An Air NZ crew who will be on board a Government-chartered flight bringing home Kiwis stranded in China, have landed in Hong Kong.

Etu Union's director of aviation Savage told the Herald the 10-strong crew flew out on a Cathay Pacific flight about 3pm yesterday so they had time to rest before their 18 to 19-hour return flight from Wuhan.

"Because of duty time limitations they actually flew the crew out yesterday ... they have a 16-hour limit and if they go over that they have to negotiate the special circumstances which they've done in this circumstance."

He said none of the crew had ever landed in Wuhan before, so pilots had been going over the flight path as they prepared for the journey.

Wuhan was about 600km inland from Shanghai, he said.

"Prior to the departure, the four pilots for the Wuhan flight practised in the Air NZ simulators approaches and departures for Wuhan and they've taken with them an engineer and a loader, another Etu member, to make sure they don't have any problems or to troubleshoot any problems on the ground in Wuhan."

It would take about 90 minutes to get from Hong Kong to Wuhan.

"The idea is they don't even leave Hong Kong until they're pretty sure they're going to be able to get in and out without any problems."

There were two considerations for the crew, health and safety and "that includes whether or not they would be stood down in quarantine when they returned from duty. The other that became apparent late on Friday night, the flight time and the time on the ground from Hong Kong to Auckland would be somewhere between 18 and 19 hours."

Normally a return flight would see them spending about an hour on the tarmac. However, this flight, given the special precautions, would be around two hours.

"When you get up to 18-19 hours that's ultra-long-haul flying. So for both pilots and cabin crew, that meant signing a special service agreement to allow for crew and pilots to fly in excess of what would normally be agreed."

The agreements are the same as those used for crews flying to Chicago or New York.

"Obviously it's very fatiguing for a crew to be spending that long working ... but they will have rest breaks on the plane."

The crew that had flown over were all "very experienced", he said.

"They went for the right reasons. They go because they could see that there are fellow New Zealanders who need help."

The flight service manager on the plane was not only experienced in his job, but was also a volunteer firefighter, medic and union delegate.

On Friday afternoon, there was a 90-minute meeting led by Dr Sally Roberts from the Ministry of Health chatting with union delegates, Air NZ managers and crew about the risks, operational procedures and how meal preparation would be handled to ensure no risk of infection from passengers.

That would see all Air NZ crew wearing surgical gloves and masks when in with the passengers, while the business class section would be cordoned off for crew and Ministry staff and doctors to rest.

The biggest risk for crew would be not taking their gloves on or off properly, he said.

"Our union delegates were left feeling very reassured after talking to her that, number one, there would be a Ministry of Health medical team on board the plane, there would be screening of passengers before they got on the plane, and anyone exhibiting symptoms like coughs and fever would likely not be allowed on the plane."

However, a cough or fever could just mean they had a cold and not necessarily the virus as it was currently winter in China.

"If they picked up the virus just before they got on the plane and they still weren't exhibiting symptoms, then due to the nature of coronavirus, as we understand it, they likely would not be infectious if they were not yet exhibiting the symptoms."

As a precaution, passengers would be spread out around the plane to ensure enough space between them.

Coronavirus was spread through coughing and sneezing - saliva. It had heavy droplets as opposed to other viruses, so it didn't spread as far - about a metre - and then drops to a surface.

"So the risks are being close to someone, or them coughing on a surface and you touching it."

He said coronavirus was just a bad flu from which people would recover. However, if a person's health was already compromised, it could turn fatal.

"It's not as if you get it and you're a goner. You can survive. People need to remember that it is a new form of flu virus, so keep it in perspective, and we will be encouraging crew to do that."

Once everyone was on the plane it would all be about looking after the passengers, he said.

"Some of them have been stuck in Wuhan a long time and have other medical conditions pre-existing that they need looking after ... the medical team and an Air NZ doctor will be on board."

If a passenger did start exhibiting symptoms there would be an area set aside on the plane for them to be moved further away from others to eliminate any risk of transmission.

It was unclear how many passengers they would be picking up, but he said it would be at least 100. The 777-200 plane had just over 300 seat capacity.

The only other issue for the Air NZ crew was whether they would be quarantined on their return.

He said that decision wouldn't be made until they're on their way home and would be made at the advice of the Ministry of Health.

However, all going well, the crew would have their normal three-day duty stand-down, followed by an extra day, which should be sufficient time for any symptoms to present.

As for the aircraft that is being used, Savage said Air NZ had special "deep cleaning methods" which it used on planes after a passenger had been ill.

"The entire interior of the plane will be subject to comprehensive cleaning. It's no different from standard cleaning but it will involve the whole plane."

The plane itself had a very sophisticated air circulation and filtering systems which would be checked before and after, and likely replaced, before the plane is used again.

He said Etu's safety concerns also included other crew, including catering and cleaning staff.

The Ministry of Health is holding a press conference in Wellington at 4pm today, when an update will be issued.

Meanwhile, Air New Zealand is asking customers heading off on international trips to allow for extra time for check-in, as many countries have introduced new travel restrictions.

Air NZ's Doug Grant said with additional checks required for many of the airline's destinations, airport check-in areas were busy.

"Our teams are working hard to get travellers where they need to go. This is a busy time and we thank customers for their patience and understanding."

THE RECOVERY MISSION

• A 10-strong Air NZ crew has already landed in Hong Kong,
• The return flight with Kiwis should be leaving soon,
• An Air NZ doctor and Ministry of Health staff to also accompany passengers home,
• Crew and Ministry staff to rest in cordoned off business class area of plane,
• Flight will only depart Hong Kong once assured they can land in Wuhan,
• Air NZ crew to rest for four days upon arriving home,
• Whole interior of plane subject to extensive "deep clean" once back in NZ, filtering system likely replaced,
• Ministry of Health to issue next update at 4pm today,
• Air NZ now asking international passengers to allow extra time for check-in.