February 3, 1986

AS Billy Olson put it, it has been ''a pretty unusual year.'' Unusual, indeed. In his first three track meets this winter, he set world indoor bests for the pole vault of 19 feet 2 3/4 inches, 19-3 1/2 and 19-3 3/4. In his next two meets - Friday and Saturday nights - he could not clear his opening heights. Adding aggravation to aggravation, he learned that Joe Dial had bettered his world indoor bests Saturday afternoon. In pole vaulting, where a slight imperfection can translate into disaster, disaster struck Olson Friday night in Toronto. He failed to clear his opening height of 18 feet 8 1/4 inches.

The space shuttle Challenger's solid-fuel booster rockets were not equipped with sensors that could have warned of trouble because designers thought the boosters were ''not susceptible to failure,'' the head of the space agency said today. The right-side booster rocket is the prime suspect in the explosion Tuesday that destroyed the craft and killed the seven astronauts aboard. William R. Graham, Acting Administrator of the National Aeronautics and Space Administration, said the solid-fuel booster rockets were ''some of the sturdiest parts of the entire shuttle system.'' 'Designed With Great Care' ''They are considered primary structure, and not susceptible to failure,'' Dr. Graham said. ''We designed them that way. They were designed with great care and great thought.''

The crisis now confronting City Hall has yielded a revealing byproduct: it has forced Mayor Koch to consider reforms he has either opposed, or declined to pursue, since he became the city's chief executive. The events of the last few weeks have also thrown into high relief Mr. Koch's apparent willingness to jettison friendships and political alliances if they carry with them a potential risk. In many ways, the Mayor's evolving reaction to allegations of an extortion and bribery scheme in the city's Parking Violations Bureau can be seen as a paradigm for the way he often reacts to substantive criticism and keeps it from coming too close to him. First come mayoral anger and criticism, often accompanied by a lashing out at critics and their criticism and often blaming others for what went wrong. Then, in the face of changing public opinion, he embraces the very same criticism, an approach that serves effectively to defuse it.

Something strange yet intriguing is happening to the Knicks. In their last two games, they have proved that they are indeed a team, a collection of talent that can overcome a sub-par performance by their dominating rookie center, Patrick Ewing. But what is more staggering is that tonight, before a hostile sellout crowd here at the Forum, they proved it against pro basketball's defending world champions. In perhaps their most complete performance of the season, the Knicks dominated the Los Angeles Lakers in rebounding, smothered their vaunted fast break and, most surprisingly, overcame Ewing's worst performance of the season to emerge with a 103-96 victory.

''There have been ups and downs of Communism, but this is not that - it is an irreversible regression.