"The Final Countdown" revives a "what if?" gimmick occasionaly used on "The Twlight Zone" and "Star Trek." The carrier U.S.S. Nimitz, a few hours out of Pearl Harbor, passes through a swirling, earsplitting electrical distrubance. When the fury subside, skipper Kirk Douglas and his cohorts discover that the storm has transported them back in time to Dec. 6, 1941, as the Combined Japanese Fleet approaches for the fateful attack.

But this science-fiction cruise leaves something crucial to be depicted and resolved: After setting up the possibiltiy of a mind-boggling but emotionally stirring naval showdown, the filmmakers decline to stage it. The movie executes such a dismaying retreat from the brink of battle that the audience has a right to feel seriously cheated.

I assume that the big battle scene was avoided because the filmmakers couldn't afford the elaborate staging and special-effects work it would have required. In this shortchanged state, the movie depends on customers finding the ship and the premise diverting enough to overlook the fudging.

"The Final Countdown" -- opening today at area theaters -- achieves some photogenic distinction with its spectacular prop. The first panoramic vistas of the Nimitz at sea are awesomely witty; they echo the special effects shots of miniature spaceships in recent science-fiction adventure spectacles.But in this instance the majestic warship passing before our eyes is an authentic leviathan.

Moreover, the crew members perform with such crisp, textbook proficiency that the Navy has more justification to take pride in "The Final Countdown" than the Hollywood contingent pretending to run the show.

The most attractive of the make-believe crew members is James Farentino as the leader of a fighter squadron. Since he's also a naval historian, conveniently researching the events that culminated in the attack on Pearl Harbor, he lends the plot a timely perspective. He would also be the best conceivable protagonist for this particular time-travel fable, a point the screenwriters seem dimly aware of.

They find it easier to establish banal prespectives by placing outsiders on the ship. martin Sheen, last seen tracking down Marlon Brando's Capt. Kurtz in "Apocalypse Now," reappears in "The Final Countdown" as some kind of civilian consultant snooping around to improve efficiency.

Charles Durning and Katharine Ross play a set of 1941 civilians -- domineering U.S. senator and his standoffish Gal Friday -- rescued by Zeroes. The writers get some comic mileage out of Durning's indiganation, but the character remains expendable, a superfluous troublemaker designed to provoke incidents that divert attention from the missing climax.

Since Ross is supposed to anticipate the liberated career woman of contemporary Washington, it seems a peculiar oversight not to have a woman officer or two on board. Ross' principal acting chore is to express concern for her pet dog and anxiously inquire, "Where's Charlie?" whenever he gets out of her sight.

In addition to beating a hasty retreat, the movie leaves one puzzled about the disposition of certain details. Like casualties. One helicopter crew is lost. Some Marine guards are killed trying to disarm a captured Japanese fighter pilot brought on board to create gratuitous mischief after two F-14s make child's play of a couple of Zeroes. It's not certain whether the men apparently lost in the time warp remain lost once the ship returns to the present.

It would appear that skipper Douglas has a tall amount of explaining to do when the Nimitz returns to port in the concluding sequence. Nevertheless, the premise has been utilized so superficially that one can't discern a profound sense of apprehension or reflection from the captain down. How will he account for that missing helicopter crew and those dead Marines?

Time-travel plots of this kind require a finesse that always seems to elude movie and television writers. On one had the premise appeals to an urge, farfetched but perhaps irresistible, to alter calamitous historical events. On the other it violates a feeling tht history is inviolble. It can't be easy to satisfy the vacrious desire of seeing history changed for the better while still contriving to leave history intact.

"The Final Countdown" emerges from a round trip through this time-bending exercise flattened into a two-dimensional letdown.