ALNILAM by James Dickey (Doubleday: $19.95; 683 pp.)

James Dickey has been giving us tantalizing news of this novel for several years; a section of it, under the title “Cahill Is Blind,” appeared in Esquire in 1976, and in 1971, numerous notes concerning it were in “Sorties,” the first 150 pages of which were a curious exercise in the creation of a writer’s journal. To judge from the striking similarities between the novel as it now exists and the notes about it in “Sorties,” this story has been on Dickey’s mind for many years, though crucial concerns have shifted as the book evolved. In the journal, for example, there are references to the story’s relevance to the late-’60s climate of youthful protest; in the novel, the pertinence is there, but in no way insisted on.

One of Dickey’s great strengths as a poet has been his extraordinary ability to give plausibility to nearly incredible situations and events. This is harder to do in fiction, of course, but “Deliverance” demonstrated that Dickey is aware of the different ways in which the two genres present this problem. A bare summary of the events in “Alnilam” would stretch credulity, but the detailed and absorbing narrative provides the necessary background and motivation for even so outrageous a scene as that in which a blind man goes up in an airplane and wrestles the controls away from the pilot for a few minutes.

The setting is an Army Air Corps training camp in Peckover, N.C., in January, 1943. Frank Cahill, builder, owner, and operator of a swimming pool and amusement park in Atlanta, has in the previous three months been living with blindness brought on by diabetes. Though he disdains harnesses, leashes, and canes, he has amateurishly trained a huge dog, Zack, to help him get around. He and Zack make their laborious way to Peckover on receiving news of the death of Frank’s son, Joel, in an accident. The young cadet crashes over a brush fire, is taken in briefly by a farmer and disappears into the burning woods without a trace. Five days have passed between Joel’s crash and his father’s arrival.

Frank Cahill has never seen his son; his wife left him while she was still pregnant, and they have had nothing to do with each other since. But Cahill approaches the training camp with the idea that he can conceal this fact, and learn something about the boy by talking to the people who knew him. The strength of the novel lies in the thoroughness with which Cahill enters the life of the camp for a few days, and in the gradually emerging picture we get of Joel, who has been a charismatic figure, the leader in a secret society of cadets who have named themselves after the middle star in Orion’s belt--Alnilam.

This group is an extreme example of the rebelliousness that develops among schoolboys or convicts or soldiers in training. Joel Cahill came among them with a few strange ideas gleaned from the 19th-Century poet James Thomson and from science fiction; the force of his personality has been enough to involve several cadets in rituals and secret messages, the aim of which is to mold an elite corps of pilots who will be beyond the Army’s control. The final purpose of their activity is obscure, because they are committed to such notions as “flying without the airplane.” But they manage to create considerable havoc after Joel’s death, acting on the belief that Frank’s coming to the base has been foretold to them, and that Joel is not really dead, but is still out there somewhere, directing their actions.

Cahill’s arrival at the base, and the willingness with which the commanding officer, Col. Vernon Hocclave, permits him to wander around, are made convincing partly by the circumstances themselves--Joel’s crash is the first accident to have occurred at Peckover--and partly by the sheer force of Cahill’s character. He is a big, strong man with an iron grip--he keeps a spring-grip exerciser in one pocket and plays with it at odd moments, and at one point, he manages to break an officer’s hand--and Zack, one of the more memorable animals to have appeared in recent fiction, looks more like a wolf than a dog.

But it is the existence of the small group of young fanatics that makes possible Cahill’s freedom to wander around the base, asking questions and making discoveries--about his son, about flight, and about himself and the resources he can call on to negotiate this strange environment. He has not been blind long enough to stop marveling at his rapidly developing aptitude for sensing his surroundings, and this gives the book pace-quickening intensity that makes the book feel shorter than it is.

In several passages, Dickey uses parallel columns, once in boldface representing Cahill’s sightless perceptions, and the right column representing a sighted view of the same action. Most of the time this technique works surprisingly well. The contrast is sometimes almost humorous, as when Cahill works up mental descriptions of the people he is talking to, and the right column reveals how wrong he is. At other times, these passages handle the more ambitious business of presenting a deeper impression of things than either viewpoint alone could give. Unfortunately, there are places where both columns go on unbroken for several pages, and it becomes annoying to have to decide when to switch back and forth.

There are a few brief passages in which the style becomes self-conscious, or where the intensity seems too laboriously worked up. But Dickey’s ear for Southern talk, his understanding of the sensations involved in flying, and his interest in a wide array of minor characters, make the novel rich and rewarding reading. “Alnilam” is a solid achievement.