Nouns ending in -age are usually masculine.
The suffix often marks an action, a result, or a collection.
Is décollage masculine or feminine?
ledécollage
The rule behind it
98.8% of -age nouns are masculine
In context
Le décollage est plus facile que l'atterrissage.
Taking off is easier than landing.
Vous devez attacher vos ceintures pendant le décollage.
You must fasten your seat belts during take-off.
L'avion est prêt pour le décollage.
The plane is ready for take-off.