Eastern Airlines pilots launched an advertising campaign to reassure the public they will not allow any unsafe plane to leave the ground. The ads, sponsored by Eastern's Air Line Pilots Assn., were carried in Miami newspapers and on radio stations in Atlanta, New York, Washington and Boston. Miami is Eastern's base and its largest hub, and the other cities are among the carrier's major markets. The campaign was launched as the Federal Aviation Administration considers tighter rules on when airlines may postpone maintenance. Ron Cole, a spokesman for Eastern's pilots, said the pilots have instituted a "maximum safety campaign," which encourages pilots to pay extra attention to safety on their flights. The union would not disclose how much the ad campaign cost.