More than 40 countries including Germany, Britain and New Zealand have asked the UN body that sets aviation standards to help make single-pilot flights a reality as early as 2027.

The proposed change would lowers costs and ease staff shortages but placing full responsibility on one person has raised serious objections from Australian pilots.

The Australian and International Pilots Association is warning against single-pilot flights, arguing they compromise safety.

Australian and International Pilots Association Vice President and Qantas First Officer Mark Hofmeyer said the presence of two pilots was integral to safety on board a flight.

"Airplanes have got redundancy built in all over. They have two engines, multiple electric and hydraulic systems, multiple autopilots. Having two pilots is part of that redundancy."

Redundancy in engineering refers to the intentional duplication of critical components or functions of a system with the goal of increasing reliability of the system.

Single pilot flights are not used in Australia, with a minimum of two pilots on board every domestic public transport flight.

Mr Hofmeyer cited Qantas' recent unexpected diversions into Athens and Azerbaijan due to medical and technical emergencies respectively, as examples of pilot decision making being crucial to a safe landing.

"It is the pilots that make the decisions where to go, the safest way to get there, and what to do. The automatics help fly the aeroplane, but it's not making the decisions," he said.

"And at the end of the day consequential decisions made correctly is what saves lives."

In November 2010 the engine of a Qantas A380 plane exploded during a flight from London to Sydney via Singapore.

The heroic actions of the five pilots on board resulted in the aircraft making a successful emergency landing in Singapore with no injuries to the passengers or crew.

Legendary Qantas captain Kevin Sullivan narrowly averted a horrific air disaster in 2008 when a fault in the plane's automation caused it to suddenly nosedive.

He joined the chorus of those warning against single pilot flights on Thursday.

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Concerns have also been raised that single-pilot flying would limit training and knowledge-transfer opportunities for junior officers and negatively impact pilot fatigue and mental health.

"How will junior pilots get exposed to the experience of senior crew members if they never get to sit next to them?," Mr Hofmeyer said.

"The notion that you could have a pilot with a medical episode, what's the plan for that situation? Or even something as simple as going to the toilet."

Qantas CEO Alan Joyce has flagged that Qantas will not be pushing to adopt single pilot flights.

Qantas was recently named the world's safest airline in the annual AirlineRatings.com safety rankings.

"As a society we've got a very long way to go before we would entrust our lives to one pilot and a computer," Mr Hofmeyer said.

"I know I wouldn't put my family on an aircraft that only had one pilot on it."