Ao desembarcar, Ana percebeu que a mala dela não estava com a bagagem.

Ao desembarcar means when getting off, upon disembarking, or when she landed/got off the plane depending on context.

This structure is:

• ao = a + o
• followed by an infinitive verb: desembarcar

So ao + infinitive often means when doing something, upon doing something, or as soon as someone does something.

Examples:

• Ao chegar, liguei para ela. = When I arrived, I called her.
• Ao abrir a porta, viu o cachorro. = Upon opening the door, he/she saw the dog.

In this sentence, it tells us the moment when Ana noticed the problem.

Both are possible.

• Ao desembarcar = upon disembarking / when disembarking
• Quando desembarcou = when she disembarked

The ao + infinitive structure is very common in Portuguese and often sounds compact and natural, especially in written or narrative style.

So these are similar:

• Ao desembarcar, Ana percebeu...
• Quando desembarcou, Ana percebeu...

The first one is a little more compressed and elegant; the second is more explicit.

The implied subject is Ana.

In sentences like this, the subject of ao + infinitive is usually understood from the main clause. So:

• Ao desembarcar, Ana percebeu...

means:

• When Ana disembarked, Ana noticed...

Portuguese often leaves that subject unstated because it is clear from context.

Percebeu is the preterite, which is used for a completed event in the past.

Here, Ana noticed something at a particular moment:

• she got off the plane
• then she realized the suitcase was missing

So percebeu fits that single completed action.

Percebia would suggest an ongoing, repeated, or background perception, which does not fit as well here.

Compare:

• Ana percebeu o problema. = Ana noticed the problem.
• Ana percebia os problemas com frequência. = Ana used to notice the problems often.

Because estava describes a state or condition in progress at that moment.

The sentence is not focusing on a completed event of the suitcase having been somewhere. It is describing the situation Ana found:

• the suitcase was not with the luggage

So the imperfect estava is natural because it sets the background state.

Compare:

• A mala não estava com a bagagem. = It was not there / it wasn’t with the luggage.
• A mala não esteve com a bagagem sounds much less natural here and would suggest a more bounded, completed state, which is not the point.

A mala dela avoids ambiguity.

In Portuguese, seu/sua can mean:

• his
• her
• your (depending on the variety and context)

So a sua mala could be unclear.

By saying a mala dela, the sentence makes it absolutely clear that the suitcase belongs to her, meaning Ana.

This is very common in Brazilian Portuguese:

• o carro dele = his car
• a bolsa dela = her purse
• a casa deles = their house

Portuguese usually uses definite articles more often than English does.

So:

• a mala dela literally = the suitcase of hers
• natural English translation = her suitcase

Portuguese often prefers:

• o meu livro
• a sua casa
• o carro dele

where English would usually just say:

• my book
• your house
• his car

Mala means suitcase or bag.

Bagagem means baggage/luggage in a broader or collective sense.

So in this sentence:

• a mala dela = her specific suitcase
• a bagagem = the baggage/luggage being transported or collected, probably the rest of the checked luggage

A natural interpretation is that Ana noticed her suitcase was not there with the other bags.

Because bagagem is usually a collective or mass noun, much like luggage in English.

In English, you normally say:

• The luggage is here not
• The luggages are here

Portuguese works similarly:

• A bagagem chegou.
• A bagagem foi extraviada.

So singular bagagem is completely normal, even though it can refer to multiple pieces of baggage.

Here, com a bagagem means something like:

• with the baggage
• among the luggage
• together with the other bags

It does not mean that the suitcase was physically inside another bag. It means it was not there along with the baggage she expected to find.

In an airport context, this likely refers to the luggage at baggage claim.

Because com expresses the idea of together with or alongside the baggage.

• com a bagagem = with the luggage / among the luggage
• na bagagem = in the luggage / inside the baggage

So:

• não estava com a bagagem = it wasn’t there with the other luggage
• não estava na bagagem would suggest being inside a suitcase or inside the baggage, which is not the intended meaning

Que introduces a subordinate clause after the verb perceber.

So:

• Ana percebeu que a mala dela não estava com a bagagem

means:

• Ana noticed that her suitcase was not with the luggage

This is very similar to English that.

Other examples:

• Percebi que ele estava cansado. = I noticed that he was tired.
• Ela viu que a porta estava aberta. = She saw that the door was open.

Yes. Portuguese allows some flexibility.

These are all possible:

• Ao desembarcar, Ana percebeu que a mala dela não estava com a bagagem.
• Ana percebeu, ao desembarcar, que a mala dela não estava com a bagagem.
• Ana percebeu que a mala dela não estava com a bagagem ao desembarcar.

But the first version is the clearest and most natural if you want to set the time first.

Also, the placement of ao desembarcar can slightly affect what it seems to modify, so the original sentence is a good, clean choice.

No. Desembarcar can be used for getting off different kinds of transportation, not just planes.

It can mean:

• get off a plane
• disembark from a ship
• get off a bus or train, depending on context

In airport contexts, it very often means to disembark/land and get off the plane.

So here the most natural interpretation is that Ana got off the plane and then realized her suitcase was missing.