General tendencies when using articles
1) When talking in general about people or things we don’t use the with plural nouns or uncountable nouns.
eg Planes transport people huge distances in short periods of time. (not specific planes but planes in general)
eg Pilots have to do recurrent training every year. (not specific pilots but pilots in general)
2) When talking about jobs or types of things, use a / an with a singular noun to say what job a person has, what group something belongs to or what we use something for.
eg He’s a dispatcher.
eg We have a checklist to remind us of everything we need to check.