This is the 1030th most frequent Turkish word.
uçağı
"Uçağı" means "the plane" or "the airplane" in English.
The word 'uçağı' here is the accusative form of 'uçak' (airplane) because it is the direct object of the verb 'görmek' (to see).
Uçağı havada görmek beni çok heyecanlandırıyor.
Seeing the airplane in the sky excites me a lot.
In this example, 'uçağı' is also in the accusative form, used to indicate the airplane is the entity being directed.
Uçağı terminale doğru yönlendiriyorlar.
They are directing the airplane towards the terminal.
Here, 'uçağı' is in the accusative case and is the object of the action described by 'boyarken' (while painting).