mvgossman writes:

To restrict aircraft movements in sensitive areas is not workable
unless accompanied by an F-15 in the air ready to shoot airplanes down.
Virtually every sensitive structure is within 5 miles of uncontrolled
airspace at a decent altitude, which, if a madman were at the controls,
is 2.5 minutes from impact in my small airplane. And all of these sites
are mere feet from a Ryder truck full of fertilizer and fuel oil. No
way to counteract airplanes without surface to air missiles such as the
White House is said to have.

A suicidal pilot in a plane isn't likely to be discouraged by the
prospect of being shot down, nor is shooting him down likely to stop
him from accomplishing his purpose. If the aircraft is loaded with
biological or radiological toxins, they will be spread effectively
whether the plane crashes at the controls of the pilot or explodes
when struck by a missile. Either way, it's mission accomplished for
the nut case in the cockpit. From what I've read, not too many people
have thought of that.

--
Transpose mxsmanic and gmail to reach me by e-mail.