sentence. Abflug is better understood as departure.

English takeoff focuses on the physical moment the plane leaves the ground.
German Abflug in travel contexts often refers more broadly to the scheduled departure of a flight.

So before departure is the safer translation here.