Learn Spanish (Latin America): El vuelo ya había despegado cuando llegamos. - The flight had already taken off when we arrived.

Había despegado is the past perfect tense, which translates to "had taken off". We use it to show that a past action was completely finished before another action in the past. Here, the flight taking off happened first, before the arrival (llegamos).

Why is ya placed before había? Could I say había ya despegado?

In Spanish, you can never separate the helping verb (había) and the past participle (despegado). Because of this strict rule, adverbs like ya (already) or nunca (never) are usually placed right before the helping verb, giving us ya había despegado.

Llegamos is both the present and past tense for "we arrive(d)". How do we know it is the past tense here?

Context is key! The first half of the sentence, ya había despegado, sets the scene firmly in the past. Because the first action is in the past perfect, the interrupting action after cuando (when) must be the preterite past tense meaning "when we arrived".

Does the verb despegar (to take off) have anything to do with pegar (to stick)?