Astronaut Mike Mullane talks about work safety at Whangarei refinery

For former US astronaut Mike Mullane, taking a giant leap for mankind these days means helping make sure hazardous workplaces are safe.

Retired USAF Colonel Mullane "rode" several Apollo missions and other space shuttles during his stellar career.

He has written and talked widely about the the fear, pressure, triumph, challenge, reward and perceived heroism of being an astronaut.

But in 1986 he went through the anguish of watching the Challenger shuttle explode on take-off, causing the death of seven friends and colleagues.

Since then - at times annoying NASA - he has spoken out about the need for employees to act on any doubts they feel or deviations they see in safety procedures, no matter how slight.

Mullane was in Whangarei on Monday talking to Refining NZ staff about the need for workers in every workplace, particularly hazardous ones, to feel confident and authorised to put up a hand and say "stop work".

Tiny discrepancies in operational practices often become routine and no longer noticed or questioned, which Mullane termed "normalised deviation".

Refining NZ already has a site-wide stop work order that authorises any worker to do just that.

Chief executive Sjoerd Post said the system had been tried and worked.

"It gives every worker the courage to intervene, backed up by the authority to do so," he said.

The refinery invited Mullane to visit New Zealand, in conjunction with the Business Forum, to talk about workplace culture where workers at any level viewed safety as more than just an imposed checklist that needed ticking off.

"Mike [Mullane] is here because we need a fresh conversation around safety," Post said.

There was a time Mullane would jump into a US Air Force fighter jet and, later in his career, into a space shuttle knowing there were "multiple failure pathways".

Those in charge would always explain there was a chance something could go wrong but instead of thinking it might happen, everyone thought "it hasn't happened yet; and it probably never will."

Today Mullane would call that attitude normalised deviation.

Failure is not always systemic or the result of a built-in flaw: humans are often under pressure at work because of something else in their life, and that is the nature of life, he said.

As well as talking about a new culture required in hazardous workplaces, Mullane is a motivational speaker, which 35 Whangarei secondary school students will learn on Tuesday.

He will address representative senior students from Whangarei schools about his life and times as an astronaut, a subject he has written frankly about in his biography, Riding Rockets.

"I was a pretty ordinary kid," he said.

"My message, the four points I tell young people is dream big, take care good care of the only body you're ever going to have, make the most you can of getting an education, and don't be afraid of aiming high."