It's not fair to show Fred Astaire having a make-believe heart attack on the screen except in the cause of a genuine dramatic whopper. Though 78 now, Astaire still has his status as a symbol of agelessness to think about; we expect him not to betray it.

Casting him in something as flat, pat and tentative as "A Family Upside Down," the NBC drama special Sunday at 9 p.m. on Channel 4, is like asking Don Rickles to play Hamlet. This is not what we want to see, and we have a right not to want to see it.

The film, written by Gerald diPego and directed all to delicately by David Lowell Rich, is supposed to dramatize what happens when an elderly couple is separated by the husband's illness; mom, played by Helen Hayes, goes to live with her son and daughter-in-law while gramps recuperates, and this leads to adjustment troubles for one and all.

Certain responsive chords are struck - inevitably, considering the fact that accommodating elderly relations is a common dilemma - but the script takes a tippy-toe approach, pussyfooting so perfunctorily from person to person and problem to problem that it becomes more of a list than a play. Compared to Loring Mandel's "Do Not Got Gentle Into That Good Night," which had a similar theme, "Upside Down" comes off like gossip overheard on a bus.

Ross Hunter, who retreated from theatrical pictures after the rollicking flop of "Lost Horizon," produced this special and lavished upon it not care but carefulness; if there's any emotional chaos. It's the most orderly chaos imaginable, and therefore irrelevant. The prevailing level of sophistication can be gauged by the way the title is alluded to twice in the first half hour( Efrem Zimbalist, who plays Astaire's son with all the vivacity of a Maalox tablet, notes how time has reversed rolse for his father and himself.

A family "upside down - get it? Oh, you got it.

Astaire, though he can hardly convince us he is the retired house painter alleged by the script, has a few touching moments with young Brad Rearden, as the teen-aged grandson. The kid's good, and so's the old man, but Helen Hayes simply stalks through the story like the institution she's too often been claimed to be.

Hayes doesn't interact with the other players, she's the bionic granny. Though a year younger than Astaire, she seems, spiritually, decade older. Her character remains generally perky and cuddly, except for the obligatory passing crises, and we never believe she has any real problem beyond being, like "Family Upside Down," a tolerable but stultifying drag. '60 Minutes'

The CBS news magazine "60 Minutes" breaks with two precedents on this week's telecast, Sunday at 7 p.m. on Channel 9. For the first time, the entire hour has been devoted to a single subject and all the reportage was acquired from an outside source.

England's BBC was the source and the program offers a condensed version, with new narration by Mike Wallace, of BBC reporter Tom Mangold's troubling study for modern-day terrorism, "Terror International," which links a number of terrorist activities over the last decade to a global alliance of radicals - a kind of Fourth World in which code names, rhetorical "isms" and political murder all flourish."

There is certainly no time out on this edition for even semicomic relief - such as last week's curiously delightful segment on the phony diploma trade - but the program modulates from the merely alarming to the prodfoundly disturbing. A woman terrorist, asked if murder is an acceptable instrucment of social change, replies, "What 'murder?'" and nearly giggles.

Earlier the survivor of a hijacking recalls the shooting by terrorists of the airplane's captain. She remembers being surprised that the gunshots that killed him sounded strangely "dry" and not like those she had heard "in American movies."

This is stong stuff for a Sunday evening and one hopes that regular viewers of "60 Minutes," accustomed to being served what are often tasty slices of information pie, will not be turned away by the seriousness of the subject and, appropriately, its treatment. One may shudder to think but that shouldn't keep television news from giving us something to shudder and think about.