Aviation workers' union E tū says it's working to secure assurances about the safety of up to 10 volunteer cabin crew and any ground crew operating the Air New Zealand rescue flight from Wuhan.

E tū's head of aviation, Savage, says so far around 40 crew members have volunteered for the flight that will collect New Zealanders in Wuhan and return them home.

A Boeing 777-200 aircraft will be used for the rescue mission via Hong Kong, understood to be on Sunday or Monday, he said.

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The operating crew will fly to Hong Kong the day before so they can rest before the long flight to Wuhan and on to Auckland.

It is possible an aircraft engineer and aircraft loaders may also travel to Wuhan to ensure a successful turn-around.

Savage says a priority for the crew is ensuring everything is done to keep them safe.

"There's no shortage of volunteers, but they are asking questions about the safety protocols for the flight and they won't be flying until they're satisfied about that," says Savage.

"Crew need to know that they're safe, what their risk of infection is as well as the risk of passing something on when they get back. That's the biggest concern they have, that they could pick it up and not know it and pass it on to colleagues or friends and family.

"We may sign a special agreement for the flight to clarify what to expect and what the conditions are."

Savage says that includes covering issues such as equipment and protective clothing, quarantine and containment protocols if anyone gets sick, as well as issues related to insurance and members' sick leave if they do get sick or are quarantined.

Delegates and health and safety reps continue to be proactive in seeking the latest information from Air New Zealand on the situation, especially as other airlines suspend flights to China.

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"As the virus continues to spread, there are anxieties among airport workers. We're hearing from ground crew members at Menzies Aviation who are wary of touching baggage from China in case it puts them at risk, so there's misinformation out there about the dangers."

He said good information was the best defence against fear and anxiety.

"Airlines like Air New Zealand and Virgin Australia have so far been forthcoming with information and we expect that will continue."

It is likely the flight will return to New Zealand directly, a journey of about 13 hours.

Air New Zealand this morning announced it would scale back flying from Auckland to Shanghai between February 18 to March 31 in response to a drop in demand.

Dozens of other airlines have cut or scaled back services to China. About 20 per cent of domestic flights have also been cut in the country where close to 8000 cases of coronavirus have been reported leading to 170 deaths.