Why does Zelenskyy urge NATO to impose a no-fly zone? [duplicate]

Ukraine's president, Volodymyr Zelenskyy, asked again on last Monday for a no-fly zone. Based on this article from The Guardian:

So far the war in Ukraine has not depended heavily on air power, on
either side. In its invasion Russia has relied mostly on long-range
missiles and surface artillery fire to attack Ukrainian targets.

So what is the reason behind Zelenskyy's insisting on imposing a no-fly zone if the war is largely based on missiles?

Edited

The question closed as duplicate of this question. These are not the same. My question is about cause of Zelenskyy's insisting on imposing no-fly zone. But the question that is considered to be same to my question is about how NATO can impose no-fly zone while it explicitly stated to not send any troop to Ukraine.

I am wondering about how could setting up such a no-fly zone actually
be implemented in the current context. The announcement would be the
easy part, but it is not clear how could NATO actually enforce it
since it explicitly stated to not send any NATO troops to Ukraine.