I am often amused by the consequences of the Law of Unintended Consequences:
The law of unintended consequences, often cited but rarely defined, is that actions of people—and especially of government—always have effects that are unanticipated or unintended.
The Concise Encyclopedia of Economics
Recently Newsweek ran a story titled Is Boeing’s 737 an Airplane Prone to Problems? In brief, Newsweek cites several cases in which the outer skin of a Boeing 737 separated during flight. Rapid decompression of the cabin ensued, creating an in-flight emergency. In the 1988 case of an Aloha Airlines flight a large section of the forward upper fuselage blew completely off the aircraft, falling into the ocean along with a flight attendant. Seven passengers were seriously injured, but the pilots managed to land what was left of the aircraft.
In April 2011, a 5 foot by 9 inch section of the fuselage of a Southwest Airlines 737 peeled off over California. The plane landed safely with no serious injuries to passengers or crew.
In both cases the sudden decompressions were brought on by the failure of lap joints where skin sections are joined to each other, and to the airframe, by rivets and some glue. Every time a transport aircraft takes to the air, it is pressurized so that the passengers don’t suffocate. At 35,000 feet in an unpressurized airplane, passengers would be unconscious in half a minute and dead in about 10, so pressurizing is generally considered good for business.
But, over time, pressurizing takes its toll on aircraft since the skin stretches and contracts with each pressurization and depressurization. Aircraft have to be inspected regularly to ensure that these pressurization cycles have not elongated the rivet holes attaching the skin. Once elongated, these holes are weakened, creating the possibility of a decompression.
So how do the smokers figure in to all of this? Prior to April 1998, when smoking was banned on all US flights, aircraft inspectors would just look for skin joint rivets that had nicotine stains around them, a sure sign the joint was leaking and in need of repair.