This is the 2876th most frequent Polish word.
lotniczych
"Lotniczych" means "aviation" or "related to aviation" in English.
Adjective here is describing the noun 'zakładach' referring to facilities related to aviation.
Pracuję w zakładach lotniczych.
I work in an aerospace plant.
Adjective here modifies 'maszyn', referring to devices related to aviation.
W muzeum zobaczyłem wystawę maszyn lotniczych.
At the museum, I saw an exhibit of aviation machines.
Used as an adjective to describe 'maszyn', connected to machines pertaining to aviation.