Fairfax County School Superintendent Robert R. Spillane last night proposed an operating budget for next year with the smallest spending increase in a quarter century, but still found money to keep elementary students in school a full day on Mondays.

At a time when Fairfax and other area jurisdictions are facing bleak economic forecasts, Spillane's $903.7 million proposal calls for a 3.2 percent spending increase while tightening expenditures almost across the board and eliminating cost-of-living raises for teachers.

The biggest surprise of the evening was Spillane's decision to resurrect his proposal to lengthen Mondays for the county's 72,000 elementary students, just seven weeks after the School Board narrowly rejected a similar plan. Elementary students are now dismissed up to 2 1/2 hours early on Mondays to give teachers more time to plan classes.

Board members, PTA activists and teacher union leaders who thought the bitterly fought issue had been settled for at least a year were surprised at best and outraged at worst.

Spillane told reporters yesterday: "I'm not a politician. I'm not here to make people happy. My job is to make recommendations to the School Board . . . . I believe with every ounce of my 34 years in education that this is the right thing to do."

County Council of PTAs President Jane Strauss said she was shocked at his move and found it "very discouraging." Fairfax Federation of Teachers Vice President Mark Glofka called it "infuriating." School Board member Letty A. Fleetwood (Providence) described it as "an act of insubordination" and said she "wouldn't be disappointed" if Spillane resigned.

"This clearly has no instructional basis," said Rick Willis, executive director of the Fairfax Education Association teachers union. "It's simply, I think, a Bronx cheer from the superintendent of schools to the School Board and community that two months ago made a decision not to do this."

But School Board Chairman Kohann H. Whitney (Centreville), a strong supporter of a longer Monday, defended Spillane's prerogative to reintroduce the idea. "He showed he has the courage of his convictions," she said.

The Monday plan stands in contrast to the cost-cutting measures Spillane proposed in order to live with sharply reduced state aid and limited local funding.

Besides cutting cost-of-living raises for teachers, the budget would eliminate the positions of 60 administrators not assigned to school buildings and hold nearly all other spending flat regardless of inflation.

The operating budget pays for the day-to-day costs of running the Fairfax school system, whose 130,000 students and 188 schools make it the largest district in the Washington area and the 10th-largest in the nation. After public hearings Jan. 28 and 29, the School Board is scheduled to vote on the budget Feb. 19 and forward it to the Fairfax County Board of Supervisors.

With Gov. L. Douglas Wilder cutting state education aid to Fairfax by 12 percent next year, Spillane is relying on a 6 percent increase in local tax money from the Board of Supervisors, which finances most of the school budget.

In addition, his budget counts on $13.5 million in reserve funds -- accumulated from surpluses and by trimming textbook and other supply funds -- and predicts his staff will be able to squeeze an additional $5.6 million in savings from the current budget before the end of the fiscal year on June 30.

Although he did not carve into existing programs, Spillane did propose getting rid of 60 administrators, or roughly 3 percent of the bureaucracy, largely through attrition.

In addition, Spillane proposed eliminating an assistant principal position at each of four intermediate schools with low enrollment and getting rid of about 11 special teachers who travel from building to building. The budget also calls for cuts in spending on capital projects, printing, and cars and trucks owned by the system.

Except for fuel and other utility costs, no program would receive money to compensate for inflation, which was running at about 6.1 percent in the Washington area as of November. If the cost of paper goes up, for instance, schools would simply have to buy less paper, officials said.

By freezing teacher salaries, Spillane would begin scaling back the large increases Fairfax teachers saw in the late 1980s, when the county awarded 30 percent raises over three years to win support for Spillane's merit pay program.

While teacher unions expected the salary freeze, they didn't expect the revival of the Monday-extension plan, which they contend would damage the ability to plan lessons.

After 18 months of debate, the plan to make elementary school Mondays 6 1/2 hours long, just as other school days are, failed to pass the board Nov. 15 on a 5 to 5 vote, largely because of the $5.9 million cost.

In his proposal, Spillane has pared the cost to $3.6 million by hiring 117 instructional aides instead of teachers to handle some chores such as recess duty, physical education, or computer lab supervision to give homeroom teachers planning time.

With extended Mondays, the county's 72,000 elementary students would have the equivalent of three more weeks in the classroom -- all the more reason, Spillane said, to implement the program now instead of waiting for better economic times.

"My epitaph will say, 'The fool failed nobly,' but they'll never say, 'He never tried to do anything to improve education for youngsters,' " he said.

Monday at Elementary Schools: The longstanding practice of closing elementary schools up to 2 1/2 hours early on Mondays would end in September. About 39 art teachers and 117 teacher aides would be hired to free up time for homeroom teachers to make up for the lost Monday planning time. Cost: $3.6 million.

Salaries: Teachers and other employees would receive no cost-of-living raises, but would still receive normal step increases. Those raises, based on length of service, average about 2.6 percent, with some less experienced teachers receiving up to 5 percent and some veteran instructors at the top of the scale receiving none. Cost: $17.6 million.

Enrollment Growth: To serve an anticipated 1,710 new students, about 308 new teachers and administrators and 10 new bus drivers would be hired, and 10 new buses would be purchased. Cost: $12.2 million.

New Schools: About 40 administrators, counselors, librarians and custodians would be hired to staff two new schools opening in the fall, an elementary school north of Fair Oaks and an intermediate school in Centreville. Teachers would transfer from other schools. Cost: $2 million.

Employee Benefits: Health benefits and worker's compensation costs are expected to increase significantly. Cost: $3 million.

Utilities: Heating fuel and electricity costs are expected to rise 7.4 percent next year. Cost: $1.8 million.

Middle Schools: Three intermediate schools with seventh- and eighth-graders would be converted to middle schools by adding sixth-graders, requiring the hiring of nearly 12 employees. Cost: $473,000. SPENDING REDUCTIONS

Administrators: Sixty central office administrator positions (3 percent of non-school staffing) would be eliminated. Savings: $1.8 million.

Capital Spending: The allocation for capital expenses to school buildings would be reduced by about 27 percent. Savings: $1.5 million.

Printing: Costs would be cut 10 percent. Savings: $200,000.

Special Project Teachers: The positions of about 11 floating teachers used to help out with special programs such as English as a second language would be eliminated. Savings: $500,000.

Replacement Vehicles: The budget for administrative cars and maintenance trucks would be cut in half. Savings: $250,000.

Assistant Principals: Four positions in low-enrollment intermediate schools would be eliminated. Savings: $200,000.

Inflation: Aside from utilities, inflationary increases were not included for any area, meaning current budget must absorb higher costs.

SOURCE: Superintendent's Proposed Fiscal 1992 Budget.