No one knows the exact figure; however, it has been estimated that daily in 1978, approximately 10,000 persons boarded U.S. airline planes for the first time. Even if that number were cut in half, it still would add up to a considerable number of Americans being introduced to air travel. And this does not take into account the thousands, perhaps millions, of rather inexperienced air travelers who were coxed into airliners by the proliferation of low fares. Also, those not having flown more than once or twice before probably could be put into the same category as first-time passengers.

Thus, there is a distinct need for a book like The Air Traveler's Handbook . Certainly its subtitle is justifiable: I could find no subject that this handsome, beautifully illustrated volume did not cover -- from how to overcome fear of flying to a glossary of aviation terms that would make an instant expert out of anyone committing it to memory.

Twenty writers, recognized experts in their fields, were the contributors but, unlike so many multiple-author works, this one has a continuity of style that could have only come from expert editing and, I suspect, inevitable rewriting. The final product makes for almost an overnight course in a highly intricate subject. From the complexities of air traffic control to full-color reproductions of airline insignia, the Handbook covers it all. Most importantly, the technical topics have been transformed into laymen's language without the patronizing, phraseology that afflicts so many such efforts.

I cannot state strongly enough that I feel this to be an honest, straightforward job with no trace of puffery or sugarcoating of the unpleasant. For example, there are several pages on aircraft emergencies: the reader is instructed without being frightened to death. Surely helpful material of this caliber belongs in airliner seatpockets -- provided you could get apathetic passengers to read it.

The Handbook is slightly dated; its most recent statistics cover the year 1977, but this certainly is not major flaw. It succeeds at its primary goal -- education -- not just admirably but exceptionally well. I kept going over it trying to spot some omission that I felt a book of this kind should have covered, bu-t I couldn't turn up a single one. I even leaped at the section titled "Economics of Air Travel" only to discover that the term "load factor" had been thoroughly explained.

The greatest praise that can accorded this Handbook is its universal appeal. Originally produced and published in England (where some of the most magnificent aviation books have been done), it would be invaluable to a "rookie" air traveler, but it also belongs on the bookshelves of every aviation buff. The only thing it doesn't do is explain those 30 or so different fares between Washington and Chicago, and this may be well beyond the comprehension of anything short of an IBM computer. (Simon and Schuster, paperback, $8.95; cloth, $14.95)