I think some of you are way, way ahead of yourselves after five days.
I don't think any options should be off the table, including a no fly zone. Russia doesn't get to just do whatever they want because they can scream "nukes!". It wasn't like that for 40 years of the Cold War (when the world was much more closely balanced on each side), and it's not like that now.
On the other hand...its been five days. War is hell and we haven't seen this kind of war for a long time, our whole lives for most of us, and we've NEVER seen it this up close. We're not, nor should we be, shooting down Russian planes in less than a week.
This is very likely going to take a while, and it's going to be horrifying. Ukraine is going to continue to receive weapons and supplies from the entire world. Russia has almost no support and they won't be able to keep this up indefinitely. We shouldn't be scared, but there's a long, long way to go before we need to engage directly.