I often see writers use the term “aircrafts” when referring to two or more aircraft. “Aircraft” is the correct term for both singular and plural cases.
Example the first: “The aircraft flew until it ran out of fuel. Then it made a sudden landing.”
Example the second: “The aircraft were parked wingtip to wingtip making them easy targets for strafing by treacherous seagulls.
It’s one of those wonderfully wacky word usages that make English so much fun 🙂