Ursula Le Guin is funny. I mean, she has a deep, cosmic sense of humor --- a good thing for a writer of speculative fiction. Her new book, CHANGING PLANES, has a near-universal complaint for a premise (the tedium of waiting in airports for delayed/canceled flights) and a play on words for the title (instead of changing to flying machines bound for Memphis or Boise, people transport themselves to different planes of existence). The key to "interplanary travel," the anonymous narrator explains, is the very awfulness of the airport experience: "a specific combination of tense misery, indigestion, and boredom." You might call CHANGING PLANES the ultimate in escape reading.

After this clever set-up, the book becomes a sort of glorified travelogue. Granted, the civilizations on the various planes aren't real --- but they could be, and Le Guin's gift for inventing plausible and detailed alternative societies is as brilliant as ever. In the tradition of her eminent anthropologist parents, she creates a succession of strange lands and customs that overturn our assumptions about what is standard, settled, and normal. It's cultural relativism as you've never seen it before: witty, sophisticated, and gloriously human.

"The Silence of the Asonu" shows us a civilization in which adults don't speak. In "The Nna Mmoy Language," words have ever-shifting meanings ("Learning Nna Mmoy is like learning to weave water," a puzzled outsider says) and "Feeling at Home With the Hennebet" challenges our notion of identity and the individual soul. Often the stories are vehicles for social criticism and satire: rampant consumerism ("Great Joy"), genetic engineering gone nuts ("Porridge on Islac"), pointless wars ("The Ire of the Veksi"; "Woeful Tales from Mahigul"), and celebrity worship ("The Royals of Hegn"), to name a few. Some are surreal ("Confusions of Uñi"), while others are quietly mysterious, such as "The Building," in which a "primitive" people builds an enormous, uninhabited, apparently purposeless palace of green stone, or "The Fliers of Gy," one of Le Guin's most moving stories, which imagines a race in which a few people in every generation grow wings. Are they handicapped or godlike? The parallels to our own fear of (and yearning for) flying, risk and death are inescapable and poignant.

A strong theme in several of the stories is a mistaken idea of progress, an attempt to "fix" social systems that aren't broken. "Seasons of the Ansarac," my favorite of the collection, shows us a migratory culture in which the people, gripped by a powerful sexual drive, trek periodically from the south (seat of cities and cultural institutions, where they live in random, close-packed groups and talk all night, but never make love) to the rural north, where they have sex and procreate and cleave to their families. When the Beidr --- an aggressive, technologically advanced civilization --- sets out to save them from hormonal enslavement . . . well, you can guess the rest. The upshot is that the Ansarac no longer allow visitors to their plane; it is closed off to humans in the time-honored tradition of lost paradises (from Dante to Shangri-La), and the story ends on a note of profound longing.

"Seasons of the Ansarac" is up to Le Guin's finest work (THE LEFT HAND OF DARKNESS, THE EARTHSEA TRILOGY, and more), but I can't say the same for all of the tales in CHANGING PLANES. It's true that they are vastly intelligent and adroit, often written in a style that combines the detached, slightly stuffy observations of a scientist in the field with an attractive fable-like cadence (they'd be great read aloud). Many of them, however, seemed slight --- sketches rather than the real, completed thing. After a while I began thinking of them as fictionalized essays rather than stories. (Nor did I appreciate the line drawings by Eric Beddows. This is not a criticism of the artist; I simply think it is more fruitful for the reader to create his or her own inner vision of a character or setting --- including alien species --- than to be confronted with somebody else's version.)

I don't mean to carp, though; I'd rather read Le Guin in any form than most writers working today. That's why I picked up CHANGING PLANES while sitting in JFK last month, waiting for a flight to France. I couldn't help laughing at the irony. I'd rather have passed the time in interplanar travel, of course, but this book was the next best thing. Try it if you're shackled to a plastic airport chair or stalled on a runway and you're looking for provocative, intelligent diversion (it's small enough to fit in the seat pocket). Or read it if you have no intention of going anywhere, but are in the mood for mental adventure. You'll return home with new eyes.