US pilots called for enhanced pilot training on Boeing 737 MAX before the aircraft is returned to service

US pilots called Wednesday for enhanced pilot training on the Boeing 737 MAX before the aircraft is returned to service after being grounded worldwide following two deadly crashes.

The pilots -- including Chesley "Sully" Sullenberger III, 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.

Daniel Carey, president of the Allied Pilots Association, told a congressional panel 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 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 a House committee.

Sully demanded simulator training for MAX pilots, saying the computer-based program used previously was not sufficient.

Pilots must be subjected to what can go wrong during a simulation and "need to develop a muscle memory of the reactions so that it'll be immediately accessible to them" in an actual crisis, Sullenberger said.

The hearing, the third in Congress since the aircraft was grounded in mid-March, comes as Boeing continues its work with the US Federal Aviation Administration and other regulators in an effort to the MAX recertified and back in the skies in 2019.

Leading US carriers have pushed back their schedules for returning the planes to service as the timeframe for FAA approval has been extended.

A key question is whether pilots should be required to undertake flight simulator training before the planes are brought back to service. Such a requirement would involve thousands of pilots and likely extend the time needed for flights to resume.

Carey said one possibility was a computer-based training stage initially, with simulator training for all MAX pilots within 10 months.