David Pogue, writing for the New York Times:
Q: “Many of the three-letter codes for airports make no sense.”
A. The non-obvious ones are probably holdovers from the airports’ previous names. “MCO is derived from MCCoy Field, the original name for Orlando International. Chicago O’Hare’s identifier, ORD, pays honors to the old Orchard Field.”
I should mention, by the way, that this book is frequently funny. For example, the author notes, “A campaign was launched in 2002 to change the identifier for the Sioux City, Iowa, from SUX to something less objectionable. The campaign failed.”
Poor Siouxlanders. :(