NEW YORK: US pilots, including Chesley "Sully" Sullenberger III, called Wednesday for enhanced training on the Boeing 737 MAX before the aircraft is returned to service following two deadly crashes.

Sullenberger, who famously landed a damaged plane on the Hudson River in New York in 2009, pushed back against the aviation giant's assurances that pilots will only need to review the 737 MAX modifications in a computer program.

"Pilots must develop the muscle memory to be able to quickly and effectively respond to a sudden emergency," Sullenberger told a House of Representatives subcommittee.

"Reading about it on an iPad is not even close to sufficient; pilots must experience it physically, firsthand."

Daniel Carey, president of the Allied Pilots Association, said he was encouraged by changes Boeing made to a flight system seen as a factor in both the Lion Air and Ethiopian Airlines crashes that killed a total of 346 people.

But Carey, a captain with American Airlines, sharply criticized Boeing's development process of the MAX plane and said he was troubled that the training being discussed by the manufacturer would be insufficient.

"We remained concerned about whether the new training protocol, materials and method of instruction suggested by Boeing are adequate to ensure the pilots across the globe flying the MAX fleet can do so in absolute complete safety," Carey told the House panel.

What pilot training to require is among the prime questions facing Boeing as it works with the Federal Aviation Administration and other regulators in an effort to get the MAX recertified and back in the skies in 2019. The planes have been grounded globally since mid-March.