The Far Eastern Air Force quickly dominated the skies over Korea, T. R. Fehrenbach explains (in This Kind of War):
Unprepared for tactical ground-support missions, FEAF at first did almost as much harm as good, shooting up American positions and dealing grievous harm to friendly ROK units on the roads, but these mistakes were quickly corrected.
After gaining air control, FEAF began to interdict the ever-lengthening supply lines of the NKPA, throttling a great deal of its resupply to the front. But air over a country like Korea could never be in itself decisive. The country was too broken, and the NKPA was never completely road bound. Its units and its supplies, often on foot, went through the valleys and over the ridges, and too much of them arrived at the front. The NKPA did not amass the great, vulnerable mountains of matériel common to Western armies, because in the main it did not have them.
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It is expensive to use aircraft in place of artillery — but in 1950 the United States had more aircraft, relatively, than cannon in the Far East.
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All through the Korean War, whenever the enemy came out into the open, he was subject to immediate, effective air attack.
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The NKPA became very good at camouflage and at night movement.
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Based in Japan, which never changed from peacetime ways, many of them had wives and family stationed at their fields. Many a pilot flew out in the predawn darkness to strafe and rocket enemy troops all day across the burning hills of Korea, then returned to play cards with his wife at night.
This was harder on both pilots and family than if the dependents had been an ocean away.