The made-for-TV football season nears. And its approach, like that of the shuttle that landed Keith Jackson and Co. safely in Washington the other day, is guided by computers.

In case you were wondering, roughly a third of you who watch a typical NFL game on TV in the fall will forsake yardwork and cherry blossoms on a spring Sunday for a typical United States Football League game. How do we know this? Air traffic control--ABC-TV's research department--says so.

But even more important than that: the advertisers believe. The advertisers are buying. Can success be far off? Should Craig James get fitted for top hat and tails?

"Heavyweights" was the word used by Jackson, ABC's USFL play-by-play man, to describe those prescient cost-per-thousand types who, as of last week, have bought 80 percent of the commercial time for ABC's 18-game, March-through-July schedule.

"Beer," Jackson announced, the way some people might say, for instance, "Libya is ours," or "Carpools have been outlawed on I-66."

"Anheuser-Busch and Miller," he went on. "Automotive. Chevy, GM. And Ford."

Heavyweights. Barometers. Sentences without verbs.

"We're optimistic that by the start of the season, we will be sold out," Jackson said. And had anyone suggested such a thing 90 days ago, he said, surely he would have been laughed at.

Jackson, as smooth at lunchtime as gametime, was frequently laughed with the other day, never at. The room was, after all, filled with hope and good will--being as it was also filled with hopeful, willful people from ABC Sports, the Washington Federals, ABC affiliate WJLA-TV-7 and WMAL-630.

ABC, which will share the 12 teams' schedule with ESPN (with the cable sports network doing games Saturdays and Monday nights), has sold its 30-second spots based on a 5 rating (the NFL averaged 16.6 last season), which means those spots will cost $30,000 each, which is more than ABC got for NCAA football telecasts five years ago.

Which should be more than enough, in the USFL's first year, to keep a smile on the face of Commissioner Chet Simmons, the former head of ESPN and, before that, of NBC Sports.

Simmons' extensive TV background should, in 1983, surprise about as many (or few) as were slightly put off by Jackson sounding like an advertising rep for ABC Inc. when he is, in fact, going to be sitting, impartially of course, in the booth when the USFL's claim of entertainment value gets tested on the field March 6.

Then again, now is the time for optimism. But thanks nonetheless go to Lynn Swann, Jackson's expert analyst for the USFL games, for clarifying things.

"We're going to be living in the same house," he said, "but we're not going to sleep in the same bed.

"We're going to be around for a while," Swann said, speaking of ABC Sports and grinning at the Federals' management sitting nearby. "We hope you are, too."

He looked up at everyone else. "But in case they aren't," he said, "we're going to tell everyone that we saw it before it happened."

ABC also clarified other distinctions clouded by Simmons, ABC and others in months past, among them the fact that the network will not provide game officials with team-requested instant replays, a proposal some had called an "innovation," Swann and others called a "conflict" and RFK's Robert Sigholtz, also present the other day, called a good way to get 30,000 or 40,000 TV-less fans clamoring onto the field in a hurry.

"If the USFL wants to do it, they can put their own cameras on the field and do it themselves," Jackson said. When someone suggested the USFL couldn't afford it, Jackson said, "And do you know why the USFL can't afford it?"

Federals owner Berl Bernhard's face lit up. "Because of the ABC contract!" he quipped, loudly.

The real answer, which Jackson provided as the laughter subsided, is "because they would need 33 cameras."

ABC will use only eight or nine, five fed into replay machines, which is a lot in itself. The number 33, it turns out, is only the age of ABC's USFL director Craig Janoff, who probably will be among the oldest (producer Mike Pearl is 35) production people ABC will assign to the new league.

The crew is deliberately young and open to new ideas, Janoff said, among them more intimate coverage (a la director Ted Nathanson's recent Super Bowl, perhaps) and frequent college clips to help establish identities, more isolated replays away from the ball and coaches wired for sound.

Made for TV. And made for less than $20 million over two years, reportedly, from ABC.

If ticket sales continue at the pace they've started in places like Washington, Denver and Tampa Bay, and if most of these young people, on and off the field, come through with solid performances, especially early on, it could be one of the biggest bargains ABC's computers ever predicted.