Blog by an air traffic controller explains the pressures of the airline industry vs. the absolutes of runway capacities. Excerpt:
But it won’t solve the core problem -- runway capacity. Remembering the lessons above, you still need a minimum of three miles (or one minute) between landing airliners. Controllers are capable of running airplanes closer together now -- with the current radar-based system -- but safety won’t allow them to do it. Until the safety-mandated rule that only allows one airplane on the runway at a time changes, a system that allows controllers to run aircraft closer together won’t increase the runway’s capacity.
While we are on this subject, I need to call your attention to another point about wake turbulence. Wake turbulence exists behind departing and landing airliners. Behind the largest aircraft -- classified as “heavy” aircraft -- the spacing requirements increase to 5 miles. Remember that theoretical line of aircraft stretching out 180 miles from JFK airport ? Throw in a couple of “heavy” airliners and the line will stretch past Washington, D.C.
