See: http://www.nordicgroup.us/bikerec/images/aloha243.jpg

From: http://www.nordicgroup.us/bikerec/

"Invariably, when the aluminum versus steel debate pops up, someone chimes in with an analogy about airplanes. They ask why we're not worried about aluminum airplanes falling out of the sky, but we're worried about aluminum bicycle frames breaking. I'm convinced that buried somewhere in the sales training from Trek, Cannondale, and/or Specialized, there is an FAQ that tells salespeople to use the airplane analogy to address concerns from customers about aluminum framed bicycles.

Like most analogies, it's a poor one. The fact is that we are worried about airplanes falling out of the sky. Recall the 1988 incident in Hawaii where an Aloha Airlines Boeing 737 suffered a structural failure. This was an inter-island plane, which had an abnormally high number of compression/decompression cycles, which fatigued the aluminum skin, causing stress cracks that propagated from rivet locations. Amazingly, only one person was killed (a flight attendant who was sucked out during the decompression). Of course the solution here was not to make airplanes out of steel, it was to increase inspections, and limit the number of stress cycles before an aircraft is taken out of service."