- What time does the plane arrive tomorrow?
- Where the plane arrives?
Or one of this sentences is incorrect? (I'm not english-speaking person).
Where the plane arrives? is incorrect: as a question this also requires subject-auxiliary-inversion. You want to say
Where does the plane arrive?
However, where the plane arrives is acceptable as a subordinate relative clause; this does not employ subject-auxiliary inversion:
Gate 17, where the plane arrives, is on the West Concourse.
Where the plane arrives will depend on the weather.
I don't know where the plane arrives
ADDED:
Edwin Ashworth points out that a relative like Where the plane arrives may actually act as either a canonical question or a declarative question in a context where it is understood as a fragment—the remainder of a full sentence from which readily inferrable matter has been omitted as superfluous:
CANONICAL QUESTION:
A: Go right on down to Gate 17.
B:Is thatwhere the plane arrives?DECLARATIVE QUESTION:
A: Go right on down to Gate 17.
B:And that iswhere the plane arrives?
Note however that neither of these expressly asks the hearer to name the location, as Where does the plane arrive? does—they ask the hearer to confirm or deny your understanding that the plane arrives at Gate 17.