Senators John Kerry (D-Mass.) and John McCain (R-Ariz.) have both encouraged the Obama administration to consider a n0-fly zone over Libya. It seems to me that it's important to point out that this really means "war."
When the U.S. instituted a no-fly zone over southern Iraq in the 1990s, the Air Force attacked the Iraqi air defense system so relentlessly that its radars rarely were turned on, allowing U.S. and allied fighters to patrol without suffering any combat losses for more than a decade.
In the initial stages of a no-fly zone over Libya, air defense batteries might test NATO pilots. With Kadafi and his supporters desperately clinging to power, there is also the possibility that at least some Libyan fighters would attempt to engage NATO aircraft, several officers said. The Libyan air force flies Vietnam-era, Soviet-designed MIG fighters that are not considered much of a threat to U.S. aircraft.
Even so, retired Air Force Lt. Gen. David A. Deptula said, "If you are going to do this, you have to be prepared for the possibility that aircraft are going to be engaged in combat."
To carry out patrols over Libyan airspace 24 hours a day, the U.S and its allies would need hundreds of aircraft, including fighters and refueling tankers, Dunn said. The U.S. could reduce the number of aircraft required by flying only during the day, when attacks on anti-government rebels are most likely, or by going after only Libyan airplanes, not helicopters, he said.
My brother John, at CNBC puts it well:
The very first step in establishing a no-fly zone would be a bombing attack on Libya. Our bombers would have to seek out and destroy Libya’s air defenses. Bombing another country is called war. We’d be converting a nascent civil war in Libya into an international war lead by the United States.
Maybe you have enough room in your heart for a third war in the Islamic world, but I'm not sure how many of your countrymen or politicians are similarly disposed.