Two important story characters — Lieutenant Ned Ordway, the airport’s police chief, and Perry Yount, an air traffic supervisor — were each referred to in the 1968 edition as a “negro.” At that time the description was normal, acceptable and inoffensive and, with millions of book copies in forty languages, I have not received a single complaint. However, I concede that more recently the label “negro” has become offensive, and therefore is not repeated in this new edition. Instead I have used “African-American,” a phrase seeming to enjoy wide favor.