James H. Burnley IV, President Reagan's nominee to be Transportation secretary, pledged yesterday to be an aggressive traffic cop who would police the airline industry to make sure that safety is maintained.

Burnley said he would immediately seek help from Congress in maintaining funding for the air traffic control force if Congress and the White House fail to reach a budget agreement by Friday, triggering automatic across-the-board spending cuts.

With the reductions that would be required in the Federal Aviation Administration work force, "we would literally have a disaster on our hands in {the FAA's} ability to function day to day," he said.

Burnley faced an audience of generally friendly senators considering his appointment to succeed Elizabeth Hanford Dole. Dole left DOT Oct. 1 to help with her husband's campaign for the Republican nomination for the presidency.

As Dole's deputy secretary, Burnley had rankled some members of Congress, but yesterday there were no signs of hostility on either side. In fact, the only vocal opposition to his nomination came from consumer advocate Ralph Nader, who questioned Burnley's commitment to safety.

Two days after the second major air crash this year, in which 27 passengers departing from Denver on a Continental Airlines flight were killed, safety was clearly very much on everybody's mind.

"You're going to have an increase in accident rates because you're overflying the system," said Sen. Brock Adams (D-Wash.), a former Transportation secretary.

Burnley said he would support increasing the number of controllers. He also said the FAA might require some fundamental changes to keep up with a rapidly evolving industry.

Advocates of deregulation, including himself, bear a special responsibility to make sure that safety is not deregulated, Burnley said. "It just cannot be the case that we skimp on the safety side."

Members of the Senate Commerce, Science and Transportation Committee, who are expected to approve Burnley's nomination later this week, raised a variety of concerns about DOT and the transportation industry in addition to safety.

"Nearly a decade after the advent of deregulation, airline travel in this country is the pits," said its chairman, Sen. Ernest F. Hollings (D-S.C.).

"The margin of safety has declined, record numbers of air travelers have been inconvenienced, and the airlines themselves are gobbling each other up in a wave of mergers that leaves us with no clue as to where this industry is headed," he said.

Nader said that Burnley "does not believe in enforcing the safety laws under his aegis."