FOR HIS THIRD secretary of transportation, President Reagan has selected James Burnley IV, who comes to the nomination with endorsements from both previous secretaries: Elizabeth Dole and Drew Lewis. Mr. Burnley, who has served as No. 2 official in the department since 1983, has been an aggressive advocate on Capitol Hill of the administration's air safety and other transportation policies -- which at times has led to clashes with key congressional committee members. But this vigorous style has been neither obstructionist nor unreasonable. Mr. Burnley has solid experience in, and knowledge of, what has come to be a vast range of activities handled by the department. Colleagues as well as those with whom he has sparred consider him a professional who is thoroughly familiar with the DOT's day-to-day operations and who has participated directly in its policy making.

Foremost among these responsibilities now is aviation -- policies that have come under growing criticism from the public as well as Congress. Air safety, service, fares and regulation are all hot topics in Congress -- where a mixed bag of legislation keeps growing. Though Mr. Burnley is not seen as one who would overturn past administration positions, the structure and status of the Federal Aviation Administration could stand a critical assessment from an administrator who knows its workings.

The department has not exactly broken records rebuilding the air-traffic-controller force, but recent moves have quickened the pace. Along with this, supporters of Mr. Burnley say he could be expected to push effectively for increased airport capacity and technological improvements. If significant improvements are to be made between now and the end of the Reagan administration, Mr. Burnley would appear to be a logical choice to make things move.