The Air Line Pilots Association (ALPA) and other US pilot groups have come out swinging against proposed legislation that calls for the Federal Aviation Administration to study single-piloted cargo aircraft.

"You don't make flying safer by removing pilots from the cockpit," ALPA president Tim Canoll says during the union's annual Air Safety Forum on 1 August. "The flying public would simply not accept the lower level safety that would result." ALPA and several other unions likewise issued a joint media release on 1 August saying they wanted "Congress to know how reckless passage of a bill with this provision would be".

ALPA's partners in the effort include the International Brotherhood of Teamsters, the Allied Pilots Association, the International Brotherhood of Teamsters, the Southwest Airlines Pilots Association and others.

The House version of the FAA's reauthorisation bill would order the FAA and other federal agencies to "establish a research and development program in support of single-piloted cargo aircraft assisted with remote piloting and computer piloting".

The measure, which is not included in a Senate version of the FAA bill, comes amid a widespread shortage of pilots and as autonomous systems for other modes of transportation grow increasingly sophisticated and commonplace.

Safety experts have long said some aviation accidents, such as the 2009 crash into the Atlantic Ocean of Air France flight 447, would not had occurred had automated flight systems been in charge.

ALPA, however, insists pilots can help avert disasters, citing, for instance, the ditching of US Airways flight 1549 into the Hudson River in 2009.

"Despite these clear examples to how two pilots in the cockpit makes such a tremendous safety difference, some are trying to remove them," Canoll says.

But momentum for pilot-less commercial aircraft has increased.

Last year Boeing said it was studying autonomous technology for a passenger aircraft, a project that included plans to flight-test such technology.

Also last year, bank UBS released a report saying pilot-less passenger or cargo aircraft could fly by 2025. That report notes that sophisticated cockpit systems have already assumed many tasks formerly performed by pilots, leaving pilots primarily tasked with "managing and overseeing".

Besides reducing airlines' pilot costs, pilot-less systems can operate aircraft more efficiently and provide insurance savings and other benefits, saving the airline industry an estimated $35 billion in the next two decades, UBS says.

Though technology exists, UBS notes that consumers have not yet fully embraced the idea of a cockpit void of human oversight.

ALPA's Canoll makes the same point, saying the majority of Americans "strongly oppose" the idea of one-pilot or pilot-less passenger aircraft.