Even though I haven't ridden it for eight years or so -- the train and the car are more my financial speed-- the Eastern Airlines Air-Shuttle has always intrigued me. The reason is the famous "Shuttle pledge."

Ever since it was born 21 years ago, the Shuttle has promised to fly you to or from New York at the hour you show up -- even if you turn out to be the only passenger on the plane.

You've got to admit that the fantasy possibilities of having an entire aircraft to yourself are delicious. Seven stewardesses to take your fare, and to ask why you're so charming. No crotchety accountant in the next row to steal the copy of Sports Illustrated on which you had your eye. Leg room like gangbusters.

But Shuttle Solos take place only in your dreams. To give someone a private trip would cost Eastern about $10,000 in jet fuel, employes' salaries and takeoff and landing fees. For that reason, it has been at least 18 years since the last one-passenger flight, according to Jim Ashlock, director of Eastern's news bureau. And solos have happened only about a dozen times in the Shuttle's existence, Ashlock said.

What accounts for the slide? Partly the popularity of the Shuttle, Ashlock said, and partly good old-fashioned bluffing.

"In the old days, before the Shuttle was so popular, you might get a guy who's held up in traffic trying to make the 4 o'clock Shuttle. He gets to National Airport at 3:59. Our pledge means we couldn't ask him to wait until 5. And the Shuttle wasn't popular enough for there to be a lot of people waiting for extra sections. So off he went, by himself."

Today, "we'll usually find that a lot of people are still lined up on the stroke of the hour, waiting for extra sections to load and leave. So most of the people can just catch one of them. We have extra sections enough of the time that it's very, very rare for us to have exactly one guy more than the planes will hold."

But what if you do?

"Well, if he insists, we'd have to take him. We just hope he doesn't insist. And if it looks like he's about to, we give him a long look and hope he volunteers to wait a few minutes for the 5 o'clock.

"They all seem to understand. So far."