Aviation industry members on Tuesday again urged lawmakers for newer air traffic control technology and more hiring of air traffic controllers as airlines continue to complain about longtime shortfalls, while air travel demand has boomed.

Their testimony was delivered to a House committee hearing about a month after an American Airlines regional jet and an Army Black Hawk helicopter collided near Ronald Reagan Washington National Airport, killing all 67 people on board the two aircraft in the deadliest U.S. airline crash since 2001.

Transportation Secretary Sean Duffy said last week that the Trump administration is taking steps to increase air traffic controller staffing, raising starting salaries by 30% for staff who go through the Federal Aviation Administration’s academy.

Air traffic controller staffing is down about 9% from 2012, while air travel demand has hit new records, according to testimony from Nick Daniels, president of the National Air Traffic Controllers Association.

Duffy’s comments come as President Donald Trump has tasked his billionaire advisor Elon Musk with cost-cutting throughout the federal government. But Musk’s involvement has raised concerns about conflicts of interest from Democratic lawmakers, especially since the FAA is one of the regulators of Musk’s company SpaceX.

The cost cuts have layoffs of included about 300 FAA employees. The DOT said it didn’t include air traffic controllers.

“This demoralizes the entire workforce and distracts from the agency’s efforts to modernize and improve the aviation system — as well as taking away from the primary mission of the FAA to ensure the safety and effectiveness of the U.S. aviation system and ultimately, the safety of the American flying public,” David Spero, president of the Professional Aviation Safety Specialists, said in written testimony.

He said “blanket changes, indiscriminate dismissals or other arbitrary edicts will not help this country maintain the safest air traffic control system.”

For his part, Nick Calio, head of Airlines for America, which represents major U.S. airlines including United Airlines, American Airlines, Southwest Airlines and others, recommended relying on Musk’s so-called Department of Government Efficiency or “procurement experts from the private sector to revise the procurement standards, policies, practices and procedures of the FAA to reduce any impediments to the acquisition of commercial products and commercial services, or other sources, as required.”