All of the Pryer photograph books sell, and the subject of this is of sure appeal. But we feel it is not up to its predecessors, nor is it as good as the Floherty book, 'Beard the Airliner (Doubleday, $2.00), except that it is simpler for younger boys and girls. Captions and photographs take two children to the airport, up in an air liner, and answer some -- but not enough -- of the questions children would be sure to ask.