We can't just give them planes. The Russians have an advanced air defense system so they can shoot down the planes flying over their territory.
Aircraft will be lost. People will die. The thing is, the proximity of the fighting is going to make air defenses visible and susceptible when they fire to even artillery. Tactical bombing of artillery positions, trench lines, and mine fields, would change it from stagnation to Ukraine advancement. The war ends when Russia is off Ukrainian soil, Ukraine doesn’t need to overfly Russia.