Tightly-coupled systems

Loosely-coupled systems is a concept in which I am interested. I recently read a good counter example of a tightly-coupled system that I want to remember for illustrative means. The scheduling of airline flights. Some quotes:

"In a less efficient era, the waste of simple back-and-forth scheduling might have meant an extra aircraft or two just waiting idly, costing the airline money, but luckily available to fill in for the out-of-service DC-10. Now, with scheduling approachign perfection, less than 2 percent of American's fleet lies fallow at any given moment. So the nearest replacement plane happens to be in Dallas. A crew must fly it to Chicago."

"The paradox of efficiency means taht as the web tightens it grows more vulnerable to small disturbances -- disruptions and delays that can cascade through the system for days."

"Networks like this are said to be tightly coupled. A complex construction project with a timeline scheduled with perfect efficiency, all the slack squeezed out of it, may be tightly coupled and a candidate for serious disruption."

"Charles Perrow, in his study Normal accidents, extended the concept to complex systems where the coupling connects not physical parts but abstract services, people, and organizations. 'Looselyl coupled systems, whether for good or ill, can incorporate shocks and failures and pressures for change without destabilization,' he notes. 'Tightly coupled systems will respond more quickly to these perturbations, but the response may be disastrous.'

Gleick, James. Faster: the acceleration of just about everything. Pantheon Books, New York, 1999, pp. 219, 223, 224.