This is interesting:
The pilot of a Syrian MiG 21 fighter jet who flew his plane to Jordan on Thursday asked for political asylum on landing, Jordanian Minister of State for Information Samih al-Maaytah said.
Khaddafi saw a couple pilots (or at least one) defect and fly their planes to Malta, if I recall. And he managed to keep fighting a long time. So I'm not saying that this means the Assad forces are about to crack.
But it looks bad for Assad. So the question is, as the ground forces struggle against an expanding rebellion, can Assad risk committing his air power to the fight at the price of occasional additional defections?
The fear of how more pilot defections would look could be a more effective no-fly zone than any UN-authorized and NATO-manned air patrol.