[Goose]

Seems like a lot of countries fly the F16, why not offer a "Flying Tiger" deal to any countries F16 pilot who is willing to move to Ukraine. But then they might need more planes too.

Each country that has "candidates" would have to have its own program. Ukraine would also have to agree the "Fighting Tiger" approach is acceptable and practical for them. There may be political and logistical issues that make such a plan impractical. I am surprised actually that Ukraine has not called for such a program, at least to fully staff the F-16s it already has. It could be they were told it was off the table, but it also could be for other reasons.
 
Many European countries have anti-mercenary laws that forbid their citizens from participating in wars that their homeland is not. These laws would be a problem to work around. The air forces of Europe that are converting over to the F-35 from the F-16 are relatively small, so losing a quantity of pilots is problematic for them. Most of these countries do not intend to continue using the F-16 at all so in order to stay in their air force conversion to the F-35 is necessary. Nobody will want to miss that unless they intend to leave the air force. That may yield some volunteers, but not many.
 
The US intends to continue using the F-16 for quite some time in our "high-low" mix. Our F-16 fleet even today dwarfs any European one. That means going to Ukraine to fight doesn't end your career. We also obviously have many more potential candidates. Most people won't be interested. It requires pilots with a bit of Boyington in their psyche to chose such a path. For these reasons, in order to make numbers, most of the pilots will have to be US.
 
It is unclear how many aircraft Ukraine actually has at the moment. The total promised as I understand it is 54. They are not all delivered yet, I think. IMO that isn't enough airplanes to day-in day-out neutralize the increasing level of Russian drone activity. An average of 234 targets per day and 50% aircraft/pilot availability would require each pilot to destroy 8-9 targets. That may not be even possible if Russia coordinates the drone arrivals to minimize Ukraine's opportunity to use one aircraft to attack multiple targets. These attacks right now have to happen inside Ukrainian airspace. Unfortunately many of the important targets are near the line of contact/Russian border. That means the time of flight inside Ukrainian air space is limited. Attacks against Odesa and Zaporizhzhia are much easier to deal with than attacks on Kharkiv. A Shahed drone crossing the Russian border at the closest point will spend less than 6 minutes in Ukrainian airspace before reaching targets in "the city". Kyiv would be "easy" to defend if Russia respected Belorussian air space. The time of a drone in Ukrainian airspace would be almost 90 minutes. Since Russia does not respect Belorussian air space, the actual time is about 40 minutes. Still much better than Kharkiv.
 
For these reasons I don't think 54 aircraft will be "enough". Ukraine also doesn't want to dedicate their entire F-16 force to drone suppression. Israel (and the US on their behalf) has the luxury of intercepting Iranian drones over other nation's airspace, i.e. Jordan, Syria,  Iraq and Lebanon. There are all sorts of game theory approaches that Ukraine and Russia will mutually use to fight the drone battle. The very low speed of the Shahed drones is a big handicap that partially compensates for Ukraine's lack of real-estate. In both Israel and Ukraine a good radar picture of the target space is critical to intercepting these mass attacks. It will never be possible to have as many F-16s as the enemy has drones. How many aircraft are required for any given notional attack can be calculated. I haven't done this but I assume Ukraine and the US have. My estimate is somewhere in the 50 available aircraft range for a 250  drone strike. There will be some leakers for the point defense SAMs to deal with. The SAMs are "good" for that. The required number of aircraft curve has a slope of less than one. Two drones on similar paths at similar times most often do not require a second airplane. Once a saturation point is reached more drones don't help much other than exhausting the ammunition of the interceptors. That is why the APKWS (and even cheaper systems in the future) are important. An F-16 can carry 6 AIM-9Xs. These missiles are massive overkill against Shahed drones. 42 APKWs are lots better.

[Goose]

Seems like a lot of countries fly the F16, why not offer a "Flying Tiger" deal to any countries F16 pilot who is willing to move to Ukraine. But then they might need more planes too.

Each country that has "candidates" would have to have its own program. Ukraine would also have to agree the "Fighting Tiger" approach is acceptable and practical for them. There may be political and logistical issues that make such a plan impractical. I am surprised actually that Ukraine has not called for such a program, at least to fully staff the F-16s it already has. It could be they were told it was off the table, but it also could be for other reasons.
 
Many European countries have anti-mercenary laws that forbid their citizens from participating in wars that their homeland is not. These laws would be a problem to work around. The air forces of Europe that are converting over to the F-35 from the F-16 are relatively small, so losing a quantity of pilots is problematic for them. Most of these countries do not intend to continue using the F-16 at all so in order to stay in their air force conversion to the F-35 is necessary. Nobody will want to miss that unless they intend to leave the air force. That may yield some volunteers, but not many.
 
The US intends to continue using the F-16 for quite some time in our "high-low" mix. Our F-16 fleet even today dwarfs any European one. That means going to Ukraine to fight doesn't end your career. We also obviously have many more potential candidates. Most people won't be interested. It requires pilots with a bit of Boyington in their psyche to chose such a path. For these reasons, in order to make numbers, most of the pilots will have to be US.
 
It is unclear how many aircraft Ukraine actually has at the moment. The total promised as I understand it is 54. They are not all delivered yet, I think. IMO that isn't enough airplanes to day-in day-out neutralize the increasing level of Russian drone activity. An average of 234 targets per day and 50% aircraft/pilot availability would require each pilot to destroy 8-9 targets. That may not be even possible if Russia coordinates the drone arrivals to minimize Ukraine's opportunity to use one aircraft to attack multiple targets. These attacks right now have to happen inside Ukrainian airspace. Unfortunately many of the important targets are near the line of contact/Russian border. That means the time of flight inside Ukrainian air space is limited. Attacks against Odesa and Zaporizhzhia are much easier to deal with than attacks on Kharkiv. A Shahed drone crossing the Russian border at the closest point will spend less than 6 minutes in Ukrainian airspace before reaching targets in "the city". Kyiv would be "easy" to defend if Russia respected Belorussian air space. The time of a drone in Ukrainian airspace would be almost 90 minutes. Since Russia does not respect Belorussian air space, the actual time is about 40 minutes. Still much better than Kharkiv.
 
For these reasons I don't think 54 aircraft will be "enough". Ukraine also doesn't want to dedicate their entire F-16 force to drone suppression. Israel (and the US on their behalf) has the luxury of intercepting Iranian drones over other nation's airspace, i.e. Jordan, Syria,  Iraq and Lebanon. There are all sorts of game theory approaches that Ukraine and Russia will mutually use to fight the drone battle. The very low speed of the Shahed drones is a big handicap that partially compensates for Ukraine's lack of real-estate. In both Israel and Ukraine a good radar picture of the target space is critical to intercepting these mass attacks. It will never be possible to have as many F-16s as the enemy has drones. How many aircraft are required for any given notional attack can be calculated. I haven't done this but I assume Ukraine and the US have. My estimate is somewhere in the 50 available aircraft range for a 250  drone strike. There will be some leakers for the point defense SAMs to deal with. The SAMs are "good" for that. The required number of aircraft curve has a slope of less than one. Two drones on similar paths at similar times most often do not require a second airplane. Once a saturation point is reached more drones don't help much other than exhausting the ammunition of the interceptors. That is why the APKWS (and even cheaper systems in the future) are important. An F-16 can carry 6 AIM-9Xs. These missiles are massive overkill against Shahed drones. 42 APKWs are lots better.