Syria no fly-zone - Blair shot down

General Martin Dempsey, Chairman of the Joint Chiefs of Staff and spokesperson for the 'international community' has thought about no-fly zones:

“You don’t have to send in troops, but the international community should think about installing no-fly zones." Tony Blair, June 2013

Establish a No-Fly Zone. This option uses lethal force to prevent the regime from using its military aircraft to bomb and resupply.  It would extend air superiority over Syria by neutralizing the regime’s advanced, defense integrated air defense system.  It would also shoot down adversary aircraft and strike airfields, aircraft on the ground, and supporting infrastructure. We would require hundreds of ground and sea-based aircraft, intelligence and electronic warfare support, and enablers for refueling and communications.  Estimated costs are $500 million initially, averaging  as much as a billion dollars per month over the course of a year.  Impacts would likely include the near total elimination of the regime’s ability to bomb opposition strongholds and sustain its forces by air. Risks include the loss of U.S. aircraft, which would require us to insert personnel recovery forces.  It may also fail to reduce the violence or shift the momentum because the regime relies overwhelmingly on surface fires—mortars, artillery, and missiles. Link