Learn Turkish: Uçağın doğru koordinatı bildirmesi zorunlu. - The airplane's reporting the correct coordinate is mandatory.

When an entire action acts as the subject of a sentence, we turn it into a noun clause. The 'doer' of that embedded action takes the genitive case suffix, much like an English possessive. Here, the action of reporting belongs to the airplane, so uçak takes the genitive suffix -ın (and the final k softens to ğ) to become uçağın.

Why does the verb bildirmek (to report) take the -me suffix here instead of -dik?

The -me suffix creates a verbal noun for the general idea, concept, or obligation of an action. We use -me here because the reporting is an action that is required to happen, not a stated fact that has already happened or is currently happening (which would require -dik).

Why is koordinat (coordinate) in the accusative case (koordinatı)?

Even though the verb bildirmek has been turned into a noun (bildirmesi), it still acts like a verb toward its own objects. Because the airplane is reporting a specific, definite thing ('the correct coordinate'), koordinat takes the definite accusative suffix -ı.

Why isn't there a verb like 'is' at the end of the sentence?