Nous voyageons en avion.

Because voyageons is the conjugated form of the verb voyager in the present tense for nous (we).

• voyager = the infinitive, to travel
• nous voyageons = we travel / we are traveling

For regular -er verbs, the nous form in the present usually ends in -ons:

• nous parlons = we speak
• nous regardons = we watch
• nous voyageons = we travel

That extra e is there to keep the g sound soft.

In French:

• g before a, o, u usually sounds hard, like in go
• g before e, i usually sounds soft, like the s in measure

Without the extra e, voyagons would suggest a hard g sound, which is wrong. So French writes voyageons to keep the soft sound.

The same thing happens in other verbs:

• manger → nous mangeons
• nager → nous nageons

It is the present tense.

In French, the present tense can mean different things depending on context:

• we travel
• we are traveling
• sometimes even we do travel

So Nous voyageons en avion can describe:

• a general habit: We travel by plane
• what is happening now: We are traveling by plane

Because with many means of transport, French uses en where English uses by.

So:

• en avion = by plane
• en train = by train
• en voiture = by car

This is one of those places where you should not translate word-for-word. Even though en often means in, here the expression en + transport means by means of that transport.

Because in French, when talking about a means of transport, en is usually followed directly by the noun, without un, le, or l’.

So you say:

• en avion
• en train
• en voiture

Not:

• en un avion
• en l’avion
  unless you mean something very specific and unusual.

This is just the normal pattern for many vehicles.

Yes, but they are not used in exactly the same way.

• en avion = the usual way to say by plane
• par avion = also possible, but often feels more like by air or is common in contexts like shipping/mail
• dans un avion = in a plane, focusing on being physically inside the plane

So for the sentence here, en avion is the most natural choice.

Examples:

• Nous voyageons en avion. = We travel by plane.
• Le colis part par avion. = The package goes by air.
• Nous sommes dans un avion. = We are in a plane.

Both can relate to movement, but they are not the same.

• voyager = to travel
• aller = to go

voyager talks about traveling in a general sense, often the activity itself. aller usually focuses more on going somewhere specific.

Compare:

• Nous voyageons en avion. = We travel by plane.
• Nous allons à Paris en avion. = We are going to Paris by plane.

So voyager is about the act or habit of traveling, while aller is often about destination.

Both are correct, but in everyday spoken French, people very often use on instead of nous.

So in conversation, you might hear:

• On voyage en avion.

That can mean:

• We travel by plane

But nous is still completely correct and common in:

• writing
• formal speech
• careful or standard French

So Nous voyageons en avion is perfectly good French, just a bit more formal or textbook-style than On voyage en avion.

A rough pronunciation is:

noo vwa-ya-zhon ahn na-vyon

A few helpful points:

• nous sounds like noo
• voyageons has a soft zh sound, like the s in measure
• the final -ons is nasal; you do not pronounce a clear s
• avion sounds roughly like a-vyon
• en is nasal too

So the sentence flows roughly as:

noo vwa-ya-zhon ahn na-vyon