Since the first of this year, the National Transportation Safety Board has suffered a major exodus of its most experienced air safety experts. Some took promotions, while others transferred to related jobs at the Federal Aviation Administration or the National Aeronautics and Space Administration.

But many of those leaving have so much experience that some board watchers fear that the agency's reputation for quality technical work will be severely damaged.

Several reasons are cited for the departures, including the fact that the board is a small agency with limited promotion possibilities and that its work schedule disrupts peoples' lives. Everybody pulls duty on the board's "go teams," whose members must be available 24 hours a day to investigate a crash.

Board sources also say that morale and communication problems between agency managers and aviation staff have also contributed to the exodus. Safety Board Chairman Jim Burnett and Managing Director J. Peter Kissinger are both accused of using managerial styles that encourage job-seeking.

One board expert said, "I thought the way they were treating the aviation people was unnecessary and too personal. I don't believe in cutting people out of the line. I would have done it differently."

Burnett has devoted great time and effort to increasing the board's impact in highway and railroad matters, which receive less media attention and where the board is less well known. A result has been a feeling by some that aviation is being given less emphasis.

Burnett said yesterday, "What we have done in achieving the impact we are having on highway and rail safety we have done without having diverted from aviation."

"Some people think I get involved in how to allocate resources too much," Burnett said. "I think it's a good thing . . . . To some extent I think the board investigated accidents in the past just to provide data for people such as litigators." He said he is proud of pushing investigations into areas other than crashes, and cited a board study underway on recent near-collisions on runways as an example "of good work in picking up on the trend from incidents, before we have accidents."

Aviation safety is receiving more attention than it has in years because of unprecedented numbers of deaths worldwide in civil crashes, more than 1,444 this year, including a crash that killed 14 in Virginia. "We have sent out more investigating teams in the past four months than we usually do in a year," Kissinger said.

Those who have left or will leave shortly include William R. Hendricks, longtime chief of aviation accident investigations, who becomes FAA deputy associate administrator for aviation standards.

Others who joined the FAA in recent months include Gale Braden, an expert in crash survivability; Dave Thomas, one of the board's investigators in charge, and Robert A. Watson, an engineer.

Tom McCarthy, another board senior investigator in charge, has left for NASA, along with Carol A. Roberts, an electrical engineer who is the nation's -- if not the world's -- leading expert in retrieving data from the so-called "black boxes," or flight data recorders.

John Ferguson, who retired once from Trans World Airlines to become the board's expert on pilot behavior and operations, has now retired from the agency.

Burnett said, "While we are certainly losing some people who have contributed to the prestige of the board, we are also promoting people who have contributed to the prestige of the board."

STOP THE PRESSES. . . Since the Reagan administration took office, the Transportation Department's Public Affairs Office has specialized in late-afternoon press releases, some of which contain news.

Reporters who regularly cover the department have attributed that to normal bureaucratic snafus, because the agency has a long list of people who must clear a press release before it can go out, especially if it quotes Transportation Secretary Elizabeth Hanford Dole.

Suspicions of calculated intent surfaced last week, however, when the administration's long-awaited trucking deregulation bill was released at 6 p.m. One way to assure that a controversial issue will not get full airing in the next day's papers is to announce a major development late in the day.

Washington Post reporter Eleanor Randolph wrote in June that many Washington journalists think there is an intentional effort by this administration to reduce reporters' access to information. Was this incident part of an overall scheme?

"Not at all," said Jennifer Hillings, assistant secretary for public affairs.

Department sources said the real reason for the late news was because Dole got clearance for the bill early in the afternoon and wanted it pushed to Capitol Hill that day, before the White House or the Office of Management and Budget changed their minds.