Montgomery County Executive Charles W. Gilchrist, saying local officials have failed in their decade-long effort to cope with the affluent county's rapid growth, launched a campaign yesterday to wrest control over development from his political rivals on the County Council and Planning Board.

"Our planning process is broken and needs fixing," Gilchrist said, as he announced the appointment of 17 prominent builders, civic leaders, business executives and lawyers to a legislative task force. The panel is charged with rewriting state and county law governing the local planning board, a state-created body that controls the use of virtually all land in Montgomery.

In appointing the mostly Democratic task force, Gilchrist all but directed it to draft legislation giving the county executive authority to appoint planning board members, control the county's "master plan" blueprint for growth and veto even the smallest zoning decision made by the County Council.

Gilchrist hopes to restore to the office of county executive the broad power once held by the county's first executive, Republican James P. Gleason, before a Democratic-controlled County Council in the early 1970s stripped him of those prerogatives.

The timing of Gilchrist's plan, which was received coolly yesterday by County Council members and Planning Board Chairman Norman L. Christeller, was nearly as important as its substance, several officials said.

The attempt to increase the executive's power over land planning comes in the thick of demographic changes that have left hundreds of Montgomery parents demanding new schools for their children and thousands of commuters clamoring for wider roads and a more efficient transportation network.

In addition, by starting this campaign more than a year before leaving politics to study for the Episcopal priesthood, Gilchrist enjoys the luxury of appearing above politics -- an advantage in the lively public debate sparked months ago by Montgomery's overcrowded schools and congested highways.

"Traffic on the Beltway is bumper-to-bumper and nobody cares -- that's the mess Montgomery County's in," said Martin Alloy, a Silver Spring developer who was named to the task force.

Alloy, whose Stanley Martin Communities firm has constructed 5,000 houses in the county and is currently building 300 more, said Montgomery has made the mistake of deciding land use "by committee," with often-competing viewpoints from Gilchrist's staff, the planning board, County Council and officials from Maryland state government.

The splintered agencies trying to chart the county's future have spawned dozens of wildly varying public and political pressures, Alloy went on to say.

In an area just east of Rockville, "there's no development because the schools are too crowded," Alloy said. "But they closed Northwood High, and neighboring Kennedy is crowded. People don't want to wait at two red lights on Rockville Pike, but if you make the Pike convenient, who'll ride Metro?

"We want to keep Montgomery County green, but we also want wider roads," Alloy added. "If this county doesn't solve these problems, you're going to see a lot of companies pack up and leave."

Alloy and several others in local development echoed Gilchrist's call for more executive control over planning, pointing to many other jurisdictions, including Prince George's County, where the government's executive holds appointment power over the planning board.

Planning managed by an elected executive serves voters and taxpayers better than Montgomery's tradition of a planning board chairman appointed by the County Council, Gilchrist and his supporters said.

"We have a too-strong planning board," Gilchrist said. "They are not elected. They have enormous power. They are not accountable to the public."

But William E. Hanna Jr., vice president of the County Council, disagreed, saying the fact that comparable governments act differently "is no argument for change at all."

"Planning should be done in the open" and not in the "secrecy of an executive agency," Hanna added.

Gilchrist's task force has until September to recommend changes to existing county and state law governing the planning board. That would give the executive enough time to prepare legislation for the 1986 General Assembly. It will be asked to approve amendments to the 1927 Regional District Act, which established Montgomery's planning agency