COLLEGE PARK -- Small airports are facing an increasingly tough battle as the neighbors of airfields that cater to light planes become more concerned about safety and as economic pressures mount to develop their airfields.

The number of general-aviation airports open to the public in Maryland has dropped from 44 in 1978 to 39 this year, according to Albert Selby, a spokesman for the State Aviation Administration.

The land at two of the closed airports -- the Aberdeen Airpark in Aberdeen and the Park Hall Airport in St. Mary's County -- has been converted to housing, Selby said.

"The problem is that pressures to develop land are so great that the small airports are being sold off," said Patricia Weil, a spokeswoman for the Aircraft Owners and Pilots Association.

She said most of the airports were once in rural areas that have become developed over the years. As land around the airports is developed, the public's concerns about noise and safety increase.

Among the hostile signs that airport advocates see around them is a plan to run a road through a grove of trees near the 40-acre College Park Airport, whose boosters claim is the oldest continuously operated airport in the United States.

The road would pass within 18 feet of the footings of hangars once used by the Wright brothers when they trained Signal Corps pilots from 1909 to 1912.

Plans for new general-aviation airports in Charles and Calvert counties were recently killed, both by local opposition.

In Anne Arundel County, the Lee Airport and its surrounding neighbors are locked in a dispute over how much of the airport's 79 acres should be used as an airfield.

The Annapolis Flying Service, which leases the property near Annapolis from a private owner, has been using about 22 acres.

County records show approval for only 16 acres.

But advocates of small airports say they provide a necessary service and note that general aviation has become safer.

"We provide a needed service and a lot of people don't realize that," said William Broach, manager of the Forest Hill Airport near Churchville.

According to the Aircraft Owners and Pilots Association, the number of hours general-aviation planes spend in the air has remained stable at about 30 million a year. Fatalities have declined from 658 in 1976 to 466 in 1986.

At the Baltimore Airpark in White Marsh, airport manager Christopher Kreeger said complaints about airport noise are routine, particularly on summer weekends when the owners of many of the airport's 45 planes take to the skies.

"Neighbors don't think about it before they move in," he said.

To appease the neighbors, he added, the airport has set a requirement that planes taking off make no left turn over the residential areas until they are at least 700 feet above the ground.

Policing airborne traffic is often impossible, Kreeger said.

A pilot himself, he takes an aviator's perspective.

"I've gotten so that I love plane noise," he said. "I love hearing planes and looking up in the sky and seeing planes."

Ken Medley, a regional representative for an eight-state region that includes Maryland for the Aircraft Owners and Pilots Association, is critical of county regulatory officials statewide who allow housing to be built near general-aviation airports.

"The problem is that you go out in the country and you build an airport and things are fine for a while," he said. "But then you build houses right next to it. If they wouldn't allow it to be built there, it wouldn't be built there."