Air New Zealand is investigating after a series of inappropriate images of uniformed staff members were posted online.

An employment lawyer says the images could bring the airline into "disrepute", and may amount to serious misconduct.

The photos show a pilot posing with a blow-up doll inside an aircraft. It is understood the images were shared to Facebook and Instagram.

SUPPLIED Images posted to social media show Air New Zealand staff behaving inappropriately.

Another video, which appears to have been posted to Snapchat, shows a flight attendant moving through the cabin, spitting water.

The video is captioned: "Wish I could spit on passengers like this".

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An Air New Zealand spokeswoman said the airline was "shocked and appalled" by the images.

"We expect the highest standards of behaviour and respect from all our staff," she said.

The spokeswoman said the images had been brought to the airline's attention in the past 48 hours and an investigation commenced immediately.

"We believe the video was produced about four years ago and the photos were taken more than a year ago," she said.

"One of the staff members concerned no longer works for Air New Zealand and the other two have been removed from duties pending the outcome of our investigation.

"It goes without saying that this is a situation we are treating with extreme seriousness - and our obvious concern is that the behaviour displayed is a clear breach of not just our code of conduct but basic decency."

When asked for his assessment of the situation, employment lawyer Fraser Wood said any action that brought an employer into disrepute may be grounds for serious misconduct, which would justify dismissal.

"Particularly in a situation where they are in full uniform, it would be difficult to argue that they would not bring the company into disrepute by virtue of those photographs."

The context the images were taken in would be an important factor in Air New Zealand's investigation, as well as how widely they were dispersed, he said.

Wood said employment cases involving social media were becoming relatively common, as people were "very casual" in terms of what they posted.

"Don't post anything you don't want your parents or employers to see," he warned.