It didn't figure that Air Force, which hadn't won in five games and couldn't beat Yale last week, would step up in class and upset Navy today. Nor did it figure the Falcons, a wishbone team that has not been able to pass successfully against anyone this season, could shock the Midshipmen by throwing the ball accurately.

But Air Force proved that being highly unpredictable sometimes can lead to the unexpected. The Falcons ended a surprisingly successful passing show when wide receiver Andy Bark with 62 seconds left for a 21-20 triumph that left Navy Coach George Welsh digusted with his club's performance.

"We didn't play on offense or defense, we were awful," Welsh said as he tried to digest a game in which his quarterback, Fred Reitzel, a 60-percent passer, completed only three of l9 attempts and his team couldn't put things out of reach despite four Air Force turnovers.

Navy was leading the nation in total defense and scoring defense entering the game. It will drop in both rankings next week after surrendering 286 total yards to an opponent that had been held to 10 or less points three times this season.

Welsh was so upset with Navy's display that he couldn't even get very worked up over a questionable pass interference call that set up Air Force's winning touchdown after the Mids had gone in front earlier in the fourth period.

The penalty came on a second-and-l0 play from the Air Force 42 with 90 seconds remaining. Freshman quarterback Marty Louthan, who had replaced injured starter Scott Schafer on the previous series, overthrew Bark by a good 10 yards. Then the Falcon receiver and Navy's Elliott Reagan collided. The official closest to the play didn't drop a flag, but another came from 15 yards away to call interference.

"I didn't see interference out there, but what can you say?" Welsh said. You get calls like that, although it probably wasn't a good one."

The call stood and Air Force had the ball at the Navy 34.After two incompletions, Louthan tossed up a desperation heave toward the corner of the end zone. Bark, who had seven catches for 152 yards, and Reagans both went up for the pass. Reagans had splendid defensive position, but somehow Bark won the midair wrestling match and fell to the ground with a touchdown.

As the home crowd cheered widly, Sean Pavlich kicked the conversion and Air Force had finished off a shocking turnabout.

Air Force, which carried a 0-4-l record into the game, was limited to 94 rushing yards. But the Falcons, a 38-percent passing club before today, completed 11 of 20 passes for 192 yards, including seven of 11 for 126 yards in the second half.

Still, Navy should have won the game. Air Force tried to hand it away all afternoon. The Falcons turned the ball over at their 33 (resulting in a 34-yard Scott Fehr field goal), at the 23 (resulting in a ll yard Ed Myers touchdown run,) at the 44 (resulting in a punt) and at the 23 (resulting in Reitzel's one-yard scoring plunge.)

It would have helped the Middies considerably if Reitzel, who had been playing so well in his first year as starting quarterback, had not passed like this was his first introduction to football.

In the first half, he was plagued by five dropped passes. In the second, when he failed on all six of his attempts, he didn't get the ball close enough to most of his receivers to have anything mishandled. And he had been the nation's sixth-rated passer.

With Reitzel throwing blanks, Welsh had little choice but to rely on his running game. That strategy almost was enough. Navy gained 271 yards on the ground -- Meyers had 94 yards and Duane Flowers l00 --- and controlled the ball 10 more minutes than Air Force. And when Reitzel pounded over from the one with 8:22 left after the final Air Force turnover, it appeared the Mids might escape.

Their case seemed even more solid when they held the ball for four minutes late in the fourth, relying entirely on running plays to move to the Air Force 27, when they faced a fourth and two with two minutes to go.

Welsh said he thought Fehr could kick successfully from at least 50 yards, with a swift wind at his back. "But I didn't want to risk a blocked field goal that would give them possession at midfield," he said. "And if we get a first down, the game's over, too. But the length of the field goal and the possibility of the block made me decide to go for it." Flowers swept right end, but Air Force was stacked to stop the play. He was halted for a two-yard loss (Navy also had a holding penalty, which was refused) and Air Force took over with 1:40 to go.

Still, the odds favored Navy. Schafer, who had scored twice and kept the Middie defense offbalance with his first-half running and second-half passing, was on the sidelines with a leg injury. Louthan, playing in his place, had completed only four of 22 passes in his short college career. But, somehow, the Falcons managed to pull it out.

"Whether we got the first down or not at the end, we probably would have lost anyway," a downcast Welsh said. "When things go wrong for you, everything breaks down. They deserved to win."