Because with air force, critical asset is both people and planes. Just planes is not enough. You can't train pilots not having planes yes, but when you got planes, hard part starts, not ends. It will take many years to have prepared Ukrainian pilots to go into hostile airspace SEAD missions. No one except USAF can do it today. It requires very complex collaboration of many different assets in a manner that is incredibly lengthy and expensive to train for. This is why America leads in it: it has time, space, and cash. There's no way to shortcut it. This is also why Russia concentrates on ground-based SAMs and it's air force is shit: because training SAM operators is cheap and quick. They provide good defence. Ukraine has the same, for same reason. So they are stuck hitting each other with drones because none can do an air offensive.

This does not answer the question, though.

In light of my answer, only way it can help is direct participation with their own units, not just supplying equipment. This is a line West is not ready to cross. Especially since it will only have considerable effect if Westnern planes with Western crews operate over internationally recognised Russian territory (over Ukraine-controlled territory Ukrainian air force dominates as it is, over occupied territory, there are few military significant assets). It means going from a proxy war to a real war.

> over occupied territory, there are few military significant assets

Are you sure about that? I'd say that the war could be ended rather quickly if Russians were attacked the moment they set foot on Ukrainian land. Also, an air force could destroy supply lines going deep into Ukraine.

Because of politics.

This war has been nothing but a blessing to the West. Putin's forces and weapons have been very publicly tested (and failed expectations). His reserves are being drained; in some cases emptied. Western weapon systems are being field-tested, at the low-low cost of their purchase cost, plus shipping and handling.

It took a while for me to realize that the West doesn't want Ukraine to win, outright. First, they want Ukraine to bleed Putin until he's too feeble to stand. That will take a while.

Because they are scared of Putin firing nukes. Also training an air force takes alot of time and money, only USA and China can really do it tbh.

Good strategy is to just wear down till they run out of people able to fight. Ukraine is at about 10% of the way there. It won't take all that long - in any case, if Ukraine is to be defeated it will happen for demographic reasons (lack of births due to female emigration and men ageing out of service), not through combat attrition. ~20 years down the road when it happens, Russia will be so demographically weakened through it's losses it won't be of much threat to anyone.

It is a good strategy only if you don't think about the lives lost.

And what a good strategy be like?

Making Putin understand that this war leads him nowhere, without going as far as threatening the existence of Russia.

This means US/NATO planes above Ukraine are OK, but not above Russia.

And those planes should do what over Ukraine?

Put simply, bomb enemy ground forces.

Aha, US/NATO jets bombing Russians. Sure, seems like a solid plan.

* Russians invading Ukraine.