The United States has not introduced an air-superiority fighter since 1974, when the F-15 entered service with the Air Force. Much has changed since then. The biggest innovation has been stealth, which makes an airplane far less detectable by radar.

The only stealth aircraft in the world, however, are the US Air Force's B-2 bombers and F-117A deep- attack fighters. The F-15 still dominates the realm of aerial combat. Even so, its edge is diminishing. The Russian-made Su-27 "Flanker" is on a par with the F-15 in some respects, and it may even have the advantage in certain matchups.

Other Russian and West European aircraft now in development will further challenge the US advantage early in the next century. The Air Force warns that by 2010, air superiority can no longer be guaranteed with the F-15. Fortunately, a timely solution is available in the stealthy F-22 fighter, which the Air Force plans to be operating in 2005. It will combine stealth with such other features as supercruise--sustained cruise at supersonic speeds--to set up another long run of US domination of the air. For good reason, it is the Air Force's top force modernization priority.

Air superiority is a precondition for all other combat operations. As General Eisenhower said after the D-Day invasion, "If I didn't have air supremacy, I wouldn't be here." It has been more than 40 years since US forces on the ground had to worry about enemy air attack.

Air superiority means not only freedom from attack but also freedom to attack. The most recent example was the Persian Gulf War, where Iraqi air forces and air defenses were unable to protect critical targets or stop coalition forces from operating at will.

The F-22 program has gotten a generally favorable reception as it moved through Congress in engineering and manufacturing development status. This may be the year it gets controversial. A big budget showdown is expected in 1997 as part of the Quadrennial Defense Review. As always, aircraft programs will be among the big targets.

There is already some sentiment among the budget cutters that the three fighter programs currently under way--the F-22, the Joint Strike Fighter, and the Navy's F/A-18E/F--are excessive and that one or more of them should be eliminated or scaled back. The Joint Strike Fighter, a program to replace attack aircraft, is not out of the concept phase. The competition, if it comes to that, will likely pit the F/A-18E/F Super Hornet, now in flight testing, against the F-22, for which initial production funding will be requested this year.

The Navy is acutely aware of this and has been sniping at the F-22 for months. After two unsuccessful attempts to acquire stealth, the Navy is reconciled to flying conventional aircraft until the Joint Strike Fighter is ready. The Navy's short-term hopes ride with a "reduced radar signature" variant of the F/A-18C attack aircraft that the fleet has operated since 1985. The Navy claims the F/A-18E/F will be able to beat the Russian Su-35, the Eurofighter 2000, and the French Rafale in "overall combat effectiveness" and will not be bested before a Russian "fifth-generation fighter" appears around 2015.

That is an extravagant claim. Air Force sources say it was based on the opinion of naval aviators assembled to help the Navy make its case. The General Accounting Office was probably closer to the mark last June when it reported that the F/A-18E/F "will provide marginal operational improvement at high cost."

The Super Hornet's "bolt-on stealth" treatment does reduce the radar signature somewhat in the frontal quarter, but other aspects of the signature are not reduced at all. The structural gains, such as they are, are diminished when the Super Hornet is loaded with weapons and fuel, which it must carry externally.

The Air Force investigated a "bolt-on stealth" variant of the F-15. The amount of "stealth" achieved was modest, and the cost for a third of the relative combat effectiveness of the F-22 amounted to 90 percent of the cost of the F-22 itself.

It is obvious that the Navy believes in the Super Hornet, so perhaps it is just what naval aviators need. But they should not pitch it as the dominant air-to-air fighter of the next 15 years. It is not up to that.

If we want air superiority in 2010, we had better get on with the F-22. The goal is not parity or slight advantage. It is overwhelming advantage. We must defeat opposing fighters, air-defense radars, and surface-to-air missiles by a decisive margin. The mission requires an airplane that will not only fly undetected and see the enemy first but also outfly and outmaneuver the enemy in combat engagements.

The Defense Science Board notes that the F-22 is "very ambitious technically." The inherent difficulty in keeping such a program on track establishes another point of vulnerability. The Air Force, closely watched by Congress, will have to work the cost and performance problems relentlessly when they arise. Program managers have been there before on other systems that pushed the state of the art.

If the F-15 holds air superiority for 30 years, let us marvel and give thanks but realize that this cannot go on forever. The time has come for a new air-superiority fighter, and the F-22 is it.