Imparfait vs. Passé composé

Bonjour Wyn Ron !

Aaah the eternal question ;)
Knowing when to use L'Imparfait versus Le Passé Composé can indeed be complicated for learners, so here are some guidelines:

-> Imparfait is used to express:
- a habit in the past = used to
- a continuous action in the past = was doing
- to describe a past state or situation = it was
- after "si" in hypothetical statements = if I had

-> Passé Composé is used to express:
- a past action with a clear beginning and end in the past = did
- a brief action in the past

Here are links to our related lessons for more examples :
https://progress.lawlessfrench.com/revision/grammar/l-imparfait-usage-expressing-continuing-action-in-the-past-imperfect-tense
https://progress.lawlessfrench.com/revision/grammar/l-imparfait-usage-expressing-habits-or-repeated-actions-in-the-past-imperfect-tense
https://progress.lawlessfrench.com/revision/grammar/l-imparfait-usage-describing-and-expressing-opinions-in-the-past-imperfect-tense
https://progress.lawlessfrench.com/revision/grammar/l-imparfait-usage-in-hypothetical-clauses-introduced-by-si-if-followed-by-le-conditionnel-present
and
https://progress.lawlessfrench.com/revision/grammar/le-passe-compose-usage-on-its-own-or-with-l-imparfait

I hope that's helpful!
À bientôt !

Bonjour Aurelie, merci de votre aide. For example, I want to say the airplane was on time, when I am in conversation with a friend whom asked me "how was your vacation?". Do I say? Le vol était à l'heure (this described the situation) or Le vol a été à l'heure (this action had a beginning and an end in the past) Wyn

Bonjour Wyn Ron ! In that case, it's a description, so you will use L'Imparfait :) Bonne journée !