Fairfax County Sheriff James D. Swinson has refused to back down from his request for a 50 per cent increase in personal to staff the new jail, which is scheduled to open in September.

"No, I don't know of any way to cut down on the number of new personnel, other than to completely revamp the jail," Swinson said in an appearance Tuesday before the Board of Supervisors to justify the increase, which will cost about $700,000.

"I am really being conservative in my estimate," Swinson said, "I think I will have to cme back and ask for some more people next year."

"I am appaled," Supervisor Audrey Moore (D-Annandale) told Swinson about his request for 45 more guards and other personnel, an increase of 51 per cent over the last fiscal year.

"I feel a little a bit taken." Supervisor Martha V. Penino (D-Centreville) said, cl aiming that the Board was given no inkling that such an increase would be needed when it approved construction of the $5.4 million jail two years ago.

But other supervisors, with varying degrees of enthusiasm, defended Swinson and the staffing decrease.

"The buck stops here," Supervisor Alan H. Magazine (D-Mason) said. "No question were raised (by board members) two years ago. We were in such a hurry to approve a new jail, and with good reason."

Supervisor John P. Shacochis (R-Dranesville) noted that Swinson's proposed increase is actually lower than the state's. The department of corrections proposed 62 new positions, against Swinson's 45.

Deputy County Executive James P. McDonald, who is in charge of financial affairs, told the supervisors when he was questioned that "we are satisfied that the staff that is being recommended (by Swinson) is the base he must have."

Asked by Supervisor James D. Scott (D-Providence) "What did we do wrong?" McDonald said the information gap on staffing needs happened because the timetable for capital costs (like the new jail) was not synchronized with forecasts for operating costs last year. The forecast for the increase in new personnel that would be needed, he said, "got caught in the middle and fell in a crack."

The new jail, called the adult detention facility, is located adjacent cent to the Massey Building government center in Fairfax City and to the side of the proposed new courthouse, which also has been approved in a country hood referendum.

The jail, which will be able to hold 188 men in medium and maximum security cells and 12 women in a separate unit, will replace the present, badly overcrowded jail at the courthouse.

In other developments at Tuesday's meeting, the Supervisor gave a luke-warm reaction to a study looking at alternative air corridors aimed at reducing the noise impact from planes taking off from and landing at National Airport.

According to the study, prepared by the Fairfax-based Mitre Corp. for the Metropolitan Washington Council of Governments (COG), the alternatives - which would widen the planes' pathways coming and going - would reduce the noise problem of 27,000 county residents, but would increase the problem for 20,0000 other residents, most of them in the Franconia and Springfield area.

Paul Shernfels, group leader for air transportation systems at Mitre, who gave a presentation to the Supervisor, said, "Somewhere in between the two extremes (present corridors and the alternatives) may be a net gain."

The alternative will be aired at public hearing to be held in the metropolitan area the week of May 16. The time and place of those hearings will be announced by COG when it complete arrangements.

While COG will make its recommendations after the hearings, the ultimate decision on the air corridors will be made by the Federal Aviation Administration.

The Supervisors declined to take any action on Mitre's alternatives, which would bring more noise to about 4,000 residents in the McLean Langley area, 57,000 people in the southern part of the country and 20,000 in the central area, while reducing noise new affecting about 25,000 people many of them in the Mount Vernon area.

Before they act, the Supervisors said they want country staff to study the technical assumptions of the Mitre study.

John H. Thillman, the country's air transportation planner, said some of the noise reduction would take place in industrial areas, and therefore would have less benefit than a reduction in residential areas.