A National Transportation Safety Board proposal to ban news aircraft near disaster scenes has raised the ire of several San Francisco broadcasters. The agency has urged the Federal Aviation Administration to adopt stringent guidelines limiting such coverage, expressing concerns that planes used by news crews could interfere with emergency aircraft in disaster situations. The board cited two Bay Area tank truck accidents (in 1981 and 1985), suggesting news helicopters hovering over the accident sites helped spread toxic fumes. The broadcasters feel the ban would be a form of censorship and say that existing restrictions against the media, including the cancellation of pilot licenses, are strong enough. "I'm against any rule that ends up preventing the dissemination of information," said Herb Dudnick, KRON-TV's news director.